Sex determination Flashcards
(26 cards)
When is sex determined?
At fertilisation
What gene determines sex?
Lack of or presence of SRY gene on Y chromosome
If Y chromosome contains SRY gene what does lead to?
Development testis
If no sex determining region of SRY what does lead to?
Ovary development
What does non-functional X in female gonads condense to form?
Barr body
If +SRY
If -SRY
+SRY lead to development testes
-SRY development ovary
What forms genital organs?
Intermediate mesoderm
Genital ridge
What two ducts are present?
Wolffian ducts
Mullerian ducts
Where do germ cells for sperm and ova come from?
Yolk sac of hindgut
What duct system present in males?
Wolffian duct (mullerian regresses)
What cells responsible for regression of mullerian duct in males?
Sertoli cells- produce mullerian inhibitory factor (MIF)
Leads to testis determining factor
Influence formation male gonads
What does the SRY gene induce?
MIF- regress mullerian
Outline how male duct formed?
1) SRY induces MIF
2) Sertoli cells produce MIF
3) MIF leads to testis determining factor
4) Mullerian regresses
Wolffian duct remains
What produces testosterone?
Leydig cells
What is the wolffian duct converted into? (4)
Epididymis
Vas deferens
Ejaculatory duct
Seminal vesicles
What effect does testosterone have on testes?
Cause testes descend into scrotum
Function of DHT (from testosterone)?
Development penis, scrotum, prostate
What do sertoli cells produce?
Mullerian Inhibitory factor
Males
Females
What duct is present?
Males- wolffian
Female- mullerian
How is mullerian duct formed in females?
1) No SRY gene
2) No MIF produced meaning mullerian system develops
3) Mullerian duct produces- fallopian tube, uterus, upper 2/3 vag
Where does the lower 1/3 vagina and external genitalia develop from?
Urogenitial sinus
Name 3 things the mullerian duct produces?
Fallopian tubes
Uterus
Upper 2/3 vagina
Name 2 things urogenital sinus produces?
Lower 1/3 vagina
Ecxternal genitalia
Presence of SRY gene means?
Male- MIF produced
