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Gametogenesis, encompassing both spermatogenesis and oogenesis, exclusively originates from primordial germ cells residing within the gonadal ridges, bypassing any contribution from somatic cell lineages.
Gametogenesis, encompassing both spermatogenesis and oogenesis, exclusively originates from primordial germ cells residing within the gonadal ridges, bypassing any contribution from somatic cell lineages.
False (B)
The theca externa, a peripheral layer of the ovarian follicle, is primarily characterized by its avascular nature and contribution to steroidogenesis through direct enzymatic conversion of cholesterol to estradiol.
The theca externa, a peripheral layer of the ovarian follicle, is primarily characterized by its avascular nature and contribution to steroidogenesis through direct enzymatic conversion of cholesterol to estradiol.
False (B)
Spermatogenesis, the process of sperm production, is initiated at puberty due to the pulsatile release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the adenohypophysis, acting directly on spermatogonia and Leydig cells respectively.
Spermatogenesis, the process of sperm production, is initiated at puberty due to the pulsatile release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the adenohypophysis, acting directly on spermatogonia and Leydig cells respectively.
True (A)
Cytoplasmic bridges, persistent intercellular connections during spermatogenesis, facilitate synchronous maturation and intercellular transport of meiotic products, ensuring uniform genetic recombination across the germ cell clone.
Cytoplasmic bridges, persistent intercellular connections during spermatogenesis, facilitate synchronous maturation and intercellular transport of meiotic products, ensuring uniform genetic recombination across the germ cell clone.
During spermiogenesis, the transformation of spermatids into spermatozoa, the acrosome is derived exclusively from the endoplasmic reticulum, encapsulating hydrolytic enzymes essential for ovum penetration.
During spermiogenesis, the transformation of spermatids into spermatozoa, the acrosome is derived exclusively from the endoplasmic reticulum, encapsulating hydrolytic enzymes essential for ovum penetration.
Sperm capacitation, a prerequisite for fertilization, is primarily induced within the epididymis through interactions with epididymal fluid, leading to destabilization of the plasma membrane and hyperactivation of motility.
Sperm capacitation, a prerequisite for fertilization, is primarily induced within the epididymis through interactions with epididymal fluid, leading to destabilization of the plasma membrane and hyperactivation of motility.
The acrosome reaction, triggered by direct contact with the zona pellucida, involves the exocytosis of acrosomal enzymes, including collagenase and esterases, facilitating sperm penetration through the oocyte's vestments.
The acrosome reaction, triggered by direct contact with the zona pellucida, involves the exocytosis of acrosomal enzymes, including collagenase and esterases, facilitating sperm penetration through the oocyte's vestments.
Fertilization is completed upon the fusion of sperm and oocyte plasma membranes, immediately followed by the resumption of meiosis II in the oocyte and the extrusion of the first polar body.
Fertilization is completed upon the fusion of sperm and oocyte plasma membranes, immediately followed by the resumption of meiosis II in the oocyte and the extrusion of the first polar body.
Cortical granules, localized within the oocyte cortex, release their contents into the perivitelline space upon fertilization, initiating the 'zona reaction' which involves structural modification of the zona pellucida via glycosaminoglycans cross-linking.
Cortical granules, localized within the oocyte cortex, release their contents into the perivitelline space upon fertilization, initiating the 'zona reaction' which involves structural modification of the zona pellucida via glycosaminoglycans cross-linking.
Metabolic activation of the oocyte post-fertilization is characterized by a transient decrease in intracellular calcium ion concentration, promoting DNA replication and subsequent cleavage divisions.
Metabolic activation of the oocyte post-fertilization is characterized by a transient decrease in intracellular calcium ion concentration, promoting DNA replication and subsequent cleavage divisions.
Cleavage divisions, following zygote formation, are characterized by rapid mitotic cycles without significant cytoplasmic growth, resulting in progressively smaller blastomeres and an overall increase in embryonic volume.
Cleavage divisions, following zygote formation, are characterized by rapid mitotic cycles without significant cytoplasmic growth, resulting in progressively smaller blastomeres and an overall increase in embryonic volume.
The morula, a solid ball of cells formed during early cleavage, is characterized by distinct polarity, with inner cell mass precursors localized cortically and trophoblast precursors situated centrally.
The morula, a solid ball of cells formed during early cleavage, is characterized by distinct polarity, with inner cell mass precursors localized cortically and trophoblast precursors situated centrally.
Blastocyst formation involves cavitation, a process driven by active sodium ion transport into intercellular spaces, drawing water osmotically and creating the blastocoel, while the zona pellucida remains intact.
Blastocyst formation involves cavitation, a process driven by active sodium ion transport into intercellular spaces, drawing water osmotically and creating the blastocoel, while the zona pellucida remains intact.
Implantation, the process of blastocyst embedding into the endometrium, typically commences around day 4 post-fertilization, initiated by trophoblast cells at the abembryonic pole.
Implantation, the process of blastocyst embedding into the endometrium, typically commences around day 4 post-fertilization, initiated by trophoblast cells at the abembryonic pole.
On day 8 post-fertilization, the trophoblast differentiates into the cytotrophoblast, a multinucleated syncytium responsible for invading the endometrium, and the syncytiotrophoblast, a mitotically active layer providing cellular precursors.
On day 8 post-fertilization, the trophoblast differentiates into the cytotrophoblast, a multinucleated syncytium responsible for invading the endometrium, and the syncytiotrophoblast, a mitotically active layer providing cellular precursors.
The hypoblast layer, derived from the inner cell mass, is composed of columnar epithelial cells and contributes directly to the formation of the embryonic epiblast and definitive germ layers of the embryo proper.
The hypoblast layer, derived from the inner cell mass, is composed of columnar epithelial cells and contributes directly to the formation of the embryonic epiblast and definitive germ layers of the embryo proper.
Lacunae, fluid-filled spaces within the syncytiotrophoblast, initially contain maternal blood and glandular secretions, establishing a primitive uteroplacental circulation around day 9 post-fertilization.
Lacunae, fluid-filled spaces within the syncytiotrophoblast, initially contain maternal blood and glandular secretions, establishing a primitive uteroplacental circulation around day 9 post-fertilization.
The exocoelomic membrane, also known as Heuser's membrane, is derived from the cytotrophoblast and lines the exocoelomic cavity, which subsequently develops into the definitive amniotic cavity.
The exocoelomic membrane, also known as Heuser's membrane, is derived from the cytotrophoblast and lines the exocoelomic cavity, which subsequently develops into the definitive amniotic cavity.
Extraembryonic mesoderm, originating from the cytotrophoblast, fills the space between the trophoblast and Heuser's membrane, and subsequently cavitates to form the chorionic cavity.
Extraembryonic mesoderm, originating from the cytotrophoblast, fills the space between the trophoblast and Heuser's membrane, and subsequently cavitates to form the chorionic cavity.
The chorionic plate, formed by the extraembryonic somatic mesoderm, is contiguous with the connecting stalk and contributes to the formation of the definitive umbilical cord.
The chorionic plate, formed by the extraembryonic somatic mesoderm, is contiguous with the connecting stalk and contributes to the formation of the definitive umbilical cord.
