Biology Chapter on Chromosomal Abnormalities
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Questions and Answers

What is the term for the presence of an abnormal number of chromosomes?

  • Diploidy
  • Aneuploidy (correct)
  • Haploidy
  • Polyploidy

Which of the following is an example of a chromosomal abnormality that results from trisomy?

  • Prader-Willi syndrome
  • Down syndrome (correct)
  • Klinefelter syndrome
  • Turner syndrome

What is the main process that occurs in gamete precursors and gametes before fertilization?

  • Meiosis only
  • Mitosis only
  • Mitosis followed by meiosis (correct)
  • Meiosis followed by mitosis

What is the condition in which the normal separation of chromosomes in meiosis does not occur?

<p>Nondisjunction (A)</p> Signup and view all the answers

Which of the following is a common cause of miscarriage?

<p>Errors in meiosis (D)</p> Signup and view all the answers

What is the correct sequence of events in sexual reproduction?

<p>Gamete formation, fertilization, zygote formation (B)</p> Signup and view all the answers

Which of the following is NOT a chromosomal abnormality mentioned in the text?

<p>Klinefelter Syndrome (A)</p> Signup and view all the answers

What is the genetic makeup of a zygote?

<p>Diploid (C)</p> Signup and view all the answers

What are the two processes that sperm must undergo in the female reproductive tract before they can fertilize an oocyte?

<p>Capacitation and Acrosome reaction (C)</p> Signup and view all the answers

Which of the following is NOT a barrier that protects the oocyte during fertilization?

<p>Uterine lining (A)</p> Signup and view all the answers

What is the name of the layer of glycoproteins surrounding the oocyte?

<p>Zona pellucida (B)</p> Signup and view all the answers

What is the name of the condition where a man produces very few sperm?

<p>Oligospermia (C)</p> Signup and view all the answers

Which of the following is a correct statement about fertilization?

<p>Fertilization occurs in the fallopian tube. (B)</p> Signup and view all the answers

During capacitation, what is removed from the surface of the sperm?

<p>Glycoprotein coat and seminal proteins (C)</p> Signup and view all the answers

The acrosome reaction is triggered by:

<p>Contact with the zona pellucida (A)</p> Signup and view all the answers

What is the name of the structure in the sperm's head that contains enzymes for penetrating the zona pellucida?

<p>Acrosome (A)</p> Signup and view all the answers

What happens to the oocyte immediately after fertilization?

<p>It completes the second meiotic division. (A)</p> Signup and view all the answers

Which hormone is responsible for the contraction of uterine muscles during the transportation of spermatozoa?

<p>Oxytocin (A)</p> Signup and view all the answers

What structure is formed when a cell has two pronuclei?

<p>Zygote (D)</p> Signup and view all the answers

What is a common cause of infertility in women?

<p>Absence of ovulation (B)</p> Signup and view all the answers

What phase of the menstrual cycle involves the shedding of the endometrium?

<p>Menstrual phase (D)</p> Signup and view all the answers

During which phase does the endometrium thicken and renew after the previous cycle?

<p>Proliferative phase (B)</p> Signup and view all the answers

What is a characteristic of male infertility?

<p>Insufficient numbers of sperm and/or poor motility (B)</p> Signup and view all the answers

What layer of the endometrium is responsible for shedding during the menstrual phase?

<p>Functional layer (B)</p> Signup and view all the answers

What hormonal phase occurs after ovulation, preparing the body for possible implantation?

<p>Luteal phase (C)</p> Signup and view all the answers

What is the volume range of a normal ejaculate?

<p>2 to 6 ml (C)</p> Signup and view all the answers

What is the primary function of primordial germ cells (PGCs)?

<p>To migrate to the developing gonads and form gametes (A)</p> Signup and view all the answers

Which of the following best describes gametogenesis?

<p>The biological process that produces haploid cells through cell division and differentiation (A)</p> Signup and view all the answers

At what stage do primordial germ cells (PGCs) begin to migrate to the developing gonads?

