Anatomy and Physiology of Female Genitalia and Reproduction

🌸 Anatomy and Physiology of Female Genitalia and Reproduction (In Depth)

The female reproductive system is specialised for gamete production, fertilisation, pregnancy, childbirth, and lactation. It is hormonally regulated and undergoes cyclical changes that prepare the body for potential conception each month. Understanding its anatomy and physiology is essential for managing fertility, pregnancy, endocrine disorders, and gynaecological disease.

📍 1) Internal Reproductive Organs

🥚 Ovaries

• Paired, almond-shaped organs in the ovarian fossae of the pelvis.
• Functions:
  • Production of ova (oocytes).
  • Secretion of oestrogen, progesterone, inhibin, and androgens.
• Structure:
  • Cortex: Contains follicles at different stages.
  • Medulla: Blood vessels, nerves, lymphatics.

🧬 Fallopian Tubes (Uterine Tubes)

• ~10 cm long, extending from ovaries to uterus.
• Four parts:
  • Infundibulum (fimbriae)
  • Ampulla (site of fertilisation)
  • Isthmus
  • Intramural part
• Ciliated epithelium propels ovum toward uterus.

🏛️ Uterus

• Pear-shaped muscular organ in pelvis.
• Functions: implantation, fetal development, labour.
• Layers:
  • Endometrium: Cyclically responsive lining.
  • Myometrium: Thick smooth muscle.
  • Perimetrium: Serosal covering.
• Parts: fundus, body, isthmus, cervix.

🚪 Cervix

• Lower uterine segment opening into vagina.
• Produces cervical mucus:
  • Thin at ovulation → sperm passage.
  • Thick in luteal phase → barrier.
• Dilates during labour.

🛤️ Vagina

• Fibromuscular canal (8–10 cm).
• Functions: intercourse, childbirth, menstrual flow.
• Acidic environment (lactobacilli) protects from infection.

📍 2) External Genitalia (Vulva)

• Labia majora: Hair-bearing protective folds.
• Labia minora: Inner folds forming vestibule.
• Clitoris: Erectile tissue, rich innervation.
• Vestibule: Openings of urethra and vagina.
• Bartholin glands: Lubrication.

🩸 3) Blood Supply, Innervation, and Lymphatics

• Arteries:
  • Ovarian arteries (abdominal aorta)
  • Uterine arteries (internal iliac)
• Veins: Ovarian and uterine plexuses → IVC.
• Innervation: Autonomic pelvic plexus + pudendal nerve.
• Lymphatics:
  • Ovary → para-aortic
  • Uterus → iliac
  • Vulva → inguinal

⚙️ 4) Physiology: Ovarian Cycle

The ovarian cycle governs egg maturation and hormone secretion. It is controlled by the hypothalamic–pituitary–ovarian axis.

🌱 Follicular Phase (Days 1–14)

• GnRH → FSH + LH release.
• FSH stimulates follicle growth.
• Dominant follicle secretes oestrogen.
• Oestrogen → endometrial proliferation.

🔥 Ovulation (Mid-cycle)

• High oestrogen → positive feedback.
• LH surge → follicle rupture.
• Oocyte released into tube.

🌙 Luteal Phase (Days 15–28)

• Corpus luteum forms.
• Secretes progesterone.
• Maintains endometrium.
• Regression if no pregnancy.

🧠 5) Physiology: Uterine (Menstrual) Cycle

🩸 Menstrual Phase

• Shedding of endometrium.
• Low oestrogen and progesterone.

🌼 Proliferative Phase

• Oestrogen-driven regeneration.
• Endometrial thickening.

🌕 Secretory Phase

• Progesterone-dominant.
• Glands secrete nutrients.
• Prepares for implantation.

🤰 6) Fertilisation and Pregnancy

• Fertilisation occurs in ampulla.
• Zygote → blastocyst → implantation (day 6–7).
• Trophoblast produces hCG.
• hCG maintains corpus luteum.
• Placenta later produces hormones.

Key pregnancy hormones: progesterone, oestrogen, hCG, hPL, relaxin.

🍼 7) Lactation Physiology

• Prolactin: Milk production.
• Oxytocin: Milk ejection reflex.
• Suckling → hypothalamic reflex.

⚠️ 8) Clinical Relevance

🎗️ Common Disorders

• PCOS: Anovulation, hyperandrogenism.
• Endometriosis: Ectopic endometrium.
• Fibroids: Benign myometrial tumours.
• Infertility: Tubal, ovulatory, uterine causes.
• Cervical cancer: HPV-related.
• Ovarian cancer: Often late presentation.

🩺 Screening and Prevention

• Cervical screening (HPV testing).
• Breast screening.
• HPV vaccination.

📊 Quick Revision Table

📝 Summary

The female reproductive system integrates anatomical specialisation with cyclical hormonal regulation to enable ovulation, fertilisation, implantation, pregnancy, and lactation. The ovaries generate gametes and sex hormones, while the uterus and tubes provide the environment for early development. Disruption at any level — endocrine, structural, or immunological — can impair fertility and reproductive health.

💡 Teaching Tip: Think in three layers: Ovary = hormone engine, Tube = fertilisation highway, Uterus = developmental incubator. If one fails, reproduction fails.