Primary chorionic villi, extensions of the syncytiotrophoblast, are initially avascular and solely serve to anchor the blastocyst to the endometrium, preceding the establishment of uteroplacental circulation.
Primary chorionic villi, extensions of the syncytiotrophoblast, are initially avascular and solely serve to anchor the blastocyst to the endometrium, preceding the establishment of uteroplacental circulation.
Decidualization, the endometrial response to implantation, is primarily characterized by stromal cell apoptosis and decreased vascular permeability, creating a specialized environment for embryonic development.
Decidualization, the endometrial response to implantation, is primarily characterized by stromal cell apoptosis and decreased vascular permeability, creating a specialized environment for embryonic development.
Implantation bleeding, sometimes occurring around day 13 post-fertilization, is a reliable indicator of pregnancy due to its correlation with significant erosion of maternal spiral arteries by the syncytiotrophoblast.
Implantation bleeding, sometimes occurring around day 13 post-fertilization, is a reliable indicator of pregnancy due to its correlation with significant erosion of maternal spiral arteries by the syncytiotrophoblast.
The connecting stalk, initially anchoring the embryo to the chorionic plate, originates from the epiblast and eventually incorporates the allantois and umbilical vessels.
The connecting stalk, initially anchoring the embryo to the chorionic plate, originates from the epiblast and eventually incorporates the allantois and umbilical vessels.
The secondary yolk sac, formed by day 13, is larger and more functionally significant than the primary yolk sac, providing the primary site of hematopoiesis during early embryonic development.
The secondary yolk sac, formed by day 13, is larger and more functionally significant than the primary yolk sac, providing the primary site of hematopoiesis during early embryonic development.
Gametogenesis in both males and females is a continuous process from puberty onwards, ensuring a constant supply of gametes throughout the reproductive lifespan.
Gametogenesis in both males and females is a continuous process from puberty onwards, ensuring a constant supply of gametes throughout the reproductive lifespan.
The duration of spermatogenesis, from spermatogonium to mature spermatozoa, is approximately 74 days, and the daily sperm production rate is relatively constant, around 300 million spermatozoa per day in a healthy male.
The duration of spermatogenesis, from spermatogonium to mature spermatozoa, is approximately 74 days, and the daily sperm production rate is relatively constant, around 300 million spermatozoa per day in a healthy male.
Oogenesis is characterized by symmetrical cytokinesis during meiotic divisions, resulting in the production of four viable haploid oocytes from each primary oocyte.
Oogenesis is characterized by symmetrical cytokinesis during meiotic divisions, resulting in the production of four viable haploid oocytes from each primary oocyte.
The zona pellucida, a glycoprotein layer surrounding the oocyte, is synthesized exclusively by granulosa cells and persists until implantation is fully complete, protecting the developing embryo.
The zona pellucida, a glycoprotein layer surrounding the oocyte, is synthesized exclusively by granulosa cells and persists until implantation is fully complete, protecting the developing embryo.
Fertilization normally occurs in the uterine isthmus, where sperm capacitation is completed and the oocyte is arrested in metaphase II of meiosis.
Fertilization normally occurs in the uterine isthmus, where sperm capacitation is completed and the oocyte is arrested in metaphase II of meiosis.
The fast block to polyspermy in mammalian fertilization is primarily mediated by a rapid depolarization of the oocyte plasma membrane, preventing further sperm fusion within milliseconds of the first sperm-oocyte contact.
The fast block to polyspermy in mammalian fertilization is primarily mediated by a rapid depolarization of the oocyte plasma membrane, preventing further sperm fusion within milliseconds of the first sperm-oocyte contact.
The formation of male and female pronuclei after fertilization is followed by DNA replication in each pronucleus, and subsequent fusion of these pronuclei initiates the first mitotic division of the zygote.
The formation of male and female pronuclei after fertilization is followed by DNA replication in each pronucleus, and subsequent fusion of these pronuclei initiates the first mitotic division of the zygote.
Blastomeres in the early cleavage embryo are totipotent until the morula stage, meaning any isolated blastomere can develop into a complete embryo and extraembryonic tissues.
Blastomeres in the early cleavage embryo are totipotent until the morula stage, meaning any isolated blastomere can develop into a complete embryo and extraembryonic tissues.
Compaction, a critical step in morula formation, is mediated by the upregulation of N-cadherin and E-cadherin, facilitating tight junctions and gap junction formation between blastomeres.
Compaction, a critical step in morula formation, is mediated by the upregulation of N-cadherin and E-cadherin, facilitating tight junctions and gap junction formation between blastomeres.
The trophoblast lineage, derived from outer cells of the morula, exclusively contributes to the extraembryonic membranes, without any contribution to the embryo proper itself.
The trophoblast lineage, derived from outer cells of the morula, exclusively contributes to the extraembryonic membranes, without any contribution to the embryo proper itself.
The blastocoel, the fluid-filled cavity of the blastocyst, is crucial for providing nutrients to the inner cell mass and facilitating the segregation of the trophoblast from the embryonic disc.
The blastocoel, the fluid-filled cavity of the blastocyst, is crucial for providing nutrients to the inner cell mass and facilitating the segregation of the trophoblast from the embryonic disc.
Apposition, the initial loose attachment of the blastocyst to the endometrium, is mediated by selectin-ligand interactions between trophoblast cells and endometrial epithelial cells.
Apposition, the initial loose attachment of the blastocyst to the endometrium, is mediated by selectin-ligand interactions between trophoblast cells and endometrial epithelial cells.
Invasion of the syncytiotrophoblast into the endometrium is primarily driven by proteolytic enzymes, such as matrix metalloproteinases (MMPs), secreted by the cytotrophoblast.
Invasion of the syncytiotrophoblast into the endometrium is primarily driven by proteolytic enzymes, such as matrix metalloproteinases (MMPs), secreted by the cytotrophoblast.
Decidual cells, transformed endometrial stromal cells, secrete prolactin and relaxin, hormones essential for maintaining early pregnancy and modulating uterine contractility.
Decidual cells, transformed endometrial stromal cells, secrete prolactin and relaxin, hormones essential for maintaining early pregnancy and modulating uterine contractility.
The bilaminar embryonic disc, composed of epiblast and hypoblast, establishes the primary body axes of the embryo, with the epiblast defining the dorsal side and the hypoblast defining the ventral side.
The bilaminar embryonic disc, composed of epiblast and hypoblast, establishes the primary body axes of the embryo, with the epiblast defining the dorsal side and the hypoblast defining the ventral side.
Gametogenesis, encompassing both spermatogenesis and oogenesis, is strictly confined to the gonads, with no documented instances of ectopic gamete production under normal physiological conditions.
Gametogenesis, encompassing both spermatogenesis and oogenesis, is strictly confined to the gonads, with no documented instances of ectopic gamete production under normal physiological conditions.
The initiation of oogenesis in females is a temporally protracted process that commences during fetal development and concludes at the onset of menarche, ensuring a continuous supply of primary oocytes from birth.
The initiation of oogenesis in females is a temporally protracted process that commences during fetal development and concludes at the onset of menarche, ensuring a continuous supply of primary oocytes from birth.
Sertoli cells, pivotal components of the seminiferous tubules, are functionally analogous to follicular cells in the ovary, providing structural and nutritional support to developing germ cells and secreting inhibin to regulate FSH.
