Week 8 · Lecture Slides · Reproductive

Reproductive Systems.

Seven slides on male and female reproductive anatomy, gametogenesis, and the menstrual cycle. Sketch each system + the cycle from memory.

Practice these cards

Core concept

Reproductive Systems

What you'll do

  • Move through six concept slides
  • Three slides have a drawable canvas
  • Toolbar: pen color, size, eraser, undo, add image, save
  • Drop in your own anatomy images to label them
Male + Female

Male

Testes (sperm + testosterone)
Ducts (epididymis, vas, urethra)
Glands (prostate, seminal, bulbourethral)
Penis

Female

Ovaries (eggs + hormones)
Fallopian tubes
Uterus + cervix
Vagina + vulva

Male

Male Reproductive Anatomy

Sperm + delivery

  • Testes: produce sperm (spermatogenesis) + testosterone (Leydig cells)
  • Seminiferous tubules with Sertoli cells (nurse, blood-testis barrier)
  • Epididymis: sperm matures, gains motility
  • Vas deferens: conducts sperm
  • Glands: seminal vesicles (60% of semen, fructose), prostate (30%, alkaline), bulbourethral (lubricant)
  • Penis: erectile tissue (corpora cavernosa + spongiosum)
  • Scrotum: external for cooler temp (~2°C below core)
Takeaway: cooler temp is critical for spermatogenesis. Cryptorchidism (undescended testis) → impaired fertility + ↑ cancer risk if not corrected. Tight underwear, hot tubs reduce sperm count.

Spermatogenesis

Spermatogenesis

Diploid → haploid sperm

  • Spermatogonia (2n) stem cells line tubules
  • Mitosis makes primary spermatocytes (2n)
  • Meiosis I → secondary spermatocytes (1n)
  • Meiosis II → spermatids (1n)
  • Spermiogenesis: spermatids mature to spermatozoa (head + midpiece + tail)
  • ~72 days total to produce a mature sperm
  • ~300 million sperm per ejaculate, lifelong production
Draw: a cross-section of a seminiferous tubule. Show progression from outside (spermatogonia) toward lumen (spermatids → sperm). Add Sertoli cells extending from basement membrane to lumen. Mark each developmental stage.

Female

Female Reproductive Anatomy

Gametes + gestation

  • Ovaries: oogenesis + estrogen + progesterone
  • Fallopian (uterine) tubes: capture egg, site of fertilization
  • Uterus: implantation + gestation (fundus, body, cervix)
  • Endometrium: functional + basal layers; sheds monthly
  • Myometrium: smooth muscle; contracts in labor
  • Vagina: birth canal + receives sperm
  • External (vulva): labia majora/minora, clitoris
  • Mammary glands: milk production (post-partum)
Takeaway: cervix is the gatekeeper. Mucus thins midcycle (sperm-friendly) and thickens during pregnancy + on progestins (blocks sperm). Cervical cancer screening (Pap) is one of the most successful screening programs ever.

Oogenesis

Oogenesis & Follicle Development

Different from male

  • Oogonia → primary oocytes formed before birth (~2 million)
  • Arrested in prophase I until puberty
  • At ovulation: completes meiosis I → secondary oocyte (1n) + polar body
  • Meiosis II only completes if fertilized
  • Folliculogenesis: primordial → primary → secondary → Graafian (mature) → corpus luteum after ovulation
  • ~400 ovulated in a lifetime
  • Finite supply, declines with age (menopause when depleted)
Draw: an ovary showing the stages of follicle development around its edge. Start with primordial follicle, then primary, secondary, mature Graafian, then ovulation, then corpus luteum. Use a clockwise progression.

Cycle

Menstrual Cycle

~28 days, two phases

  • Ovarian cycle:
  • Follicular (days 1-14): FSH drives follicle growth, estrogen rises
  • Ovulation (day 14): LH surge
  • Luteal (days 14-28): corpus luteum makes progesterone (+ some estrogen)
  • Endometrial cycle:
  • Menstrual (days 1-5): shedding
  • Proliferative (5-14): estrogen rebuilds endometrium
  • Secretory (14-28): progesterone preps for implantation
  • No pregnancy → corpus luteum dies → progesterone drops → menstruation
Takeaway: cycle is regulated by GnRH (hypothalamus) → FSH/LH (pituitary) → ovary → estrogen + progesterone. Hormonal birth control disrupts this feedback to prevent ovulation.

Clinical

Reproductive Disorders

Common hits

  • BPH: benign prostatic hyperplasia, urinary obstruction
  • Prostate cancer: most common male cancer
  • Erectile dysfunction: vascular, neurologic, or psychogenic
  • PCOS: polycystic ovary syndrome, anovulation + androgen excess
  • Endometriosis: endometrial tissue outside uterus, pain + infertility
  • Fibroids: benign uterine smooth muscle tumors
  • Menopause: ~age 51, ovarian function ends
  • STIs: chlamydia, gonorrhea, HPV, HIV, syphilis
Takeaway: reproductive endocrinology is full of feedback loops. PCOS, infertility, irregular cycles, hirsutism, and menstrual disorders all map back to the hypothalamic-pituitary-gonadal axis or ovarian function.