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Questions and Answers
What primarily occurs during the menstrual phase of the uterine cycle?
What primarily occurs during the menstrual phase of the uterine cycle?
What is the primary hormone responsible for the changes in cervical mucus during the proliferative phase?
What is the primary hormone responsible for the changes in cervical mucus during the proliferative phase?
What happens to the endometrium during the secretory phase?
What happens to the endometrium during the secretory phase?
How does the thickness of the endometrium change during the proliferative phase?
How does the thickness of the endometrium change during the proliferative phase?
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What role does luteinizing hormone (LH) play at the end of the proliferative phase?
What role does luteinizing hormone (LH) play at the end of the proliferative phase?
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What is the condition of ovarian hormones at the beginning of the menstrual phase?
What is the condition of ovarian hormones at the beginning of the menstrual phase?
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Which layer of the uterus is primarily affected during the menstrual phase?
Which layer of the uterus is primarily affected during the menstrual phase?
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What changes occur to the spiral arteries during the secretory phase?
What changes occur to the spiral arteries during the secretory phase?
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What hormonal change causes the cervical mucus to become viscous, forming a cervical plug?
What hormonal change causes the cervical mucus to become viscous, forming a cervical plug?
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What happens to the endometrium if fertilization does not occur?
What happens to the endometrium if fertilization does not occur?
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During which phase does ischemia occur due to the constriction of spiral arteries?
During which phase does ischemia occur due to the constriction of spiral arteries?
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Which phase corresponds with the ovarian luteal phase?
Which phase corresponds with the ovarian luteal phase?
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What is the consequence for women who undergo artificial induction of ovulation?
What is the consequence for women who undergo artificial induction of ovulation?
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What characterizes the functional layer of the endometrium during the secretory phase?
What characterizes the functional layer of the endometrium during the secretory phase?
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What occurs on the first day of menstrual flow?
What occurs on the first day of menstrual flow?
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Which layer of the uterus is directly involved in the menstrual cycle changes?
Which layer of the uterus is directly involved in the menstrual cycle changes?
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What is the primary function of the endometrium during the menstrual cycle?
What is the primary function of the endometrium during the menstrual cycle?
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During which phase of the menstrual cycle does the endometrium thicken in preparation for a possible pregnancy?
During which phase of the menstrual cycle does the endometrium thicken in preparation for a possible pregnancy?
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What changes occur in the uterine cycle when estrogen levels are high?
What changes occur in the uterine cycle when estrogen levels are high?
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What role does luteinizing hormone (LH) play in the menstrual cycle?
What role does luteinizing hormone (LH) play in the menstrual cycle?
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What occurs in the ovaries during menopause?
What occurs in the ovaries during menopause?
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What hormone is primarily responsible for the development of ovarian follicles?
What hormone is primarily responsible for the development of ovarian follicles?
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Which uterine layer is mainly involved in the changes during the menstrual cycle?
Which uterine layer is mainly involved in the changes during the menstrual cycle?
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What happens to the corpus luteum if fertilization does not occur?
What happens to the corpus luteum if fertilization does not occur?
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Study Notes
Introduction to Human Embryology
- Embryology is the study of prenatal development, starting with gametogenesis and ending with full-term infant formation.
- Embryology literally means the study of embryos, but generally refers to prenatal development of embryos and fetuses.
- It encompasses all developmental events during the prenatal period.
General Embryology
- Embryology studies prenatal development, starting with gametogenesis (formation of gametes) and ending with the formation of a full-term infant.
Prenatal Period
- The prenatal period is divided into three phases:
- Pre-embryonic period: From fertilization to implantation of the blastocyst. Ends with the formation of a flattened disc shaped mass of cells and germ layers.
- Embryonic period (3rd - 8th weeks): All major organ systems develop.
- Fetal period (weeks 9-38 or birth): Organs grow and complexity increases.