Sertoli cells, pivotal components of the seminiferous tubules, are functionally analogous to follicular cells in the ovary, providing structural and nutritional support to developing germ cells and secreting inhibin to regulate FSH.
The acrosome reaction, a prerequisite for successful fertilization, is triggered exclusively by direct contact with the zona pellucida, and is independent of any prior capacitation events within the female reproductive tract.
The acrosome reaction, a prerequisite for successful fertilization, is triggered exclusively by direct contact with the zona pellucida, and is independent of any prior capacitation events within the female reproductive tract.
The zona reaction, characterized by the enzymatic modification of the zona pellucida, serves solely as a polyspermy block, preventing the entry of multiple spermatozoa and ensuring monospermic fertilization.
The zona reaction, characterized by the enzymatic modification of the zona pellucida, serves solely as a polyspermy block, preventing the entry of multiple spermatozoa and ensuring monospermic fertilization.
Following fertilization, the secondary oocyte expeditiously completes meiosis II, invariably resulting in the formation of two polar bodies and a mature ovum, irrespective of sperm penetration.
Following fertilization, the secondary oocyte expeditiously completes meiosis II, invariably resulting in the formation of two polar bodies and a mature ovum, irrespective of sperm penetration.
During spermatogenesis, the interconnectedness of developing spermatogenic cells via cytoplasmic bridges is transient and solely for synchronized meiotic divisions, dissolving completely after the formation of haploid spermatids.
During spermatogenesis, the interconnectedness of developing spermatogenic cells via cytoplasmic bridges is transient and solely for synchronized meiotic divisions, dissolving completely after the formation of haploid spermatids.
The histological architecture of the Graafian follicle is characterized by the absence of the theca interna and theca externa layers, simplifying its structure to membrana granulosa, antrum, and corona radiata.
The histological architecture of the Graafian follicle is characterized by the absence of the theca interna and theca externa layers, simplifying its structure to membrana granulosa, antrum, and corona radiata.
Ovulation is exclusively triggered by a surge in estrogen from the developing follicle, directly stimulating the ovary to release the oocyte, without the involvement of luteinizing hormone.
Ovulation is exclusively triggered by a surge in estrogen from the developing follicle, directly stimulating the ovary to release the oocyte, without the involvement of luteinizing hormone.
Spermatogonia, the progenitor cells of spermatozoa, are situated in the adluminal compartment of the seminiferous tubules, adjacent to the lumen, ensuring their proximity to the site of sperm release.
Spermatogonia, the progenitor cells of spermatozoa, are situated in the adluminal compartment of the seminiferous tubules, adjacent to the lumen, ensuring their proximity to the site of sperm release.
The process of spermiogenesis, transforming spermatids into spermatozoa, involves the addition of substantial cytoplasm and organelles, significantly increasing the size and complexity of the mature sperm cell.
The process of spermiogenesis, transforming spermatids into spermatozoa, involves the addition of substantial cytoplasm and organelles, significantly increasing the size and complexity of the mature sperm cell.
Capacitation, the process by which spermatozoa acquire the capacity to fertilize an oocyte, occurs exclusively in the epididymis, during sperm maturation and storage.
Capacitation, the process by which spermatozoa acquire the capacity to fertilize an oocyte, occurs exclusively in the epididymis, during sperm maturation and storage.
The penetration of the corona radiata by spermatozoa during fertilization is facilitated solely by the mechanical force of sperm motility, requiring no enzymatic action or contribution from the oocyte.
The penetration of the corona radiata by spermatozoa during fertilization is facilitated solely by the mechanical force of sperm motility, requiring no enzymatic action or contribution from the oocyte.
Cortical granules, residing in the oocyte cortex, release their contents into the perivitelline space immediately upon sperm-oocyte fusion, initiating both the zona reaction and the cortical reaction simultaneously.
Cortical granules, residing in the oocyte cortex, release their contents into the perivitelline space immediately upon sperm-oocyte fusion, initiating both the zona reaction and the cortical reaction simultaneously.
The metabolic activation of the oocyte following fertilization is primarily driven by the paternal centrosome introduced by the sperm, which reorganizes the oocyte cytoplasm and initiates the first cleavage division.
The metabolic activation of the oocyte following fertilization is primarily driven by the paternal centrosome introduced by the sperm, which reorganizes the oocyte cytoplasm and initiates the first cleavage division.
During the cleavage stage, the total size of the zygote progressively increases with each mitotic division, resulting in blastomeres that are significantly larger than the original zygote.
During the cleavage stage, the total size of the zygote progressively increases with each mitotic division, resulting in blastomeres that are significantly larger than the original zygote.
The morula stage, characterized by a 'mulberry-like' appearance, typically consists of 32 cells, marking the transition from loosely arranged blastomeres to a compacted structure with tight junctions.
The morula stage, characterized by a 'mulberry-like' appearance, typically consists of 32 cells, marking the transition from loosely arranged blastomeres to a compacted structure with tight junctions.
The blastocyst cavity, or blastocoele, is formed by the active transport of sodium and chloride ions into the intercellular spaces of the morula, drawing water osmotically and creating a fluid-filled space.
The blastocyst cavity, or blastocoele, is formed by the active transport of sodium and chloride ions into the intercellular spaces of the morula, drawing water osmotically and creating a fluid-filled space.
The trophoblast, the outer cell layer of the blastocyst, will exclusively give rise to the embryonic tissues of the fetus, while the inner cell mass contributes solely to the extraembryonic membranes and placenta.
The trophoblast, the outer cell layer of the blastocyst, will exclusively give rise to the embryonic tissues of the fetus, while the inner cell mass contributes solely to the extraembryonic membranes and placenta.
Implantation of the blastocyst into the uterine endometrium typically commences around day 6 or 7 post-fertilization, with the embryonic pole of the blastocyst orienting towards the endometrial epithelium.
Implantation of the blastocyst into the uterine endometrium typically commences around day 6 or 7 post-fertilization, with the embryonic pole of the blastocyst orienting towards the endometrial epithelium.
The syncytiotrophoblast, formed from the cytotrophoblast, is characterized by its multinucleated syncytial nature and its inability to invade the endometrial stroma, limiting implantation to superficial attachment.
The syncytiotrophoblast, formed from the cytotrophoblast, is characterized by its multinucleated syncytial nature and its inability to invade the endometrial stroma, limiting implantation to superficial attachment.
On day 8 post-fertilization, the trophoblast differentiates into the cytotrophoblast and syncytiotrophoblast, and simultaneously, the embryoblast differentiates into the epiblast and mesoblast layers.
On day 8 post-fertilization, the trophoblast differentiates into the cytotrophoblast and syncytiotrophoblast, and simultaneously, the embryoblast differentiates into the epiblast and mesoblast layers.
The amniotic cavity arises within the hypoblast layer on day 8, forming a fluid-filled sac that will eventually surround and protect the developing embryo.
The amniotic cavity arises within the hypoblast layer on day 8, forming a fluid-filled sac that will eventually surround and protect the developing embryo.
Trophoblastic lacunae, appearing on day 9, are initially filled with maternal tissue debris and endometrial secretions, and only later become filled with maternal blood.
Trophoblastic lacunae, appearing on day 9, are initially filled with maternal tissue debris and endometrial secretions, and only later become filled with maternal blood.