<p>Between the fourth and sixth weeks of development (B)</p> Signup and view all the answers

What is the reproductive outcome of spermatogenesis in males?

<p>Four haploid spermatids are produced from each primary spermatocyte (D)</p> Signup and view all the answers

Which type of cells provides support to developing gametes during spermatogenesis?

<p>Sertoli cells (A)</p> Signup and view all the answers

What characterizes teratomas in the context of germ cells?

<p>They can contain a variety of tissues, reflecting pluripotent stem cells (B)</p> Signup and view all the answers

What is the main event that occurs during spermiogenesis?

<p>Formation of the acrosome (B)</p> Signup and view all the answers

Why are pregnancies at higher risk for mothers aged 35 and older?

<p>Because of increased incidence of trisomy and other genetic abnormalities (C)</p> Signup and view all the answers

What is the haploid chromosome number produced in gametes?

<p>23 chromosomes (C)</p> Signup and view all the answers

At what stage do primary oocytes remain arrested until puberty?

<p>Prophase I (C)</p> Signup and view all the answers

What hormone primarily influences the growth and maturation of follicles?

<p>FSH (Follicle stimulating hormone) (B)</p> Signup and view all the answers

During the ovarian cycle, what happens to the Graffian follicle at ovulation?

<p>It ruptures to release a secondary oocyte (B)</p> Signup and view all the answers

What is the composition of the products formed after the completion of meiosis I in oogenesis?

<p>One haploid secondary oocyte and one polar body (C)</p> Signup and view all the answers

What occurs if fertilization does not happen after a secondary oocyte is released?

<p>It will degenerate within 24 hours (A)</p> Signup and view all the answers

How many germ cells are estimated to be present at birth?

<p>700,000 (C)</p> Signup and view all the answers

What consequence does the presence of only 10 million live sperms per ml have for a male partner seeking fertility assistance?

<p>Suggests potential infertility issues (C)</p> Signup and view all the answers

What happens to the endometrium if pregnancy does not occur?

<p>The apical 2/3 of the endometrium sheds while the basal 1/3 stays. (B)</p> Signup and view all the answers

During which phase of the menstrual cycle does the endometrium prepare for potential implantation?

<p>Secretory phase (B)</p> Signup and view all the answers

What structure is formed from the outer cell mass of the blastocyst?

<p>Placenta (B)</p> Signup and view all the answers

What is the primary role of the trophoblast after implantation?

<p>To form the placenta. (B)</p> Signup and view all the answers

Where does implantation of a blastocyst occur?

<p>In the endometrium of the uterus (A)</p> Signup and view all the answers

What replaces the endometrium after implantation occurs?

<p>Decidua (A)</p> Signup and view all the answers

What indicates the beginning of the menstrual cycle?

<p>The first day of menstrual bleed (A)</p> Signup and view all the answers

During which week does implantation of the embryo occur?

<p>Week 2 (B)</p> Signup and view all the answers

What happens to the zona pellucida during the development of the blastocyst?

<p>It gradually degenerates and disappears. (A)</p> Signup and view all the answers

What type of pregnancy occurs when implantation takes place outside the uterus?

<p>Ectopic pregnancy (D)</p> Signup and view all the answers

What is the likely reason behind the higher pregnancy risks for women aged 35 and older?

<p>All of the above (D)</p> Signup and view all the answers

Which of the following is NOT a characteristic of primordial germ cells (PGCs)?

<p>They differentiate directly into mature gametes. (A)</p> Signup and view all the answers

What is the main function of Sertoli cells in spermatogenesis?

<p>To provide nutritional support and structural integrity for developing sperm cells. (B)</p> Signup and view all the answers

What is a key difference between spermatogenesis and oogenesis?

<p>Spermatogenesis produces four functional sperm cells, while oogenesis produces only one functional egg cell. (B)</p> Signup and view all the answers

What is the significance of the term 'pluripotent' when describing germ cells in the context of teratomas?

