Flashcards in Female Repro Embryology Deck (55)
What's the male duct?
Wolffian / mesonephric.
What's the female duct?
Mullerian / paramesonephric.
Up to what point are male and female internal ductwork similar?
4 factors that males need to be male?
1) Testis-determining factor (TDF)
2) Mullerian Inhibiting Factor
What factors to females need to be female?
Estrogen and Wnt4
Name 3 major structures formed from the Mullerian duct?
3) Upper part of the vagina.
From which germ layer do the mesonephric and paramesonephric ducts arise?
What does the mesonephric duct do when it's first formed?
Associates with glomeruli... guides formation of uriniferous tubules.
Which develops first: Mesonephric or paramesonephric ducts?
Mesonephric ducts appear first.
Are primordial germ cells (PGCs) born in the genital ridge? Where do they come from?
No, the PGCs must migrate to the genital ridge from their origin in the wall of the yolk sac.
What happens to the yolk sac?
It gets incorporated into the gut tube...
What does the arrival of the PGCs in the genital ridge stimulate?
Arrival of the PGCs stimulates the formation of sex cords--> the support cells of the gonads
What gene governs sex-based differences in supporting cells of the sex cords? What does it encode?
SRY (located on the Y chromosome) - encodes TDF.
The development of which cells is first induced by TDF from PGCs? What is the first action of those cells?
Sertoli cells. Their first action is to inhibit spermatogenesis in utero?
What endocrine cells to Sertoli cells induce? What do those cells make?
Leydig cells, which make testosterone.
How is female differentiation turned off in males? What cells do this?
Mullerian inhibiting factor (aka anti-Mullerian hormone) made by Sertoli cells -> causes Mullerian duct degeneration.
What must testosterone be converted to have an effect on external reproductive structures?
DHT (the Leydig cells are responsible for turning testosterone into DHT)
What supporting cells are induced by PGCs in females?
granulosa / follicular cells
Endocrine cells induced by follicular / granulosa cells? What do they make?
Theca cells, which make estrogen.
Review: In what phase of Meisosis are primary germ cells in females arrested?
Primary oocytes are arrested in Prophase of Meiosis I.
In what way are male and female sex cords in different locations? Why is this important?
Male: Medullary, more in the interior.
Female: Supporting cells are more cortical.
Males are more interior because they lead to ducts that are continuous with the outside world (via the mesonephric duct).
What drives the paramesonephric ducts to partially fuse?
Estrogen made by theca cells (which were induced by follicular cells induced by PGCs).
3 structures that result from partial fusion of the paramesonephric ducts inferiorly?
Uteus, cervix, and upper vagina. (note that the Fallopian tubes are from the unfused parts of the ducts).
From what germ cell layer originates the epithelium of the lower 1/2 - 2/3 of the vagina?
Epithelium there is derived from endoderm.
What embryological structure gives rise to the bladder and urethra?
The urogenital sinus - derived from endoderm.
The bladder, urethra, lower vagina, vestibule, and gut lining all come from...
What structure is formed when the paramesoneprhic tubules bring together a peritoneal fold and fuse and all that stuff? What two areas does this define?
The broad ligament of the uterus.
This creates the rectouterine and vesicouterine pouches.
What prevents the gubernaculum from drawing the ovary down through the inguinal canal?
Paramesonephric duct fusion blocks the path.
What ligament is at the base of the uterus / cervix? What courses through it?
The cardinal ligament. The uterine artery and vein course through it.