The exocoelomic membrane (Heuser's membrane) and the exocoelomic cavity (primitive yolk sac) are derived from the cytotrophoblast cells, lining its inner surface and creating the initial yolk sac.
The exocoelomic membrane (Heuser's membrane) and the exocoelomic cavity (primitive yolk sac) are derived from the cytotrophoblast cells, lining its inner surface and creating the initial yolk sac.
Uteroplacental circulation is established around day 11 and 12 when syncytiotrophoblast erodes maternal sinusoids, allowing maternal blood to flow into the trophoblastic lacunae.
Uteroplacental circulation is established around day 11 and 12 when syncytiotrophoblast erodes maternal sinusoids, allowing maternal blood to flow into the trophoblastic lacunae.
The extraembryonic mesoderm, originating from the inner cell mass, fills the space between the trophoblast and the exocoelomic membrane, contributing to the chorion and other extraembryonic structures.
The extraembryonic mesoderm, originating from the inner cell mass, fills the space between the trophoblast and the exocoelomic membrane, contributing to the chorion and other extraembryonic structures.
The chorionic cavity (extraembryonic coelom) arises from the confluence of large cavities that develop within the extraembryonic splanchnic mesoderm, surrounding the amniotic cavity and yolk sac.
The chorionic cavity (extraembryonic coelom) arises from the confluence of large cavities that develop within the extraembryonic splanchnic mesoderm, surrounding the amniotic cavity and yolk sac.
The connecting stalk, visible by day 13, is derived from the extraembryonic somatic mesoderm and will eventually develop into the umbilical cord, connecting the embryo to the placenta.
The connecting stalk, visible by day 13, is derived from the extraembryonic somatic mesoderm and will eventually develop into the umbilical cord, connecting the embryo to the placenta.
Decidual reaction in the endometrium, a response to implantation, involves a decrease in vascular permeability and stromal cell proliferation to prevent excessive trophoblast invasion.
Decidual reaction in the endometrium, a response to implantation, involves a decrease in vascular permeability and stromal cell proliferation to prevent excessive trophoblast invasion.
Implantation bleeding, occurring around day 13, is a consistent and reliable sign of pregnancy, resulting from the rupture of endometrial capillaries by the invading syncytiotrophoblast.
Implantation bleeding, occurring around day 13, is a consistent and reliable sign of pregnancy, resulting from the rupture of endometrial capillaries by the invading syncytiotrophoblast.
Primary villi, the initial placental structures, are composed of a cytotrophoblast core covered by a syncytiotrophoblast layer, projecting into the trophoblastic lacunae filled with maternal blood.
Primary villi, the initial placental structures, are composed of a cytotrophoblast core covered by a syncytiotrophoblast layer, projecting into the trophoblastic lacunae filled with maternal blood.
The secondary yolk sac, formed around day 13, is smaller and definitive, replacing the larger, transient primitive yolk sac, and is crucial for early hematopoiesis and germ cell origin.
The secondary yolk sac, formed around day 13, is smaller and definitive, replacing the larger, transient primitive yolk sac, and is crucial for early hematopoiesis and germ cell origin.
Spermatozoa, upon entering the female reproductive tract, exhibit immediate fertilizing capacity and can directly interact with the oocyte without undergoing capacitation.
Spermatozoa, upon entering the female reproductive tract, exhibit immediate fertilizing capacity and can directly interact with the oocyte without undergoing capacitation.
Oogenesis in humans results in the production of four viable haploid ova from each primary oocyte that completes meiosis, maximizing reproductive potential.
Oogenesis in humans results in the production of four viable haploid ova from each primary oocyte that completes meiosis, maximizing reproductive potential.
The duration of spermatogenesis, from spermatogonium to mature spermatozoon, is approximately 74 days, and this entire process occurs continuously and uniformly throughout the seminiferous tubules.
The duration of spermatogenesis, from spermatogonium to mature spermatozoon, is approximately 74 days, and this entire process occurs continuously and uniformly throughout the seminiferous tubules.
The primary function of the sperm's middle piece, packed with mitochondria, is to generate ATP necessary for the acrosome reaction and penetration of the zona pellucida.
The primary function of the sperm's middle piece, packed with mitochondria, is to generate ATP necessary for the acrosome reaction and penetration of the zona pellucida.
The corona radiata, zona pellucida, and oocyte plasma membrane represent obligatory barriers that a spermatozoon must sequentially penetrate to achieve successful fertilization.
The corona radiata, zona pellucida, and oocyte plasma membrane represent obligatory barriers that a spermatozoon must sequentially penetrate to achieve successful fertilization.
The fusion of pronuclei, resulting in a diploid zygote nucleus, is immediately followed by the first cleavage division, initiating embryonic development without any intervening period of nuclear quiescence.
The fusion of pronuclei, resulting in a diploid zygote nucleus, is immediately followed by the first cleavage division, initiating embryonic development without any intervening period of nuclear quiescence.
The blastocyst, upon reaching the uterine cavity, strictly maintains its zona pellucida until implantation is complete, preventing premature attachment to the oviductal or endometrial lining.
The blastocyst, upon reaching the uterine cavity, strictly maintains its zona pellucida until implantation is complete, preventing premature attachment to the oviductal or endometrial lining.
Gametogenesis, a pivotal biological process, culminates in the genesis of diploid gametes within the gonadal tissues of sexually reproducing organisms.
Gametogenesis, a pivotal biological process, culminates in the genesis of diploid gametes within the gonadal tissues of sexually reproducing organisms.
Oogenesis, the specialized form of gametogenesis in females, initiates post-pubertally and continues uninterrupted throughout the reproductive lifespan.
Oogenesis, the specialized form of gametogenesis in females, initiates post-pubertally and continues uninterrupted throughout the reproductive lifespan.
Spermatogenesis, the analogous process in males, is characterized by a finite production cycle, concluding at approximately 74 days, after which germinal epithelium becomes quiescent.
Spermatogenesis, the analogous process in males, is characterized by a finite production cycle, concluding at approximately 74 days, after which germinal epithelium becomes quiescent.
Primordial germ cells (PGCs), the progenitors of gametes, originate within the gonadal ridge and subsequently migrate to extragonadal locations to initiate gametogenesis.
Primordial germ cells (PGCs), the progenitors of gametes, originate within the gonadal ridge and subsequently migrate to extragonadal locations to initiate gametogenesis.
In oogenesis, the progression from primordial follicle to Graafian follicle is solely regulated by follicle-stimulating hormone (FSH) in a linear, non-cyclic manner.
In oogenesis, the progression from primordial follicle to Graafian follicle is solely regulated by follicle-stimulating hormone (FSH) in a linear, non-cyclic manner.
The zona pellucida, a critical extracellular matrix of the oocyte, is primarily synthesized by the theca interna cells and is solely composed of sulfated glycosaminoglycans.
The zona pellucida, a critical extracellular matrix of the oocyte, is primarily synthesized by the theca interna cells and is solely composed of sulfated glycosaminoglycans.
Spermiogenesis, the terminal phase of spermatogenesis, involves the meiotic division of spermatocytes into haploid spermatids, which then undergo morphological maturation.
