Female Reproductive System Physiology - MCQ Revision Summary

1. Ovarian Anatomy

• Ovary = two functions: oogenesis + secretion of estrogen & progesterone
• Three zones: Cortex (outer, contains follicles/oocytes) → Medulla (middle, mixed cells) → Hilum (inner, vessels/lymphatics)
• Functional unit = ovarian follicle (one oocyte + surrounding endocrine cells)

2. Oogenesis - Key Numbers (High-Yield MCQ)

• Oogonia form by mitosis until ~gestational weeks 20-24, then enter meiosis
• Oocytes arrested in prophase I from ~6 months after birth until ovulation
• At ovulation → meiosis I is completed → secondary oocyte enters fallopian tube
• Meiosis II is completed only if fertilization occurs → forms haploid ovum (23 chromosomes) + 2nd polar body
• Females do NOT produce new oogonia after birth (unlike males who continuously produce spermatogonia)

3. Follicular Development - 3 Stages

• Parallels prophase of oocyte - lasts ~13-50 years
• Granulosa cells proliferate, theca interna develops
• No follicle passes this stage in prepubertal ovaries

• Takes 70-85 days; only during reproductive years
• Antrum forms (contains estrogens, FSH, mucopolysaccharides, proteins)
• Graafian follicle = 2-5 mm diameter

• Occurs 5-7 days after menses
• One dominant follicle grows to 20 mm within 48 hours
• Cohort follicles undergo atresia (via apoptosis)
• Dominant follicle selected based on its ability to secrete estrogen
• Ovulation occurs on day 14 of a 28-day cycle

4. Corpus Luteum

• Formed from residual ruptured follicle after ovulation (granulosa + theca cells + capillaries + fibroblasts)
• Secretes estrogen + progesterone
• Growth requires VEGF (vascular endothelial growth factor)
• If no fertilization: corpus luteum regresses → corpus albicans (after ~14 days)
• If fertilization occurs: corpus luteum is maintained by hCG from trophoblast; persists until placenta takes over steroid synthesis (at ~8-10 weeks)
• Minor bleeding at ovulation → peritoneal irritation = "Mittelschmerz" (mid-cycle pain)

5. Hormonal Control - Two-Cell Theory

• Theca interna cells: stimulated by LH → synthesize androgens (androstenedione, testosterone)
• Granulosa cells: stimulated by FSH → aromatize androgens to estrogen (estradiol)
• This is the "two-cell, two-gonadotropin" model

Gonadotropin Feedback

• LH surge (mid-cycle): triggers final maturation and ovulation ~36-48 hours later
• FSH surge (smaller, concurrent with LH): facilitates follicle rupture
• Progesterone also inhibits LH during the luteal phase

6. The Menstrual Cycle (28-Day Model)

Phase Overview

• Luteal phase is always 14 days (fixed); follicular phase length varies → total cycle length varies
• Menstruation = shedding of stratum functionale (supplied by spiral arteries)
• Stratum basale is NOT shed (supplied by straight basilar arteries); regenerates endometrium
• Prostaglandin PGF2α causes spiral artery vasospasm → ischemia → menstrual flow
• NSAIDs reduce menstrual cramping by inhibiting prostaglandin synthesis

7. Cervical Mucus Changes

• Spinnbarkeit = stretchiness of cervical mucus, maximal at ovulation

8. Actions of Estrogen

• Uterus: endometrial proliferation, spiral artery elongation, myometrial growth
• Cervix: watery, elastic mucus; ferning
• Fallopian tubes: stimulates motility (aids egg transport)
• Vagina: cornification of epithelium (cells become squamous, superficial)
• Breasts: ductal growth, areola enlargement, adipose deposition (breast shape)
• Bone: promotes pubertal growth spurt; then closes epiphyses (ends growth)
• Metabolic: subcutaneous fat deposition (female fat distribution); HDL↑, LDL↓
• Pituitary: prolactin secretion stimulated
• Feedback: negative (low levels) or positive (high sustained levels → LH surge)

