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Flashcards in Embryology* Deck (19)
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which germ cell layer gives rise to the urogenital system



how do the primordial germ cells get to the genital ridge

use the gut tube and its mesentery as a guide


what do the primordial cells join to at the genital ridge

proliferating body epithelium which becomes primitive sex cords


in males what happens to the primitive sex cords

continue to develop and organise themselves into horse shoe shaped structures
towards the hilum they break off into thinner structures for releasing sperm
germ cells form the semi tubules which do not fully develop until puberty when they form a lumen


what happens to the primitive sex cords in females

they break apart
individual primitive germ cells get surrounded by somatic support cells and form follicles that are initially deep in the ovary and move out into the cortex


in mesonephric duct how does the epididymis form

the area close to the duct the tubules become highly coiled to form the epididymis


what happens to the paragenital tubules in males

they begin to degenerate - can occasionally get some remnants


what happens to the paramesonpehric duct in males

degenerates but can get remnant - urticulus prostaticus


how do the seminal vesicles develop in males

as an out spreading of the mesonephric duct


what pulls the testis down into the scrotum
and how
does it degenerate

the gubernaculum which is a ligamentous structure that runs form the tests into the inguinal ring and then goes down to the scrotum

it shortness as development goes on and at the third month pulls the testis down into the deep inguinal ring where it stays till month 7
during that time an extension of the peritoneum forms the process vaginalis

the second shortening of the gubernaculum pulls the testis down into the scrotum and then the vaginalis loses its connection with the peritoneal cavity forming the tunica vaginalis

remnants of the gubernaculum stay in place as it helps anchor the testis to the floor of the scrotum - without this can get rotation of the testis


descent of the testis - which layers does it cross and which layers get attaches

transverse fascia -> internal spermatic fascia
transverse abdnominus muscle
internal oblique -> cermasteric fascia and muscle
external oblique -> external spermatic fascia


paramesonpehric duct in females how does it form a uterus and what else does it form with connection to what

initially runs alongside the developing gonadsas it comes down into the pelvis both of them move towards one another and at the midline they fuse to form the uterus - the wall between them breaks and they form a single cavity

also make contact with the urogenital sinus which is the site of the vagina


how is the vagina formed

the uterus/paramesonpehric ducts proliferate with the urogenital sinus forming sinovaginal bulbs which continue to proliferate and gradually push that point of contact further away - then they begin to capitate to form the vagina and a connection into the uterus


which germ cell layer does the vagina come form
what forms at the point of contact between the vagina and the outside world


hymen which has small opening for passing of menstrual blood


whats a bicornate uterus

septum has regressed completely but further up that the double uterus - kind of looks like one uterus


whats a separated uterus

a septum has formed down the uterine cavity


whats a unicorn ate uterus

failure of one duct


whats a cervical atresia

no communication between the vagina and the uterus


how do the ovaries descend

also via gubernaculum which goes through the inguinal canal and gets stuck on the paramesonephric duct so when it goes down again it pulls them together causing them to fuse
as they fuse they create the broad ligament