Spermiogenesis, the terminal phase of spermatogenesis, involves the meiotic division of spermatocytes into haploid spermatids, which then undergo morphological maturation.
Capacitation, a prerequisite for fertilization, is a process that occurs in the epididymis and involves the irreversible destabilization of the sperm plasma membrane.
Capacitation, a prerequisite for fertilization, is a process that occurs in the epididymis and involves the irreversible destabilization of the sperm plasma membrane.
The acrosome reaction, triggered by contact with the corona radiata, is characterized by the release of lysosomal enzymes that facilitate sperm penetration through the zona pellucida.
The acrosome reaction, triggered by contact with the corona radiata, is characterized by the release of lysosomal enzymes that facilitate sperm penetration through the zona pellucida.
Fertilization is typically initiated in the uterine isthmus, where the capacitated spermatozoa encounter the oocyte released from the ovary.
Fertilization is typically initiated in the uterine isthmus, where the capacitated spermatozoa encounter the oocyte released from the ovary.
The cortical reaction, a polyspermy block, is mediated by the exocytosis of cortical granules, leading to the inactivation of ZP3 receptors and zona hardening, preventing further sperm entry.
The cortical reaction, a polyspermy block, is mediated by the exocytosis of cortical granules, leading to the inactivation of ZP3 receptors and zona hardening, preventing further sperm entry.
Following fertilization, the secondary oocyte completes meiosis I, resulting in the formation of a mature ootid and the second polar body.
Following fertilization, the secondary oocyte completes meiosis I, resulting in the formation of a mature ootid and the second polar body.
Cleavage divisions, post-fertilization, are characterized by an increase in cytoplasmic volume with each successive mitotic division, leading to exponential growth of the early embryo.
Cleavage divisions, post-fertilization, are characterized by an increase in cytoplasmic volume with each successive mitotic division, leading to exponential growth of the early embryo.
The morula, a 16-cell stage embryo, is characterized by a differentiated inner cell mass (ICM) that will contribute to the trophoblast, and an outer cell mass that will form the embryo proper.
The morula, a 16-cell stage embryo, is characterized by a differentiated inner cell mass (ICM) that will contribute to the trophoblast, and an outer cell mass that will form the embryo proper.
Blastocyst formation is initiated by fluid influx into intercellular spaces within the morula, resulting in the formation of the blastocoel, a fluid-filled cavity.
Blastocyst formation is initiated by fluid influx into intercellular spaces within the morula, resulting in the formation of the blastocoel, a fluid-filled cavity.
Implantation typically commences around day 8 post-fertilization, with the syncytiotrophoblast invading the endometrial stroma and initiating lacunae formation.
Implantation typically commences around day 8 post-fertilization, with the syncytiotrophoblast invading the endometrial stroma and initiating lacunae formation.
The cytotrophoblast, derived from the trophoblast, is characterized by its multinucleated syncytial structure and its role in eroding maternal capillaries to establish uteroplacental circulation.
The cytotrophoblast, derived from the trophoblast, is characterized by its multinucleated syncytial structure and its role in eroding maternal capillaries to establish uteroplacental circulation.
The hypoblast layer, arising from the embryoblast, is composed of columnar cells and contributes to the formation of the amnion and subsequent embryonic tissues.
The hypoblast layer, arising from the embryoblast, is composed of columnar cells and contributes to the formation of the amnion and subsequent embryonic tissues.
Uteroplacental circulation is established around day 11-12, when maternal blood flows into trophoblastic lacunae, initiating the exchange of gases and nutrients.
Uteroplacental circulation is established around day 11-12, when maternal blood flows into trophoblastic lacunae, initiating the exchange of gases and nutrients.
The chorionic cavity, also known as the extraembryonic coelom, is formed by the confluence of lacunae within the extraembryonic somatic mesoderm and encloses the yolk sac and amnion.
The chorionic cavity, also known as the extraembryonic coelom, is formed by the confluence of lacunae within the extraembryonic somatic mesoderm and encloses the yolk sac and amnion.
Flashcards
What are gametes?
What are gametes?
Reproductive cells of the organism containing half of the organism genetic material. Human gametes are sperm and egg
Where do gametes come from?
Where do gametes come from?
Gametes come from gonads which are testes (male) and ovaries (female).
What is gametogenesis?
What is gametogenesis?
Production of gametes involving division and maturation to form haploid gametes with half the chromosomes. Spermatogenesis in males and oogenesis in females
Where does gametogenesis occur?
Where does gametogenesis occur?
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What is fertilization?
What is fertilization?
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Week 3 PGC Migration
Week 3 PGC Migration
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Week 4 PGC Migration
Week 4 PGC Migration
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Week 5 PGC Migration
Week 5 PGC Migration
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Week 6 PGC Migration
Week 6 PGC Migration
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Oogenesis commencement
Oogenesis commencement
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Oocytes at time of birth
Oocytes at time of birth
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Ovarian cycle - follicular phase
Ovarian cycle - follicular phase
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Ovarian Cycle - Ovulation
Ovarian Cycle - Ovulation
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Ovarian Cycle - Luteal Phase
Ovarian Cycle - Luteal Phase
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Primordial Follicles
Primordial Follicles
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Primary Follicles
Primary Follicles
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Secondary Follicle
Secondary Follicle
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Graafian Follicle
Graafian Follicle
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LH Surge
LH Surge
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Corpus Luteum
Corpus Luteum
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follicle stimulating hormone
follicle stimulating hormone
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Luteinizing hormone
Luteinizing hormone
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Estrogen
Estrogen
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Corona Radiata
Corona Radiata
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Granulosa Cells
Granulosa Cells
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Antrum
Antrum
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Cumulus Oophorus
Cumulus Oophorus
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Theca Interna
Theca Interna
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Theca Externa
Theca Externa
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Basal Lamina
Basal Lamina
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Capillaries
Capillaries
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Mature Follicle
Mature Follicle
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Post-Ovulation Changes
Post-Ovulation Changes
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Spermatogenesis
Spermatogenesis
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Mitotic Division in Spermatogenesis
Mitotic Division in Spermatogenesis
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Meiotic Division in Spermatogenesis
Meiotic Division in Spermatogenesis
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Spermiogenesis
Spermiogenesis
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Sertoli Cells
Sertoli Cells
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Leydig cells
Leydig cells
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Sex Cords
Sex Cords
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Fetal Stage: Sex cords
Fetal Stage: Sex cords
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Puberty: Sex Cords
Puberty: Sex Cords
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Type A Dark Spermatogonia
Type A Dark Spermatogonia
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Type A Pale
Type A Pale
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Type B Spermatogonia
Type B Spermatogonia
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PGCs
PGCs
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Cytoplasmic Bridges in spermatogenesis
Cytoplasmic Bridges in spermatogenesis
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Meiosis I
Meiosis I
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Meiosis II
Meiosis II
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Spermiogenesis definition
Spermiogenesis definition
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Acrosome Formation
Acrosome Formation
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Sertoli Cells: Cleaning residual bodies
Sertoli Cells: Cleaning residual bodies
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Spermatogensis - final
Spermatogensis - final
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Spermatogenesis amount
Spermatogenesis amount
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transport
transport
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Cilia Action
Cilia Action
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activation
activation
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Capacitation
Capacitation
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Reaction
Reaction
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corona radiata entry
corona radiata entry
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second shield Zona
second shield Zona
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Fusion
Fusion
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cortical reaction
cortical reaction
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the zona reaction
the zona reaction
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to the fast block
to the fast block
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The metabolism of activation
The metabolism of activation
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Completion, maturation
Completion, maturation
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cell cleavage
cell cleavage
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are termed Morula
are termed Morula
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a blastocyst
a blastocyst
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The is inner stem
The is inner stem
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Endometrium contact
Endometrium contact
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Maternal acceptance:
Maternal acceptance:
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Inner stem
Inner stem
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Invasive syncytiotrophoblast secretes to
Invasive syncytiotrophoblast secretes to
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blasto!
blasto!