9. Actions of Progesterone

• Uterus: converts proliferative → secretory endometrium (tortuous glands, glycogen, edema); raises threshold for uterine contractions (preserves pregnancy)
• Cervix: thick, scant, non-elastic mucus; blocks sperm
• Breasts: stimulates secretory activity in mammary ducts (collaborates with estrogen)
• Temperature: mild thermogenic effect → raises basal body temperature in luteal phase (~0.5°C) - basis of rhythm method
• Feedback: negative feedback on LH during luteal phase
• Pregnancy: maintains endometrial lining; prevents premature uterine contractions

10. Puberty in Females

• Triggered by pulsatile GnRH secretion from the hypothalamus (increased amplitude and frequency)
• GnRH → FSH + LH from anterior pituitary → ovarian estrogen production
• Sequence (mnemonic: THELARCHE before PUBARCHE before MENARCHE):
  1. Thelarche - breast development (first sign, ~8-13 years)
  2. Pubarche - pubic/axillary hair (adrenal androgens = adrenarche)
  3. Growth spurt (estrogen-driven)
  4. Menarche - first menstrual period (average ~12-13 years in developed countries)
• Estrogen causes the growth spurt and then closes epiphyses (ends growth)
• Adrenarche (adrenal androgen surge) precedes gonadarche and causes pubic/axillary hair

11. Menopause

• Defined as cessation of menses for 12 consecutive months (average age ~51)
• Cause: depletion of ovarian follicles → ovaries become unresponsive to FSH/LH
• Hormone profile:
  • Estrogen ↓↓, Progesterone ↓↓
  • FSH ↑↑ (markedly elevated - most sensitive marker), LH ↑
  • GnRH ↑ (loss of negative feedback)
• FSH > 40 mIU/mL = diagnostic of menopause
• Symptoms: hot flashes, vaginal atrophy, dyspareunia, osteoporosis, cardiovascular risk ↑, mood changes

12. Pregnancy Hormones (Overview)

13. Key High-Yield MCQ Facts

• Dominant ovarian hormone of follicular phase: Estrogen (17β-estradiol)
• Dominant hormone of luteal phase: Progesterone
• Trigger for ovulation: LH surge (caused by high sustained estrogen = positive feedback)
• Ferning of cervical mucus: Estrogen effect (follicular phase)
• Basal body temperature rise: Progesterone effect (luteal phase)
• First sign of female puberty: Thelarche (breast bud)
• Marker of menopause: FSH elevation (>40 mIU/mL)
• Meiosis I completed: At ovulation
• Meiosis II completed: Only if fertilization occurs
• hCG function: Rescues corpus luteum from regression
• Two-cell theory: LH acts on theca → androgens; FSH acts on granulosa → aromatization to estrogen
• Stratum functionale: Shed during menstruation; supplied by spiral arteries
• Stratum basale: NOT shed; regenerates endometrium; supplied by basilar arteries
• Luteal phase duration: Always 14 days (fixed)
• Mittelschmerz: Mid-cycle pain from follicular rupture at ovulation

1. Oogenesis - meiosis timeline, arrest stages, key oocyte count numbers
2. Female Hormonal System - GnRH → FSH/LH → ovarian hormones; two-cell two-gonadotropin theory; three estrogens and their relative potencies; inhibin/activin/relaxin
3. Monthly Ovarian Cycle - gonadotropin patterns, LH surge mechanism, feedback oscillation (3-step)
4. Endometrial Cycle - proliferative/secretory/menstrual phases; stratum functionale vs basale; cervical mucus changes; PGF2α role
5. Estrogen Actions - reproductive tract, breast, skeleton, metabolism
6. Progesterone Actions - uterus, cervix, breast, thermogenic (BBT)
7. Puberty & Menarche - KNDy/kisspeptin mechanism, sequence of events, age norms
8. Menopause - hormone changes (FSH markedly elevated), clinical features, HRT
9. Female Fertility & Contraception - fertile window, rhythm method, OCP mechanism and failure rates
10. High-yield MCQ Quick Reference Table - 48 Q&A pairs covering all classic exam points