Sexual Differentiation & Descent of Gonads Lecture Flashcards
When does the adrenal gland/suprarenal gland start developing?
4th wk
Where does the cortex of the adrenal gland come from?
Coelomic mesothelium cells that bilaterally (T6-T12) line the posterior abdominal wall
Where does the medulla of the adrenal gland come from?
Neural crest cells - ultimately forms chromaffin cells (norepinephrine)
In the 5th month, the fetal adrenal cortex is huge (75% androgens & glucocorticoids), but will shrink after birth. It receives _____ stimulation (__) to produce steroid hormones such as __.
Adrenal cortex receives hypothalmo-hypophysial stimulation (ACTH) to produce steroid hormones such as glucocorticoids
The adrenal cortex has 3 layers (steroids): Outermost to innermost
Zona glomerulosa
Zona fasiculata
Zona reticularis
The adrenal ____ has cells that make norepinephrine and epinephrine.
Medulla
Adrenal cortical hyperplasia - overproduction of androgens; could lead to
female pseudo-intersex problems
Male reproductive system
- Testis
- Seminiferous tubules (germ cells &Sertoli cells)
- Leydig cells
- Rete testes
- Epididymis
- Vas deferens
- Urethra
Female reproductive system
Ovary Follicles & germ cells Fallopian tube Uterus Vagina Urethra
Development of the urogential system begins at the start of week __ and ends in the third trimester.
4
Week 4: Forming the gonadal blastema (primitive gonad).
Primordial germ cells in the umbilical vesicle/yolk sac migrated up the ___ of the gut and entered the embryo proper to the medial aspect of the ____ (primitive kidneys).
This forms the ___ - thickened coelomic epithelim.
Formation of the gonadal blastema:
- Primordial germ cells in the yolk sac migrated up the dorsal mesentery.
- Entered embryo proper medial to the mesonephros.
- Formed gonadal ridge.
- Sex cords
The gonadal blastema (indifferent until wk7) are derived from what 3 cell types/sources?
- Coelomic epithelium
- Mesonephric tubules and mesenchyme
- Primitive germ cells
Weeks 4-7 is the
Indifferent stage: external genitalia between male and female are indistinguishable
In ____, the medulla gives rise to medullary cords. In ____, the cortex gives rise to cortical cords.
Testes- medullary cords
Ovaries-cortical cords
What drains the mesonephros? What does it give rise to?
Mesonephric duct
Becomes epididymus in males
In week 7, those primordial germ cells from the yolk sac that entered the embryo proper are now ___.ing
Differentiating such that you can distinguish between a male and female gonad.
Ectopic germ cells
Primitive germ cells don’t go where they’re supposed to go –> can form yolk sac tumor, but don’t form ectopic gonads.
The Y chromosome defines the sex of embryo at feritlization. What does it have that causes morphologic change in week 7?
Testis-determining factor: drives development the primary sex cord that extend into the medulla.
Because females don’t have TDF, they will develop ovaries instead.
Primary sex cord later becomes ___, which house the ____ and __.
Seminiferous tubules, which house the maturing spermatogonia and sertoli cells
Sertoli cells’ 2 functions
- Nurture developing spermatogonia.
- Produces Anti-mullerian hormone (AMH): causes mullerian duct to degenerate
Spermatogonia in the sertoli cells mature into spermatids that then go out the __ and the _.
Leave via tubuli recti and reti testis
Anti-mullerian hormone from Sertoli cells causes…
- Paramesonephric (Mullerian) ducts to degenerate
- ___ cells in the ____ to differentiate into ___, which secrete ___.
Mesenchymal cells in the gonadal ridge to differentiate into Leydig cells, which secrete testosterone & dihydrotestosterone
What causes the seminiferous tubules to canalize, mature, and commence spermatogenesis at puberty?
Testosterone- it also induces other pubertal changes
What causes the indifferent external genitalia in the male to differentiate into a penis and scrotum?
Dihydrotestosterone
