Embryo Development of the Genital System Flashcards
(36 cards)
What layer gives rise to the kidney and gonad
Intermediate Mesoderm
Coelomic epithelium (somatic support cells or mesothelium)
- lines what structure?
- gives rise to what? and who do they do?
Lining from the somatic plate mesoderm lining the gonadal ridge.
gives rise to primary and secondary sex cords, eventually become the cortex and medulla of gonads.
Primordial germ cells
- came from what, when?
- where do they reside?
come from epiblast in week 2,
reside in allantois/ yolk sac endoderm
what does the paramesonephric duct give rise to?
female genitalia, superior part of the vagina
Primordial germ cells
- Male
- Female
- their supporting cells, where they come from, and what they do
in males
- Sertoli Cells- came from coelomic epithelium, they nurture/support gamete
- interstitial cells- come from intermediate mesoderm, produce androgens
in females
- follicle cells, came from coelomic epithelium, “follicular cells” support/nurture
- thecal cells from intermediate mesoderm, production of estrogen
When do gametes arise and why?
gametes arise during week two because you only want two germ layers not 3 like youd have in the third week.
Germ cells migrate through what during which week?
because we don’t want all the gametes to be exposed to the crazy amounts of signaling occuring during week 4
migrate through the primitive streak and reside in the yolk sac/allantois during the third week
What do the germ cells do in the fifth week? sixth week? gonad development?
migrate through the dorsal mesentery, colonize the sex cords of the gonadal ridge by sixth week
gonad development begins week 5
FYI
5th prenatal month about 6 million oocytes, by puberty around 40,000. 400 released throughout lifetime
Sex determination
- central event
- secondary events, gives us what
central event is differentiation of testes or ovaries, genetic
secondary events are production of humoral factors by gonads, gives us our phenotype
SRY gene
if you have it, youll be male. if you have XY but splice out SRY, youll be female.
SRY present with XY, functional leydig producing test, sertolis producing AMH, what do you get?
Sex determination XX with SRY absent
Int mesoderm cells become thecal cells instead of leydig, coelomic epithelial cells become follicular cells, which produce No AMH, so paramesonephric ducts persist=female internal genitalia.
Thecal cells don’t produce test, so mesonephric ducts degenerate and do not remodel into male internal genitalia.
estrogens present instead of DHT to make female external genitalia
FYI disorders of sexual development revised terminology
Ovotesticular DSD (true Gonadal Intersex)
most common genotype
characteristics?
phenotype?
ovotestis does not function.
46, XX DSD
- caused by exposure to what?
- characteristics of genitalia?
- what is main cause (disorder) wise?
46, XY DSD
- caused by what two things
- testicular development
- external genitalia?
Androgen insensitivity syndrome
- testes present, but normal appearing what?
- blind end?
- internal female genitalial?
- puberty changes? menstruation?
Sex Determination scenarios:
SRY Present:
- Not enough AMH: internal genitalia? external genitalia?
- 5a reductase deficiency: cant convert test to DHT: internal genitalia? external genitalia?
not enough amh would lead to both internal genitalia, external would be normal male
5a reductase deficiency with sry present would lead to internal male genitalia, and either female or ambiguous female external genitalia.
Indifferent stage of gonad development:
- which week?
- where does gonadal ridge appear
- what happens to primary sex cords?
- what happens to secondary sex cords?
Male gonad development: Testis
- what persists, and what does it become?
- connective tissue becomes?
primary sex cords are CE, connective tissue becomes leydig and tunica albuginea which is intermediate mesoderm
Female Gonad Development
- secondary sex cords become what, come from what?
- intermediate mesoderm becomes?
secondary sex cords are CE, thecal cells are IM
Indifferent stage: 2 ducts
-what are they, who do they degenerate in
Differentiation of male duct system:
- sertoli cells have what affect?
- Leydig cells have what affect?
structures that come from mesonephric duct vs mesonephric tubules
**remnants of paramesonephric duct in normal male: utriculus prostaticus, appendix testis, bottom right of picture**