<p>These cells can differentiate into any type of cell within the body, including reproductive cells. (B)</p> Signup and view all the answers

What is the primary trigger for the acrosome reaction, a crucial step during fertilization?

<p>The binding of the sperm to the zona pellucida. (C)</p> Signup and view all the answers

Which of the following is NOT a direct consequence of the presence of only 10 million live sperms per ml in a man seeking fertility assistance?

<p>Difficulty in achieving and maintaining an erection. (D)</p> Signup and view all the answers

Which of the following is NOT a direct consequence of insufficient numbers of sperm or poor motility in males?

<p>Increased risk of chromosomal abnormalities in offspring. (D)</p> Signup and view all the answers

During which phase of the menstrual cycle is the endometrium most prepared for potential implantation if pregnancy occurs?

<p>Secretory phase (C)</p> Signup and view all the answers

Which of the following factors is NOT a fundamental requirement for successful fertilization?

<p>Successful implantation of the blastocyst. (A)</p> Signup and view all the answers

If a woman does not get pregnant after a secondary oocyte is released, what happens to the endometrium?

<p>It is shed during the menstrual phase. (A)</p> Signup and view all the answers

Which of the following statements accurately reflects the relationship between the endometrium and the menstrual cycle?

<p>The functional layer of the endometrium is shed during the menstrual phase, while the basal layer remains intact to regenerate the functional layer. (D)</p> Signup and view all the answers

Which of the following is the most direct consequence of the absence of ovulation for a woman?

<p>Reduced likelihood of successful fertilization. (A)</p> Signup and view all the answers

Which of the following is a true statement about the relationship between the sperm count and male fertility?

<p>While 20 million sperms per ml is considered the minimum for fertility, a sperm count of 50 million per total ejaculate is often more favorable. (D)</p> Signup and view all the answers

Which statement accurately reflects a common cause of infertility in women?

<p>Pelvic inflammatory disease can lead to occluded uterine tubes, hindering sperm travel. (B)</p> Signup and view all the answers

What is the primary role of the syncytiotrophoblast during the formation of the uteroplacental circulation?

<p>It erodes the endothelial lining of maternal capillaries. (C)</p> Signup and view all the answers

Which of the following is NOT directly involved in the formation of the placenta?

<p>Amnion (D)</p> Signup and view all the answers

What is the significance of the lacunae appearing in the syncytiotrophoblast at day 9 of development?

<p>They form the initial connection between the maternal and fetal circulations. (B)</p> Signup and view all the answers

Which of the following is TRUE about the placenta's role in waste elimination?

<p>The placenta plays a critical role in eliminating fetal waste products, primarily through the mother's blood supply. (A)</p> Signup and view all the answers

What is the PRIMARY function of the chorionic villi?

<p>Facilitating the exchange of nutrients and gases between the mother and the fetus. (B)</p> Signup and view all the answers

What is the relationship between the decidua capsularis and the conceptus?

<p>The decidua capsularis is a layer of the decidua that covers the conceptus. (A)</p> Signup and view all the answers

During the early development of the uteroplacental circulation, what is the most critical factor that allows maternal blood to enter the lacunar system?

<p>The erosion of the maternal capillary lining by the syncytiotrophoblast. (D)</p> Signup and view all the answers

Which of the following is the most accurate description of the relationship between the placenta and the maternal decidua?

<p>The placenta is an integral part of the decidua, formed by the interaction of fetal and maternal tissues. (A)</p> Signup and view all the answers

Which region of the decidua is responsible for forming the maternal part of the placenta?

<p>Decidua basalis (B)</p> Signup and view all the answers

What is the primary function of the syncytiotrophoblast in relation to the endometrium?

<p>It invades the endometrial tissue, enabling the blastocyst to implant. (C)</p> Signup and view all the answers

Which of the following is a key function of the placenta that directly contributes to fetal development?

