Embryo Development of the Genital System Flashcards
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**
Differentiation of Female Duct System
- paramesonephric ducts where are they at?
- cranial portion of duct becomes? caudal portion?
- uterovaginal primordium projects towards what? what does it produce?
epoophoron and paroophoron can be found in mesovarium,
urogenital sinus is the bladder
paramesonephric duct becomes uterine tube uterus and superior part of vagina
** gardner cysts are cysts of epoophoron and paroophoron remnants of mesonephric ducts**
Differentiation of Uterus and Vagina:
- Uterovaginal primordium is a fused what?
- what does the uterovaginal primordium contact and what does that make?
- The sinus tubercle induced formation of what?, what type of cells are these and where do they extend? fuse to form what?
- Vaginal plate eventually becomes?
Uterus, superior part of vagina, come from paramesonephric duct. inferior part comes from endoderm, specifically urogenital sinus
describe what went wrong in each figure
A. Paramesonephric ducts caudal portion did not fuse: each created a sinovaginal bulb so 2 vaginas, 2 uteri.
B. Partial failure of paraducts to fuse
C. Caudal portion of para duct fused but upper did not
D. Atrophy/atresia of one para duct
E. Atrophy of para duct at most caudal portion
F. Sinuvaginal bulbs did not form
Male urogenital Sinus:
Prostate: pelvic part comes from? smooth muscle/connective tissue comes from?
bulbourethral glands: phallic part comes from?
smooth muscle/cxn tissue comes from?
Male External Genitalial
- under influence of what?
- genital tubercle becomes?
- urogenital folds do what, forming what structures
- labioscrotal swellings
urogenital folds fuse and give rise to the lateral walls of the urethra as in the skin. the urethra itself is endoderm.
corpus cavernosum/spongiosum are mesoderm
Female external genitalia:
- under the influence of what?
- genital tubercle becomes?
- urethral folds become?
labioscrotal swellings become?
Spongy Urethral Completion
- UG folds
- Fossa?
need endoderm spongy urethra to meet up with ectoderm of glans penis.
Hypospadia is on what side?
- glanular hypospadia what happened
- penile hypospadia what happened?
- penoscrotal hypospadia what happened?
Ventral,
in a glanular hypospadia the navicular fossa didn’t migrate correctly
penile hypospadia urogenital folds didnt fuse (skin ecotoderm around the spongy urethra)
penoscrotal hypospadia: labial scrotal swellings didnt fuse properly.
Epispadias
- improper location of what?
- what side?
- most often associated with what bladder disorder
dorsal surface, ectopic vesicae/estrophy of the bladder.
genital tubercle grows in the posterior direction
Ligaments supporting female reproductive organs
Ovary
Uterus
Homologs
