Yan Genital System Flashcards
When is sex determined?
at fertilization (presence or absence of Y chromosome)
When does male/female morphology develop?
7th week
What are genital (gonadal) ridges and what are they derived from?
the precursor to the genitals
epithelium and condensation of underlying mesenchyme
When do germ cells appear on genital ridges?
at the 6th week
Explain how the gonads begin to develop?
PGCs-> dorsal mesentery of the hindgut->primitive gonads-> invade gonadal ridges-> development
Where do primordial germ cells originate and what are they?
endodermal cells in the wall of the yolk sac close to allantois
How do the primordial germ cells migrate from the yolk sac to the dorsal mesentery of the hindgut?
by ameboid movement
When do the PGCs arrive at the gonads?
at the beginning of 5th week
When do the PGCs invade the gonadal ridges?
at 6th week
If you don’t have PGCs will you get testes and ovaries?
NO, you need PGCs to induce the development of the testis or ovary
What happens once the PGCs arrive at the genital rides?
Epithelium of genital ridges proliferate and penetrate underlying mesenchyme to turn into primitive sex cords
When the PGCs arrive at the genital ridges and penetrate the underlying mesenchyme, it turns into the primitive sex cords. Are these sex cords of males or females?
neither, they are indifferent and can later turn into either or
How do you make PGCs turn into testis?
PGCs will have a Y chromosome with SRY (TDF) gene that will make the primitive sex cords turn into testis and medullary cords. These medullary cords will then converge at the rete testis and are covered by tunica albuginea
In the fourth month, testis cords are composed of (blank) and (blank) (derived from the surface epithelium. Somatic cell component)
PGCs and Sertoli cells
Leydig cells, derived from the original mesenchyme of the gonadal ridges, lie between the (blank). Testosterone production starts at week 8.
testis cords
(blank) is important for the development of the genital ducts and external genitalia.
Testosterone
Testis cords remain solid until (blank)
puberty
Explain what happens to the testis cords after puberty?
the cords undergo canalization (turn into canals) and become seminiferous tubules that join at the rete testis. These then connect to the efferentes ducts which link to the mesonephric duct to become ductus deferens.
How do you make ovaries by PGCs?
Lack of Y chromosome results in sex cord dissociation into irregular cell clusters and degeneration of medullary cords. Cortical cords then develop from epithelium and penetrate underlying mesenchyme. This cord splits into cell clusters surrounding PGCs and the PGC become oogonia and surround cells to become follicular cells.
So what is the major difference in differentiation between ovaries and testes?
the Y chromosome making sex cord persist
Unspecialized gonads and 2 sets of reproductive ducts exist until (blank)
week 6
What is the paramesonephric duct also called?
What is the mesonephric duct also called?
the mullerian duct
the wolffian duct
What duct must degenerate to get rid of female parts so that you will have a male?
mullerian ducts
How does the Y chromosome degenerate the mullerian ducts so that the baby will be male?
The sertoli cells secrete anti-mullerian hormones
Once you have testis you will make interstitial cells which will make (blank) and thus make all the internal and external genitalia of males.
testosterone
What makes these: Urethra Prostate Penis Scrotum
DHT
What makes these: epididymis vas deferens seminal vesicles ejaculatory duct
Testosterone (only if they have SF1)
(blank) gene activates a cascade of development events which create the testis and thus all the internal and external male genitalia
SRY
Since females do not have SRY, they will create ovaries and thus their follicles will secrete (blank) which will convert the mullerian duct (paramesonephric duct) into the (blank)
estrogen
oviducts
What three factors do you need to push the genital ridge into differentiation status?
SF1
WT1
LHX9
What 2 factors do you need to turn the sex cord into the ovary?
What 2 factors do you need to turn the sex cord into the testis?
DAX1, WNT4
SRY,SOX9
What do leydig cells need to make testosterone? and what will testosterone do?
SF1
convert wolffian duct into male genitalia
What does DHT do to the genital tubercle, urogenital sinus?
converts it into the penis, prostate
The upper portion of mesonephric duct starts to branch and form (blank)
efferent duct
The lower portion of the mesonephric duct starts to elongate and branch to make the (blank)
epididymis
The lowest portion of the mesonephric duct elongates and forms (blank) and (blank)
vas deferens and seminal vesicles
Efferent ducts, epididymis, vas deferens, seminal vesicles are all derived from (blank) under the influence of testosterone.
mesonephric ducts
In the male genitalia, the excretory tubules remain while (blank) regress and change.
mesonephros
In the male, epigenital tubules in contact with rete testis becomes (blank)
efferent tubules