<p>The placenta synthesizes and secretes essential hormones for fetal growth and development, such as progesterone and estrogen. (D)</p> Signup and view all the answers

Which of the following membranes directly contacts the amnion to form the amniochorionic membrane?

<p>The chorion (D)</p> Signup and view all the answers

What is the primary function of the human chorionic gonadotropin (hCG) produced by the syncytiotrophoblast?

<p>It maintains hormonal activity of the corpus luteum during pregnancy. (C)</p> Signup and view all the answers

After implantation, which structure replaces the uterine endometrium?

<p>The decidua (A)</p> Signup and view all the answers

What is the structure that lines the entire uterine cavity during early development?

<p>Chorion (D)</p> Signup and view all the answers

Which of the following is NOT a region of the decidua?

<p>Decidua chorionica (B)</p> Signup and view all the answers

What is the primary function of the spiral arteries in the maternal part of the placenta?

<p>To transport oxygenated blood from the mother to the fetus. (A), To transport nutrients from the mother to the fetus. (D)</p> Signup and view all the answers

What component of the fetal/placental barrier is responsible for the selective exchange of gases, nutrients, and waste products between the maternal and fetal blood?

<p>The syncytiotrophoblast. (A)</p> Signup and view all the answers

Which of these structures is NOT directly involved in the formation of the chorion, the fetal part of the placenta?

<p>Decidua (D)</p> Signup and view all the answers

What is the primary function of the amnion in relation to the placenta?

<p>To provide a cushion for the developing fetus. (B)</p> Signup and view all the answers

In the context of the placenta, what are cotyledons?

<p>The functional units of the chorion, formed by the branching of the villi. (A)</p> Signup and view all the answers

Compared to secondary villi, tertiary villi are characterized by the presence of:

<p>Blood capillaries in the mesoderm. (C)</p> Signup and view all the answers

What is the primary reason why the placenta is considered a vital organ for fetal development?

<p>It enables the exchange of gases, nutrients, and waste products between the mother and fetus. (B)</p> Signup and view all the answers

What is the clinical term for the condition arising from a fertilized ovum losing its nucleus and being fertilized by one or two sperm?

<p>Gestational Trophoblastic Disease (B)</p> Signup and view all the answers

If implantation occurs, during which phase of the menstrual cycle does the endometrium transform into decidua?

<p>Secretory phase (C)</p> Signup and view all the answers

During which stage of development does the blastocoel appear, marking the transition from morula to blastocyst?

<p>Day 4 after fertilization (D)</p> Signup and view all the answers

What differentiates the outer layer of the trophoblast, the syncytiotrophoblast, from the inner layer, the cytotrophoblast?

<p>The syncytiotrophoblast lacks a cell membrane, while the cytotrophoblast has a cell membrane. (A)</p> Signup and view all the answers

What specific characteristic of the syncytiotrophoblast allows for the establishment of a primitive utero-placental circulation?

<p>Its ability to actively migrate and invade the maternal tissues. (D)</p> Signup and view all the answers

Which of the following is NOT a direct consequence of the differentiation of the inner cell mass (embryoblast) in the second week of development?

<p>Formation of the syncytiotrophoblast. (C)</p> Signup and view all the answers

What is the primary function of the placenta in a pregnancy?

<p>Facilitating nutrient and gas exchange between the mother and the embryo. (D)</p> Signup and view all the answers

Which of the following correctly describes the relationship between the trophoblast and the placenta?

<p>The trophoblast contributes to the formation of the placenta, but it is not the only source. (C)</p> Signup and view all the answers

What is the significance of the chorionic cavity in embryonic development?

<p>It surrounds the amniotic cavity. (D)</p> Signup and view all the answers

What is the correct sequence of events that occur during implantation?

<p>Attachment of the blastocyst to the endometrial epithelium, blastocyst penetration of the endometrium, proliferation and differentiation of the trophoblast. (D)</p> Signup and view all the answers

How does the degeneration of the zona pellucida facilitate implantation?