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and develops. 9 is when It's closed which.is when
and develops. 9 is when It's closed which.is when
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cavities form
cavities form
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Membrane is formed
Membrane is formed
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Occurs sometimes but.
Occurs sometimes but.
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The cells do develop new
The cells do develop new
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From a connection formed
From a connection formed
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What a are happening?
What a are happening?
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Study Notes
Gametes
- Gametes are reproductive cells, either sperm, or eggs, that contain half the genetic material of an organism.
- During sexual reproduction, gametes combine during fertilization to form a new organism.
Origin of Gametes
- In males, sperm are produced in the testes.
- In females, eggs are produced in the ovaries.
Gametogenesis Definition
- Gametogenesis is the process of producing gametes (sperm and eggs) through the division and maturation of germ cells.
- This process results in haploid gametes, which contain half the usual number of chromosomes.
Types of Gametogenesis
- In males, gametogenesis is called spermatogenesis, resulting in sperm production.
- In females, gametogenesis is called oogenesis, resulting in the production of eggs (ova).
Location of Gametogenesis
- In males, gametogenesis occurs in the testes, specifically within the seminiferous tubules.
- In females, gametogenesis occurs in the ovaries, where eggs are formed in follicles.
Fertilization
- Fertilization is the fusion of a male gamete (sperm) and a female gamete (egg) to form a zygote.
- Typically, fertilization happens in the fallopian tubes, where sperm penetrates the egg, and the combination of genetic material restores the full set of chromosomes.
- This process initiates embryonic development.
Primordial Germ Cell (PGC) Migration Week 3 Embryonic Development
- PGCs originate from the epiblast and migrate to the yolk sac wall near the allantois.
PGC Migration Week 4 Embryonic Development
- PGCs leave the yolk sac and move into the hindgut.
PGC Migration Week 5 Embryonic Development
- PGCs migrate along the dorsal mesentery of the hindgut toward the gonadal ridges.
PGC Migration Week 6 Embryonic Development
- PGCs reach the developing gonads (ovaries or testes).
- They start differentiating into oogonia (in females) or spermatogonia (in males).
Oogenesis Commences Before Birth
- About 2 million primary oocytes are present in the ovaries at birth
- Oocytes are arrested in suspended prophase I of meiosis
- Primary oocytes are not formed after birth
- Approximately 30,000 to 40,000 oocytes remain at puberty
- Only 200-400 oocytes reach full maturity
- Typically, one oocyte is expelled from the ovary every 28 days.
Oogenesis During Fetal Development
- Primordial germ cells (oogonia) multiply rapidly by mitosis inside the developing ovaries. Also, the number of oogonia reaches approximately 7 million.
- Many oogonia undergo atresia (degeneration), resulting in about 2 million primary oocytes remaining by birth.
Oogenesis Before Birth
- Oogonia differentiate into primary oocytes by entering meiosis I
- Primary oocytes become arrested in prophase I of meiosis (specifically in the diplotene stage of prophase I) until puberty
- Oocyte maturation inhibitor (OMI), secreted by surrounding follicular cells, causes this arrest
- Key Point: No new primary oocytes are formed after birth
Oogenesis Puberty-Menopause
- Approximately 30,000 to 40,000 primary oocytes remain due to continued atresia at puberty
- Select group of primary oocytes begins to mature each menstrual cycle under the influence of follicle-stimulating hormone (FSH) from puberty until menopause
- Typically, only one oocyte reaches full maturity per cycle and is ovulated (released from the ovary)
Oogenesis before Ovulation
- Primary oocyte resumes meiosis I under the influence of luteinizing hormone (LH)
- Meiosis I is completed, producing one large secondary oocyte (containing most of the cytoplasm) and One small first polar body, which degenerates
- Secondary oocyte immediately begins meiosis II but becomes arrested in metaphase II
- The arrested secondary oocyte is released from the ovary and enters the fallopian tube.
Oogenesis: If Fertilization Occurs
- Secondary oocyte completes meiosis II
- Processes: A mature ovum (egg) that is capable of fusing with a sperm cell, as well as a second polar body, which degenerates, are produced.
Oogenesis: If Fertilization Does Not Occur
- Secondary oocyte degenerates without completing meiosis II.
Facts on Oogenesis: Number of Oocytes
- Oogenesis produces a limited number of eggs, unlike spermatogenesis.
Facts on Oogenesis: Meiotic Arrests
- Oogenesis includes two arrests: prophase I (before birth until ovulation) and metaphase II (until fertilization)
Facts on Oogenesis: Follicular Development
- Each oocyte is surrounded by granulosa and theca cells, which form a follicle
- Follicular cells secrete hormones which regulate oocyte development.
Facts on Oogenesis: Ovulation Frequency
- Typically, only one oocyte is released per 28-day menstrual cycle
Ovarian Cycle at Puberty
- Ovarian cycle starts at puberty
- Ovarian cycle controlled by hormones
- 15-20 primary follicles develop
- Secondary follicle forms
- Graafian follicle matures
- Ovulation occurs
- Corpus luteum forms
- Corpus albicans forms if fertilization doesn't occur
Ovarian Cycle Regulation
- The ovarian cycle involves the development and release of an oocyte (egg cell)
- Hormonal regulation is necessary for reproduction
- Three main phases: follicular phase, ovulation, and luteal phase
Follicular Phase
- Days 1-14
- The ovarian cycle, which is controlled by FSH and LH, starts with the onset of puberty
- The anterior pituitary gland produces FSH and LH
- FSH stimulates Primordial follicles
- Immature oocyte contained in thousands of primordial follicles in ovaries at birth
- Primary follicles (15–20 per cycle)
- Oocyte comprised of each follicle that develops under the influence of FSH surrounded by granulosa cells
- Secondary follicle
- Enlarge fluid-filled cavity called the antrum contained in fluid secondary follicle
- Graafian follicle (mature follicle)
- Dominant follicle matures into a Graafian follicle, while the rest undergo atresia (degeneration) that Dominant follicle prepares for ovulation
Ovulation Timing and Process
- Around day 14 of menstrual cycle
- A LH surge triggers ovulation
- Graafian follicle ruptures and releases the oocyte into the fallopian tube
- Released oocyte is prepared for fertilization.
