Genital Development Flashcards
(34 cards)
The sex of the embryo is determined at fertilization based on whether the secondary oocyte is fertilized by:
- X-bearing sperm or a Y-bearing sperm.
- Y-bearing sperm = embryo becomes male.
How does the Y-chromosome induce an embryo to become male?
- sex-determining region of the Y chromosome (SRY).
- SRY codes for Testis Determining Factor (TDF).
- TDF will cause the gonadal ridge to develop into a testis.
Steps in embryo development into a male:
- Y-chromosome contains SRY.
- SRY codes for TDF.
- TDF induces testis development.
- Testis produce testosterone.
- Testosterone induces development of the rest of male system.
- Sertoli cells of the testis produce MIF.
- MIF prevents the paramesonephric ducts from developing into the female genital tract.
Sex-determining region of the Y chromosome (SRY) codes for:
- Testis Determining Factor (TDF).
- TDF will cause the gonadal ridge to develop into a testis.
When a testis develops, what cells of the testis produce testosterone?
Leydig cells
When a testis develops, what cells of the testis produce Müllerian Inhibiting Factor (MIF)?
Sertoli cells
Function of Müllerian Inhibiting Factor (MIF):
- prevents the paramesonephric (Müllerian) ducts from developing into the female genital tract (uterine tubes, uterus and part of the vagina).
Development of a normal male genital system is dependent on:
- SRY region of the Y chromosome.
- TDF, testosterone, and MIF.
Source of primordial germ cells that ultimately lead to gonad formation:
- wall of yolk sac.
- migrate to and induce gonadal ridge to develop into a gonad.
- give rise to cells that enter meiotic cycle to form gametes.
A gonad will not develop if what cells do not reach the gonadal ridge?
primordial germ cells in the wall of yolk sac
The male testis develops from the gonadal ridge which is on the medial side of:
the mesonephros.
Effect of testosterone on the mesonephros:
- mesonephric tubules become efferent ductules.
- mesonephric duct becomes epididymis and the ductus deferens.
- MIF causes degeneration of paramesonephric (Mullerian) ducts.
Primary source of male reproductive tract:
- mesonephric ducts
- paramesonephric ducts degrade
Primary source of female reproductive tract:
- paramesonephric ducts
- mesonephric ducts degrade
Formation of paramesonephric ducts:
- invagination of coelomic epithelium.
- lateral portion of the urogenital ridge.
- forms uterine tube.
Since the uterine tube is formed by an invagination of the coelom, the uterine tube is continuous with and opens into the:
- peritoneal cavity
- Oocyte gets into uterine tube via first passing through peritoneal cavity during ovulation.
In females, the right and left paramesonephric ducts meet and fuse in the midline to form:
the uterus.
In females, how do the fused paramesonephric ducts lead to formation of the vagina?
- fused paramesonephric ducts contact urogenital sinus.
- endodermal wall of urogenital sinus thickens to form a pair of sinus tubercles.
- sinus tubercles fuse and lengthen to form vaginal plate.
- vaginal plate hollows out via apoptosis.
The fused paramesonephric ducts give rise to what structures of the female reproductive tract?
- uterine tubes
- uterus
- cervix
- upper 1/3 of vagina.
The urogenital sinus gives rise to what structures of the female reproductive tract?
- Lower 2/3 of vagina
- hymen
- vestibule
- bladder
- urethra
Seminal vesicles origin in males:
- mesonephric ducts forms evaginations at the caudal end.
- evaginations become seminal vesicles.
The merging of the seminal vesicle duct with the mesonephric duct (ductus deferens) forms the:
- ejaculatory duct
- (remainder of mesonephric duct/ductus deferens distal to seminal vesicle branch)
Prostate origin in males:
- urogenital sinus develops multiple endodermal evaginations which grow into the surrounding mesenchyme.
- give rise to the prostate.
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