<p>It exposes the inner cell mass (embryoblast) to direct contact with the endometrial epithelium. (C)</p> Signup and view all the answers

Flashcards

Gametogenesis

The process by which male and female gametes are formed.

Fertilization

The fusion of male sperm and female ovum to form a zygote.

Meiosis

A type of cell division that reduces the chromosome number by half to form gametes.

Aneuploidy

A condition involving an abnormal number of chromosomes in a cell.

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Nondisjunction

The failure of chromosome pairs to separate properly during meiosis.

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Trisomy

A genetic condition of having three copies of a chromosome instead of two.

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Down Syndrome

A genetic disorder caused by trisomy of chromosome 21.

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Ectopic Pregnancy

A pregnancy that occurs outside the uterus, often in a fallopian tube.

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Spermiogenesis

Process transforming spermatids into spermatozoa through various changes.

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Acrosome formation

The development of a cap over the nucleus in sperm, aiding in fertilization.

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Meiosis I in Oogenesis

Primary oocytes undergo meiosis I, halting at prophase I until puberty.

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Follicle Growth

The maturation of ovarian follicles under the influence of FSH hormone.

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Ovulation

Release of a secondary oocyte from the Graafian follicle under LH influence.

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Secondary oocyte

Haploid cell formed from primary oocyte, ready for fertilization.

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Polar body

A small, nonfunctional cell produced during meiosis, receiving little cytoplasm.

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Oocyte arrest

Secondary oocyte halts at metaphase II until fertilization occurs.

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Zygote

The cell formed by the fusion of two pronuclei after fertilization.

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Menstrual Cycle

The regular natural change that occurs in the female reproductive system, including phases of bleeding and preparation for pregnancy.

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Endometrium

The inner lining of the uterus that thickens in preparation for possible implantation of an embryo.

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Proliferative Phase

The phase in the menstrual cycle where the endometrium thickens and prepares for potential implantation.

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Secretory Phase

The phase of the menstrual cycle following ovulation, preparing the endometrium for implantation.

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Menstrual Phase

The phase when the endometrium sheds its functional layer, resulting in menstrual bleeding.

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Basal Layer

The deeper layer of the endometrium that remains intact during the menstrual cycle.

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Ovarian Cycle

The cycle of changes in the ovaries that coincide with the phases of the menstrual cycle, involving egg maturation and release.

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Oogenesis

The process of producing egg cells (ova) from oogonia in the female ovary.

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Primordial Germ Cells (PGCs)

The initial cells that develop into gametes, formed in the epiblast and migrate to the gonads.

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Sertoli Cells

Supportive cells in the testis that nurture developing sperm during spermatogenesis.

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Teratomas

Tumors that can contain various types of tissues and originate from germ cells, indicating pluripotent capability.

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Germ Cells

Cells that give rise to gametes and can differentiate into various cell types during development.

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Oligospermia

A condition characterized by low sperm count in semen.

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Azoospermia

A condition where no sperm is present in the semen.

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Aspermia

The absence of semen during ejaculation.

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Hypospermia

A condition of having low volume of semen during ejaculation.

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Oocyte

The female gamete that is released during ovulation.

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Coronary radiata

A layer of granulosa cells surrounding the oocyte.

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Capacitation

The process that sperm undergo to become capable of fertilizing an egg.

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Acrosome reaction

The process allowing sperm to penetrate the zona pellucida of the egg.

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Zona pellucida

The thick outer layer surrounding the oocyte.

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Fertilization phases

Three steps: penetration of corona radiata, zona pellucida, and membrane fusion.

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Endometrial Layers

The endometrium has two layers: the Functional layer sheds, Basal layer remains for the next cycle.

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Blastocyst Formation

The stage of development after the morula forms a fluid-filled cavity, marking the transition to implantation.