Postnatal Period
- Neonatal (Birth - 28 days)
- Infancy (neonate - 1st year)
- Childhood (13 months - 12 years)
- Adolescence (11-19 years)
- Puberty (12-15, 13-16 years)
- Adulthood (18-21 years)
Embryologic Terminology
- Oocyte: Female germ cell produced by the ovaries.
- Sperm: Male germ cell produced by the testes.
- Zygote: Cell resulting from the union of an oocyte and a sperm during fertilization (beginning of a new human being).
- Cleavage: Series of mitotic cell divisions of the zygote, forming blastomeres.
- Morula: Solid mass (12-32 blastomeres) formed by cleavage of a zygote.
- Implantation: Blastocyst attaches to the endometrium.
- Embryo: Developing human during early stages (3rd-8th week).
- Gastrula: Transformation of a blastocyst into a three-layered embryonic disc (third week).
- Neurula: Early embryo where the neural tube develops from the neural plate (3rd & 4th weeks).
- Conceptus: Entire products of conception (embryo and its membranes) from fertilization onwards.
- Fetus: Developing human from 9th week to birth.
- Primordium: First discernible indication of an organ.
- Trimester: A period of three calendar months.
- Fertilization age: The age of the embryo from the first day of the last normal menstrual period (2 weeks longer than fertilization age).
- Abortion: Expulsion of the embryo or fetus from the uterus before it is viable.
Male Reproductive System
- Components include:
- Primary sex organ: Testes
- System of ducts: Epididymis, ductus deferens, ejaculatory duct, urethra
- Accessory sex glands: Prostate, seminal vesicles, bulbourethral glands
Male Reproductive Structure: Testes
- The male sex gland.
- Located in the scrotum.
- Enclosed by the tunica vaginalis.
- Divided into 250 lobules containing seminiferous tubules. -Produce sperm. -Interstitial cells produce testosterone.
Seminiferous Tubules
- Contain two types of cells:
- Spermatogonia (stem cells)
- Sertoli cells (supporting cells)
Intratesticular Genital Ducts
- Straight tubules (tubuli recti)
- Rete testis
- Efferent ductules
Epididymis
- Coiled tube for sperm storage and maturation.
- Adds two layers around the sperm (glycoprotein coat, seminal protein coat).
Ductus/Vas Deferens
- Muscular tube that conveys mature sperm from the epididymis to the ejaculatory duct
- Ejaculatory duct: Union of ampulla of ductus deferens and ducts of seminal vesicles.
Accessory Male Reproductive Glands
- Seminal vesicles: Makes 60% of seminal fluid (contains fructose, prostaglandins, enzymes, other proteins).
- Prostate gland: Secretes 30% of seminal fluid (contains citrate, fibrinolysin).
- Cowper's glands (bulbourethral glands): Secretes an alkaline fluid neutralizing acidity of the urethra.
Female Reproductive System
- The female sex organs include ovaries, fallopian tubes, uterus, vagina, and external genitalia.
- Primary sex organ: Ovary
- Fallopian tubes (oviducts)
- Uterus
- Vagina
- External Genitalia
Uterus
- Hollow, muscular organ where the fertilized ovum is embedded, grows and nourished until birth.
- Part of the birth canal created by the cavity of the uterus and the vagina.
- Thick, muscular, and larger in multiparous women.
- Shaped like an inverted pear.
- Divided into three parts
- Fundus
- Body
- Cervix
- The three parts of the wall are perimetrium, myometrium, and endometrium
Uterine Tubes (Fallopian Tubes/Oviducts)
- Transport oocytes from the ovaries to the uterus and spermatozoa in the opposite direction.
- Fertilization and early cleavage occur here.
- About 10-12 cm long, extending from the uterus to the ends of the ovaries.
- Lined with secretory epithelium for nourishment of the ovum.
Ovaries
- Female sex gland.
- Located in the ovarian fosse on the lateral pelvic wall.
- Produce ova (eggs).
- Manufacture two hormones:
- Estrogen: Responsible for the development of secondary female sex characteristics.
