Lecture 01: Sex Determination (Pozor) Flashcards
3 stages of sexual differentiation
1) chromosomal (XX or XY)
2) gonadal (ovary or testis)
3) phenotypic (male or female)
each stage depends on the previous one
what does chromosomal sex drvie?
gonadal differentiation
Main precursor to gonads
genital ridge
Mesonephros develops into what structures?
small structures near but not IN the gonads
Where is genital ridge located?
next to mesonephros and mesonephric ducts
yolk sac
first fetal membrane that provides nutrition to developing embryo. Where Primordial germ cells are located before they migrate to genital ridge to become gametes
gametes
spermatozoa and oocytes
precursor to gametes
primordial germ cells (PGCs)
migration of PGCs (start & end)
start –> yolk sac
end –> genital ridge, where they colonize
What initiates testis differentiation?
Sry (sex determining region) gene on Y chromosome (TDF - Testis determining factor)
T or F: ovarian differentiation is a default process
FALSE! Needs 2 copies of key genes from 2 X chromosomes to occur
precursor to female sexual organs
Paramesonephric duct (Mullerian duct)
precursor to male sex organs
Mesonephric duct (Wolffian duct)
Influence of testicular hormones
presence or absence influences development of tubular tract
Precursor to epididymis
mesonephric duct
What hormone do leydig cells produce?
Testosterone
What hormone do sertoli cells produce?
Anti-Mullerian Hormone (AMH) (causes regression of the mullerian duct system and induction of wolffian duct system) *****
lack of AMH –>
maintenance of female tract
3 components of wolffian duct system
epididymis, deferent duct, urethra
4 components of mullerian duct system
oviducts, uterus, cervix, crania vagina
precursor to cranial vestibule
urogenital sinus
what hormones cause physical masculinization? (2)
testosterone and DHT
Absense of testosterone/DHT –>
female physical differentiation
Most common cause of chromosonal disorder of sex. differentiation
non-disjunction of sex chromosomes or chromatids **