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Trophoblast

The outer cell mass of the blastocyst that contributes to the formation of the placenta.

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Implantation

The process in which the embryo attaches to the uterine wall, starting week 1 or 2 of pregnancy.

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Decidua

The modified endometrium that supports the implanted embryo during pregnancy.

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Advanced Maternal Age

Higher pregnancy risks for mothers aged 35 and older.

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Mitosis in PGCs

PGCs increase in numbers by mitosis and become dormant until puberty.

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Male Infertility

Inability to conceive due to low sperm count or motility.

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Infertility Causes in Women

Reasons for female infertility can include blocked tubes, ovulation issues, or sperm immunity.

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Menstrual Cycle Phases

The menstrual cycle consists of menstrual, proliferative, and secretory phases.

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Cycle Duration

The average menstrual cycle lasts about 28 days, but can vary by a week.

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Decidua Basalis

Part of the decidua that forms the maternal part of the placenta, located deep to the conceptus.

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Decidua Capsularis

The superficial part of the decidua that covers the conceptus.

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Decidua Parietalis

All remaining parts of the decidua; not directly involved with the embryo or placenta.

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Cytotrophoblast

The inner layer of the trophoblast, composed of mononucleated cells.

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Syncytiotrophoblast

The outer layer of the trophoblast, which is multinucleated and invades endometrial tissue.

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hCG

Human chorionic gonadotrophin; a hormone produced by the trophoblast that supports pregnancy.

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Chorion

The outermost fetal membrane that surrounds the embryo and amniotic cavity.

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Functional Layer

The apical 2/3 of the endometrium that sheds during menstruation.

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Blastocyst

The stage of development where the morula forms a fluid-filled cavity.

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Trophoblast Layers

The trophoblast differentiates into Cytotrophoblast and Syncytiotrophoblast during implantation.

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Primary Utero-Placental Circulation

The beginning of blood flow between the mother and embryo during pregnancy.

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Villi

Finger-like projections that enhance surface area for nutrient exchange in the placenta.

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Placenta

An organ formed by maternal and fetal tissues for nutrient and gas exchange.

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Cotyledons

Divisions within the placenta that separate maternal blood supply areas.

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Intervillous space

The area surrounding villi which contains maternal blood in the placenta.

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Fetal/Placental barrier

The barrier regulating exchange of nutrients and wastes between maternal and fetal blood.

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Gestational Trophoblastic Disease

A condition when an ovum loses its nucleus but gets fertilized by sperm, leading to abnormal growth.

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Amniotic Sac

A fluid-filled sac that surrounds and protects the embryo and foetus.

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Function of the Placenta

Connects the foetus to the uterine wall and facilitates nutrient and gas exchange.

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Allantois

A diverticulum that contributes to the formation of the umbilical cord and bladder development.

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Chorionic Villi

Finger-like projections from the chorion that increase surface area for nutrient exchange with maternal blood.

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Uteroplacental Circulation

Maternal blood flow that facilitates nutrient exchange with the foetus at the placenta.

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Formation of Primary Villi

The initial development stage of chorionic villi consisting of cytotrophoblast covered by syncytiotrophoblast.

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Functions of the Placenta

Includes nutrient uptake, waste elimination, hormone secretion, and protection against infection.

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Lacunar Stage

A phase where vacuoles appear in the Syncytiotrophoblast, forming intercommunicating lacunae for maternal blood.

