Overview
The female reproductive system is more complex than the male system due to two interconnected hormonal cycles occurring monthly. Women are born with all eggs they will ever produce, embedded in structures called follicles that protect and nourish the eggs through maturation.
Puberty and Reproductive Timeline
- Puberty typically occurs between ages 12–14; physical changes (breast development, body hair, fat distribution) begin earlier
- Menarche: first menstrual cycle marks reproductive onset
- Menopause: end of reproductive capacity; women have ~40–50 year reproductive window
- Men can reproduce from puberty until death; women only during this window
- Post-menopause pregnancy requires medical intervention
External Anatomy (Vulva/Pudendum)
- Mons pubis: rounded, pubic hair–covered area above genitals
- Labia majora and minora: outer and inner lip structures
- Clitoris bulb: located at top of labia
- Vestibule: contains urethral and vaginal openings plus associated glands
- Anus: posterior boundary
Reproductive Glands
- Bartholin's (greater vestibular) glands: surround vaginal opening; secrete lubrication into vestibule and vaginal canal; clogged ducts can cause discomfort
- Skene's (paraurethral) glands: two on each side of urethral opening; secrete lubrication; swell to partially close urethra during intercourse to prevent urination
- Clitoris: textbook role is to swell during intercourse and apply pressure to penis head to encourage ejaculation; actual structure is large boomerang-shaped nerve network extending around urethral opening, vaginal canal, and anus
- Mammary glands: produce breast milk; regulated by prolactin and oxytocin; active during pregnancy and lactation
Internal Anatomy
- Ovaries: bilateral symmetric organs; women can reproduce with one ovary
- Uterus: sits atop bladder; connected to ovaries by Fallopian tubes
- Fallopian (uterine) tubes: draw ovulated egg from ovary toward uterus
- Posterior view orientation: large intestine visible behind reproductive organs
Mammary Glands and Lactation
- Hormone regulation: prolactin (production) and oxytocin (milk ejection)
- Breast tissue becomes active during pregnancy; milk production begins just before, during, or after childbirth
- Lactation challenges: underproduction common; child latching issues can halt milk production
- Baby's saliva during feeding communicates with mother's immune system to adjust breast milk composition
- Without proper latching, feedback system fails and milk production ceases
- Formula shortages pose serious risk for families unable to breastfeed
- Breast structure: arranged into alveoli (alveolar sacs); lactiferous ducts and sinuses transport milk to nipple; baby latches onto areola
Ovarian Anatomy
- Two regions: cortex (site of follicular changes) and medulla (blood vessels, nerves, lymphatics)
- Outer layers: germinal epithelium (mesothelium) and tunica albuginea
- Ovarian cortex houses all follicular development stages
- By menopause, ovaries covered in scar tissue from repeated ovulation wounds
Ovarian Cycle
The 28-day ovarian cycle consists of three phases controlled by brain hormones (GnRH, FSH, LH) and regulates the uterine cycle through estrogen and progesterone.
| Phase | Duration | Dominant Hormone | Key Events |
|---|
| Follicular Phase | Days 1–13 | FSH | GnRH triggers FSH release; dozens of follicles begin maturation; low estrogen secreted |
| Ovulation | Day 14 | LH | LH surge causes estrogen spike; most mature (Graafian) follicle migrates to cortex edge; egg ruptures out creating wound (corpus hemorrhagicum); inhibin secreted to shut off FSH/LH |
| Luteal Phase | Days 15–28 | Progesterone, Estrogen | Corpus hemorrhagicum → corpus luteum (glandular mass producing progesterone/estrogen); if no pregnancy, becomes corpus albicans (scar tissue); low hormone levels trigger new cycle |
- Pregnancy maintains luteal phase for full gestation (~9 months)
- Eggs halted in prophase I of meiosis until puberty; resume maturation monthly thereafter
Follicular Development and Histology
- Primordial follicles: tiny structures present at birth; contain primary oocytes (cannot be fertilized)
- Primary follicles: first maturation stage under FSH influence
- Secondary follicles: antrum (fluid-filled space) begins forming; follicular fluid provides nutrients
- Mature (Graafian/tertiary) follicles: large structure at cortex edge ready for ovulation; contains secondary oocyte (can be fertilized)
- Ovulation: egg ruptures out with corona radiata (crown of cells providing nutrition) and zona pellucida (protective white layer); both protect egg and must be penetrated by sperm for fertilization
- Post-ovulation structures: corpus hemorrhagicum (wound) → corpus luteum (hormone-secreting glandular mass) → corpus albicans (scar tissue)
Follicular Structure Components
- Theca: cuboidal cells lining follicle exterior (eggshell)
- Granulosa cells: cells surrounding antrum and supporting oocyte
- Antrum: fluid-filled space in secondary and mature follicles
- Corona radiata: radiating crown of cells around oocyte; pulls nutrients from follicular fluid
- Zona pellucida: protective layer directly surrounding oocyte