Luteal Phase
- Days 15-28
- The ruptured follicle transforms into the corpus luteum
- The corpus luteum maintains the uterine lining in preparation for possible pregnancy by secreting progesterone and some estrogen
- Corpus albicans occurs if fertilization isn't successful; a fibrous scar-like tissue leading to a drop in hormone levels causing menstruation to begin
- Corpus luteum continues to produce hormones to support early pregnancy until the placenta takes over if fertilization occurs
Ovarian Cycle Hormonal Control
- Follicular growth stimulated by FSH in the early phase
- Ovulation and corpus luteum formation triggered by LH
- Endometrial proliferation aided by Estrogen, produced by the developing follicle
- Crucial for maintaining the uterine lining is Progesterone, produced by the corpus luteum
Ovarian Structures: Oocyte
- Located at the center (within the cumulus oophorus).
- Plays a crucial role in fertilization
- Surrounded by the zona pellucida which is a glycoprotein layer
- Surrounded by the corona radiata
- Innermost layer of granulosa cells
- Remains attached to the oocyte after ovulation
Ovarian Structures: Granulosa Cells
- Multiple layers surrounding the antrum and the oocyte
- Conversion of androgens (produced by theca interna cells into estrogens via the enzyme aromatase
- Aromatase production stimulated by Follicle-Stimulating Hormone (FSH). The cells also play a vital role in estrogen production.
Ovarian Structures: Antrum
- Large fluid-filled space that develops as the follicle matures that contains hormones, growth factors, and nutrients necessary for oocyte maturation
- Increases in size as the follicle reaches ovulatory maturity
Ovarian Structures: Cumulus Oophorus
• A specialized cluster of granulosa cells that surrounds the oocyte and extends into the antrum, and that Provides support and signaling for the oocyte
Ovarian Structures: Theca Layers (Interna)
- Outer layers of the follicle are divided into two distinct regions
- Highly vascularized, and contains steroidogenic cells
- Produce androgens
- Responds to Luteinizing Hormone (LH) ,which are later converted into estrogens by granulosa cells, which also stimulates androgen production
Ovarian Structures: Theca Layers Externa
- Outer layers of the follicle are divided into two distinct regions
- Composed of connective tissue and smooth muscle cells, and provides structural support to the follicle
Ovarian Structures: Basal Lamina
- A thin layer separating the granulosa cells from the theca interna
- Maintains the distinct functions of granulosa and theca cells, preventing blood vessels from penetrating the granulosa layer
Ovarian Structures: Capillaries
- Found in the theca interna, providing blood supply and nutrients to the growing follicle. The granulosa layer itself is avascular (lacking blood vessels), relying on diffusion for nutrient exchange.
Ovarian Structure's Physiological Significance
It represents the mature follicle ready for ovulation. Graafian follicle ruptures, releasing the oocyte into the fallopian tube (under the influence of a surge in LH during ovulation) Remaining follicular structure transforms into the corpus luteum Corpus luteum secretes progesterone to support the luteal phase of the ovarian cycle The structure plays a crucial role in female fertility, and ensures: Proper development & Ensures the release of an egg for potential fertilization
Follicular Development in the Ovary Step 1
• Early Primary Follicle: Small follicles containing immature oocytes start to develop.
Follicular Development in the Ovary Step 2
• Growing Follicle: The follicle enlarges and begins accumulating fluid.
Follicular Development in the Ovary Step 3
• Secondary Follicle: The follicle continues growing, and the oocyte undergoes further maturation.
Follicular Development in the Ovary Step 4
• Follicle Approaching Maturity: As the follicle grows, it reaches a stage where it is ready to release the oocyte.
Follicular Development in the Ovary Step 5
• Mature Follicle (Graafian Follicle): This is the final stage of follicular development before ovulation.
Key Process for Ovulation
• Around the middle of the menstrual cycle, a surge in Luteinizing Hormone (LH) triggers ovulation.
- A secondary oocyte is released into the fallopian tube as Mature follicle ruptures
- The released oocyte is ready for fertilization
Post-Ovulation Ovarian Changes
• The empty follicle transforms into the corpus luteum.
- corpus luteum secretes progesterone to maintain the uterine lining
- If fertilization does not occur, the corpus luteum degenerates into the corpus albicans.
Oocyte's Journey
• The fimbriae at the end of the fallopian tube help sweep the oocyte into the tube
- The oocyte moves through the tube toward the uterus.
Fertilization
• If sperm meets the oocyte in the fallopian tube, fertilization occurs, forming a zygote.
- The zygote undergoes multiple cell divisions, forming a two-cell stage, four-cell stage, and eight-cell stage.
- The developing embryo progresses to the morula stage and then becomes a blastocyst.
Implantation
• The blastocyst reaches the uterus and implants into the endometrium, leading to pregnancy. • If fertilization does not occur, the oocyte degenerates, and menstruation follows.
Spermatogenesis Summary
• Sperm cells (spermatozoa) develop from precursor cells (spermatogonia) within the seminiferous tubules of the testes. • This process takes approximately 74 days and produces around 300 million sperm per day. • Essential for male fertility, the process involves cellular transformations, supporting cells, and hormonal regulation
Spermatogenesis Phase 1
• Mitotic division (Spermatogonial Phase) • Diploid germ cells (2n) produce primary spermatocytes via spermatogonia after undergoing mitotic division located close to the basal membrane of the seminiferous tubules
- Preserves reliable quantity of precursor cells
Spermatogenesis Phase 2
• Meiotic division (Spermatocyte Phase) - Primary spermatocytes (2n) give rise to secondary spermatocytes (haploid, n)
- By undergoing first first meiotic division (Meiosis 1)
- Quickly producing spermatids (haploid, n) (Secondary spermatocytes enter second meiotic division (Meiosis II))
- By ensures genetic diversity through recombination and chromosome reduction
Spermatogenesis Phase 3
• Spermiogenesis (Differentiation Phase)
-
Spermatids undergo morphological changes to become spermatozoa (mature sperm), such as undergoing:
-
Formation of the acrosome (enzymes for egg penetration).
-
Condensation of nuclear material.
-
Development of the flagellum for motility.
-
Loss of excess cytoplasm (cytoplasmic remodeling)
-
Result: Spermatozoa are then released into the lumen of seminiferous tubules and transported to the epididymis for final maturation.
Supporting Cells: Sertoli cells
· Provide structural and metabolic support to develop sperm · Secrete androgen-binding protein (ABP) (High local concentrations of testosterone which is necessary for sperm development is maintained by binding ABP) · Regulate follicle-stimulating hormone (FSH) Phagocytose residual cytoplasm during spermiogenesis; Release inhibin (FSH secretion) Protect sperm from immune attacks & blood testes barrier is formed
Supporting Cells: Leydig cells
· Leydig cells are located on the interstitial space outside the seminiferous tubules · Produce testosterone in response to luteinizing hormone (LH) · Testosterone is essential for spermatogenesis and secondary sexual characteristics
Male Gonad Development
· Fetal stages with solid immature sex cords and PGCs
· Transformation at puberty into hollow seminiferous tubules · Contains; Dormant spermatogonia from primordial germ cells Immature support cells
Sex Cords Formation
• embryonic structures in the developing gonads (testes in males, ovaries in females) that give rise to the reproductive tissues responsible for gamete (sperm or egg) production.