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Study Notes

Gametogenesis, Implantation, Fetal Membranes and Placenta

  • Gametogenesis is a biological process where precursor cells divide and differentiate to create mature haploid gametes.
  • Gametes are produced in the gonads (ovaries in females, testes in males), containing haploid (half the normal, 23 in humans) chromosomes.
  • Male gametes are sperm (spermatozoa), and female gametes are ova (oocytes).
  • Spermatogenesis in males begins with spermatogonium, undergoes mitosis creating more spermatogonia, then creates primary spermatocytes (a diploid cell) which undergo meiosis I to create secondary spermatocytes (haploid cells). Secondary spermatocytes undergo meiosis II, to produce 4 spermatids that then mature to form sperm cells.
  • Oogenesis in females begins primoridal germ cells in the epiblast of the embryonic stage which migrate to the developing gonads in the developing abdominal cavity. Then, oogonia undergo mitosis and differentiate into primary oocytes, which then begin the first meiotic division, but stop at prophase I until puberty. At puberty, maturation begins, the primary oocyte completes meiosis I producing a secondary oocyte and a polar body. The secondary oocyte commences meiosis II, but arrests at metaphase II. If fertilization happens, meiosis II is completed and then the egg matures into an ovum.
  • The number of germ cells decrease during female development. Starting with 7 million germ cells in the 5th month of development, the number dwindles down to 700,000 at birth, and finally 400,000 at puberty.
  • The ovarian cycle involves the maturation and release of an ovum from the ovary.
  • The uterine/menstrual cycle is the cycle of changes occurring in the lining of the uterus (endometrium) that prepares it for pregnancy, with phases including menstrual, proliferative, and secretory phases.
  • Implantation occurs during week 1 & 2 after fertilization, with the blastocyst attaching to the uterine epithelium, and trophoblast differentiating into cytotrophoblast and syncytiotrophoblast layers.
  • The trophoblast differentiates later to form extraembryonic membranes and the placenta.
  • The placenta is an organ that connects the developing fetus to the uterine wall, supporting nutrient uptake, gas exchange, secretion of hormones (progesterone and oestrogen), thermo-regulation, waste elimination, protection from infection, and metabolism of substances, all from both fetal and maternal contributions.
  • After implantation, extra-embryonic membranes like the chorion, amnion and yolk sac grow and the developing placenta is established within the uterine wall by the end of the 3rd month, composed of a fetal part (chorion) developing from the trophoblast and maternal part (decidua basalis) developing from the endometrium, divided into sections called cotyledons.
  • Problems, including ectopic pregnancies, placental abruption, placenta previa, and hydatidiform moles (a type of gestational trophoblastic disease - GTD), can occur, posing potential issues.
  • Gestational trophoblastic disease (GTD) involves abnormal placental tissue growth and potential cancer development.
  • The umbilical cord connects the fetus to the placenta, carrying oxygenated blood and removing deoxygenated blood. It's formed from the allantois, yolk sac, and part of the chorion. This cord has 3 blood vessels: 2 arteries and one vein. The umbilical cord is embedded in a connective tissue called Wharton's jelly.
  • Fertilization occurs in the ampullary region of the uterine tube, involving the approximation and fusion of the male and female gametes. The steps include: approximation of gametes, contact & fusion of gametes, and detailed phases such as penetration of corona radiata, zona pellucida, and the fusion of the oocyte and sperm cell membranes, leading to zygote formation.

Chromosomal abnormalities

  • Aneuploidy refers to an abnormal number of chromosomes.
  • Nondisjunction is a meiotic error where chromosomes fail to separate correctly, primarily causing miscarriage.
  • Trisomy is the presence of three copies of a chromosome instead of the normal two (e.g., Down syndrome).
  • Examples of abnormalities include Down syndrome (Trisomy 21), and Turner syndrome (45, X).

Learning Outcomes

  • Students will be able to describe the process of gametogenesis in males and females.
  • Students will be able to describe the process of ovulation and pre-embryonic development, including implantation.
  • Students will be able to outline the main stages of endometrial development within the menstrual cycle.
  • Students will be able to discuss placental development and function.
  • Students will be able to describe how abnormalities, such as hydatidiform moles and ectopic pregnancies occur.

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Test your knowledge on chromosomal abnormalities, sexual reproduction, and the processes involved in gamete formation. This quiz covers important concepts such as trisomy, meiosis errors, and fertilization barriers. Perfect for students studying genetics and reproductive biology.

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