Reproductive System

Question 1

Bipotential structures

Answer 1

Bipotential gonads (cortex + medulla)

Internal genitalia accessory ducts:
- Wolffian ducts
- Müllerian ducts

External genitalia: genital tubercle, urethral folds, urethral groove and labioscrotal swelling

Question 2

Bipotential structure development in males vs females

Answer 2

Males:
Gonads: SRY → testis-determining SRY protein(s) → medulla → testes
- Sertoli cells → AMH
- Leydig cells → testosterone → DHT
Wolffian ducts + testosterone: epididymis, vas deferens and seminal vesicles
Müllerian w/ AMH regresses
External w/ DHT: Genital tubercle → glans penis, Urethral folds + grooves → shaft of penis, Labioscrotal swelling → shaft of penis and scrotum

Females:
Gonads cortex w/o SRY → ovaries
Wolffian ducts w/o testosterone regress
Müllerian w/o AMH → fallopian tubes, uterus, cervix and upper vagina
External w/o DHT: Genital tubercle → clitoris, Urethral folds + grooves → labia minora, opening of vagina and urethra, Labioscrotal swelling → labia majora

Question 3

Describe and compare male and female patterns of gametogenesis.

Answer 3

Male gametogenesis: only spermatogonia at birth
- meiosis does not begin until puberty

Oogonia (germ cells) completes mitosis by 5th months fetal development
Born with all primary oocytes in primordial follicles (4n)
- meiosis I begins is arrested until puberty
- meiosis I completes then into mid meiosis II occurs during preovulation

Question 3

Reproductive hormones to know

Roles

Answer 3

Testosterone (aromatase) → estradiol
Testosterone (5⍺-reductase) → dihydrotestosterone (DHT)

GnRH (hypothalamus) → FSH + LH (anterior pituitary release)
- GnRH 1-3 hour tonic pulsatile release regulated by Kisspeptin peptide
- FSH regulated by activins/inhibins and estrogen/progesterone

FSH regulates follicular growth or sperm numbers
LH regulates ovulation or testosterone production

Question 4

Secretory cells during gametogenesis

Answer 4

Sertoli cells + granulosa cells produce AMH and ABP (sertoli only)
- regulated by FSH + androgens/estrogens
- AMH prevents multiple follicles developing

Leydig + Theca cells produce androgens (convert to testosterone or estrogens)
- regulated by LH