- Progesterone: Responsible for the maintenance of pregnancy and increase the thickness and vascularity of the uterine endometrium.
Ovarian Cycle
- The monthly sequence associated with egg maturation.
- Two consecutive phases:
- Follicular phase (days 1-14): Follicle growth.
- Luteal phase (days 14-28): Corpus luteum activity.
- Follicle Development
- Primordial follicie
- Primary follicle
- Secondary follicle
- Antral follicle
- Mature or Graffian follicle
Ovulation
- Secondary oocyte is expelled from the ovary.
- Usually occurs mid-cycle (around day 14 of a typical 28-day cycle).
- The oocyte is caught by the fimbriae of the uterine tube.
Corpus Luteum
- Temporary endocrine gland that forms after ovulation.
- Secretes progesterone and some estrogen.
- Fate depends on pregnancy:
- If no pregnancy, degenerates into corpus albicans.
- If pregnancy, corpus luteum persists to maintain the uterine mucosa and then the placenta takes over.
The Uterine (Menstrual) Cycle
- Monthly changes in the internal layer of the uterus (endometrium).
- Three stages:
- Menstrual phase (days 1-5): Endometrial lining is shed.
- Proliferative/follicular phase (days 6-14): Endometrium rebuilds under estrogen influence.
- Secretory/luteal phase (days 15-28): Endometrium prepares for implantation, influenced by progesterone.
Anovulatory Menstruation & Artificial Induction of Ovulation
- Some women do not ovulate due to low gonadotropin concentrations.
- Medications can be used to stimulate gonadotropin release and induce ovulation.
- Multiple ovulation increases the risk of multiple pregnancies.
Gametogenesis
- The process of forming gametes (ova and spermatozoa)
- Oogenesis: Production of ovum.
- Spermatogenesis: Production of spermatozoa.
Mitosis
- Process where one cell divides to form two genetically identical daughter cells.
- DNA replication occurs before mitosis.
- Four main phases: prophase, metaphase, anaphase, and telophase.
Meiosis
- Cell division that reduces chromosome number from diploid to haploid.
- Two rounds of division (meiosis I and meiosis II).
- Only one round of DNA replication.
- Meiosis I and meiosis II steps are similar to mitosis, but the separation of homologous chromosomes and sister chromatids are specific.
Spermiogenesis
- Sequence of events where spermatids are transformed into mature sperms.
- Involves 4 phases:
- Golgi.
- Acrosomal.
- Maturation.
Comparison of Female & Male Gametes
- Oocytes are large, less mobile, abundant cytoplasm, have 22 autosomes + X chromosome.
- Sperm are microscopic, mobile, very little cytoplasm, have 22 autosomes + X or Y chromosome.
Sperm Transport
- Stored in the epididymis.
- Transported to the urethra by contractions of the ductus deferens.
- Secretions from accessory glands (seminal vesicles, prostate, bulbourethral glands) are added to the fluid.
- Travel from vagina through cervix and uterus, with sperms able to reach the fertilization site in a span of 5-45 minutes.
Applied Numerical Abnormalities of Sperms
- Azo spermia (Aspermia): No sperms.
- Oligospermia: Few sperms.
- Necrospermia: Dead sperms.
Male Infertility
- Low sperm count
- Poor sperm motility
- Abnormal sperm
- Medications/drugs
- Endocrine disorders
- Exposure to environmental pollutants
- Cigarette smoking
- Obstruction of a genital duct
Oocyte Transport
- Secondary oocyte is expelled from the ovary during ovulation with the follicular fluid.
- Fimbriae of the uterine tubes "sweep" the oocyte into the infundibulum and then into the ampulla of the uterine tube.
- Oocyte moves to the uterus via peristalsis (contractions).
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Description
This quiz explores the various phases of the menstrual cycle, including the menstrual, proliferative, and secretory phases. It addresses hormonal changes, the condition of the endometrium, cervical mucus, and the role of specific hormones. Test your understanding of female reproductive physiology.