Male Tests Stages
- Early Embryonic Stage:
- Formation of sex cords that are occupied by migration germ cells (PGCs) from yolk sac
- Trigger of expression of SRY gene that determines testis development in embryo
- Fetal stage:
- Solid sex cords that occupied with spermatogonia, and sertoli
- Not yet functional for sperm production
- At puberty:
- Transformed by sex cords with seminiferous tubules, in charge of sperm production
- Sertoli is supported by Leydig-Essential
Key Functions of Sex Cords
Serve as the essential structure for future fertility for both sexes (testies + sperm, egg+ ovaries ) • Protected the environment • Production of gametes of testis ( Seminepherous tubules) Ovaries ( Follicles
Sertoli Cell Maturation
- Fully mature sex cords become hollow to form the seminiferous tubules and form the blood-testis barrier protecting sperm cells from immune attacks
Steroli and Leydig cells with Sperm Production
- Spermatogonia (dormant cells) begin deviding to produce sperm
- Sertoli cells support sperm development by: Production of Leyding cells with testosterone, nutrients, and hormones
hormonal regulation of spermatogenesis (Gonadotropin-releasing hormone (GnRH))
- The process of this occurs by hypothalamic release to generate pituitary glands-Luteinizing Hormone (releasing testostrone) & Follicle-Stimulating Factors (spermatogenesis production )
Negative/Positive feedBack with Testostrone Production
- Steroli produce inhibin factor which helps regulate levels/secrete of (FSH) at the same time of sperm regulation to enhance its maturation for further development.
- Under the process of spermiogenesis- Sperm sheds excess/ discard (cytoplasm waste)- Sterloli also takes over by assisting in the proper clean and functional cycle that will lead to a properly created sperm which then will begin phagosyting.
Type A Dark Spermatogonia
serve as reserve stem cells for sperm production Rarely divide, primarily to replenish the spermatogonial pool Are Capable of self-renewal, ensuring continuous sperm production throughout life
Type A Pale Spermatogonia
act as progenitor cells that will eventually form sperm Undergo mitotic divisions to amplify the number of spermatogonia before differentiation Do not self-renew but instead produce Type B spermatogonia, which commit to spermatogenesis. Continue dividing mitotically until they transition into Type B spermatogonia
Type B Spermatogonia – The Final Stage Before Meiosis
Undergo one final mitotic division, then differentiate into Primary
- Spermatocytes (which enter meiosis)
Summary of spermatogonia types transition
- Type A dark cells act as a reserve, ensuring sperm production never stops.
- Type A pale cells divide more actively, expanding the population.
- Type B spermatogonia are the last step before entering meiosis
Spermatogica Summary
- Stem Cell production
- Type a dark- Maintains self -Type as pale differentiate and direct
- type B- diplod with produces process for mitosis to produce primary spermatocytes
Pro Spermatocyte
4 major phases
- 1st- Meisosis with primary and chromosomes - Sperate from the pair - reducing the chromosomes number. -2nd - meosis cells seperates at hapoid- leading unique chromosomes -3 rd transforms into sperm (Spermatogenesis) to go through the process through (acrosomes and tails - -4th- The final development - into fully function spermatoza release inside the sperm and gains motility ability
- Cytopasmic Bridge - Help connect each other through process
- Reduciton in chromosomes - Meiosis - helps
- Final Product is the mature spermatoza- eggs are for fertilization and devlipment to have it done
Final differentiation that needs to be a completion cycle of sperm cells
- Keeps the cell till the right stage that help produce material
-Helps reduction in cell number
- The spermatids to fully convert into the cells through (process)
-cytopasmic bridges- keeps them connected
- reduction of chromosomes to from haipode and -The finshied productions are mature sprem and eggs fertilization
How Cytoplasmic function inside the production cycle?
Helps provides it so sperm cells stay and share to helps production Main function - sperm cells that contain the xy or y chromosomes ( which will lack many gene structure needed for help develop -Ctyosplasim helps ensure both cells are healthy and proper developed +Suppoet materials need to function and transfers during to help both mature well to survive, while the maturation provides efficiency to the process the proper cycle!
SpermioGenesis phases and components
Is the final step cycle production that turns speramtiods into cells, for fertilization.
- The essential of it all*
- Acrosomes - for egg, need to penatrate -Nuculis- Compact -Motiltly for Tail and function - Remove cytoplasm production To sum! - it transfers, but that helps promote (motilit) then the mitochondria functions.
- it forms centrioles in swims.
Primary Spermatid
: * (stage A)
The cell is round and undifferentiated
The process of it : : * (stage B)
- Acrosomal, the enlarges - Condesin becomes increase ( Hydrodynamic efficient - Accumulate mitchonira - to help supply the proper energy production
Sperm Development: Final Product
The sperm consits of 3 main points - - the acrosomes and paternal head with chromo --- Midpiece that is used pack mitochondrial with atp and functions in movements/functionality of sperm ---Tail also known a flagulla: is used for motility to produce (long which motility) + shedding the excess, (helps help sertoil cells as its support for waste by that removal for full function)
Spermatogenesis Stage
- Step 1 Seminiferous tubules + Sertoli’s
- stem cells- 2.N (spermaticogonia) 3.Speratorycist 3rd is second : helps to increase genetic Diversity by DNA Recom
- Spermatozoa
- Finalizes through Lumen to gain support and helps produce hormone, which then leads for the cycle of fertilization that can sustain Sertoli’s cells
- Help structural -Nutrients Engulft the waste support
- Support and regulate - Sertoli (sustain for waste + nutrients) and Leading cells to develop . Leyding - Testrone - The two work hand and give power by testrone as needed to assist with fertilization of the egg.
Sperm Movement
- muscle contraindications by - Protagldlands/oxylotion that help travel with the flaggelum
- activation then - - temporary unmovemt/imolbilzea until egg release after ovulation to go into high active -then through chematrtacts that the a zone and then after to get into the sperm then to produce.
Sperm Transport to Eggs
- Prostaglandins in seamen and oxytocin in sperm aids Contractions
- the tail or flagela helps swims with
- Ciliary lining helps transports aid function then aids the eggs
Capacitation
- Occurs inside female productive system
- 5-6 hours
- Secretions alteration with membrane and the
- process happens · Membrane o Glycoproteins o Increases the proper environment that the body needs to support production.
The 2 phases (important reminder of sperm process)
1, to the capacitation that occurs side the female body
- process for high productivity of fertilizes it with that to be able transfer and change its for, 2, acrosome production . : is important for glyco the production through process inside a zpz- for egg productions. This all for that - will be a the
Key Components of A ZP process to lead to sperm production
A hydro enzyme - are produced for the main important factors need. the two key that needs to get there is the . Hallayonis enzyme- . Zone are needed
- to go for that action to be a possibility for it to form + (membrane fusion/and sperm and help it activate)
KeyPoints for Egg and Sperm
-
- Egg production /Fertilizers for for the egg . to then 2 different product that helps ensure it with one production of that helps the prevent of other for that 1 cell
Summary Process
- Corona
-The enzyme release digest for the cells
And there cell is help generate for 3, helps
- for each step help for final step
The Cortical Process. (Sperm & Egg)
- is protective, and needs to perverted for multiplly Ca= helps active and relase - while there is for that important part to do and helps from to - And helps prep
Slow Block Process.
That are not able for the right number the process will not get enough cell and will cause to the
- 8 or more has the highest. The 3, will give the body to get the more genetic stability as need for it to to be to for the development and it
- *this includes the 1 to
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