10/23 Embryology of male Reproductive Flashcards
what are the Genetic; Gonadal; and Phenotypic traits of a male?
Genetic: 46XX or 46XY; Gonadal: Testis; Phenotypic: Internal ducts and external genitalia
where is the source of the masculinization of the ducts and external genitalia of a male?
the Testes produce adrogens!
Where is the bipotential gonad located in early embryo?
at the genital ridge
what is the composition of the bipotential gonad?
the coelomic epithelium, germ cells, primitive sex cords.
what are the components of the bipotential gonad?
the Germ cells, coelomic epithelium, and the primitive sex chords.
what is the molecular signal that confers competence to teh urogenital ridge, and yealds the bipotential gonad? (both genders)
SF1 and WT1
what reciprocal inhibition is present in the bipotential gonad?
Sox9/Fgf9 and Wnt4/Respondin1 the balance between these keeps the genital ridge in a bipotential state!
what will shift the balance of the bipotential gonad towards a male?
SRY gene on the Y chromosome will give a boost to Sox9/Fgf9 and down reg. Wnt4/Respondin1 and give development as a male.
on the short arm of Y chromosome, encoding 223 AA non-histone protein.
the SRY gene
what if you don’t have the SRY gene?
the gonads will become an ovary.
223 AA non-histone protein coded for on the short arm of the Y chromosome, gene activated by HMG box binding to it and bending the DNA! and is the first gene specific for testis
SRY
when is the SRY gene expressed?
only in genital ridge at the time of testis induction
where would you expect SRY and Sox9 to be expressed
SRY would be At the genital ridge in males, and SOX9 would be expressed at the genital ridge in both females and males in the biopotential gonad… until the female “track” is chosen by over expression of WNT4 and SOX9 would go way down!
what would be the phenotype of an individual with a 46xy genotype who has a null mutation in SRY or Sox9?
they would not have SRY to up reg. sox9 and therefore would choose the female tack of development!
what is the molecular signal that would be expected to lead to a male development?
SRY from the y chromosome expressed and leads to a enhancement of SOX9 expression that down regulates WNT4 (female signal) and up regulates SF1 and Other genes to lead to the development of testes.
what is the molecular signaling (genes) that lead to female development?
WNT4 wins the reciprocal inhibition with SOX9 and expresses DAX1 that down regulates SOX9. WNT4 also leads to other genes (TAFII 105) along with DAX1 that will then lead to Ovaries
what structures develop if SRY upregulates Sox9 instead of ovary follicle cells from the ceolomic epithelium.
you would get male sertoli cells.
in males and females…what does the gonadal ridge develop into?
Sex cords and connective tissue
primitive sex cords grow into the gentital ridge from what tissue origin
the mesonephros.
what will incorporate into the sex cords developing out of the genital ridge from the mesonephros?
the primitive germ cells! from the yolk sack
what will develop from the outer cords in the genital ridge?
the seminiferous tubules and contain sertoli cells
What develops from the deeper cords of the genital ridge?
the rete testis
The develping teste will contact and make efferent ducts with what tubule?
the mesonephric tubules
converts the genital ridge cells tot eh bipotential gonads
SF1
required for Sox 9 expression and upregulated by SRY/Sox9
SF1
promotes testosterone production by leydig cells
SF1
Promotes MIS (AMH) production by sertoli cells
SF1
what is the outline of gonad development in males from the UG ridge?
UG ridge (get SF1 / WT1) develope bipotential gonad (get SRY SOX9) then get testes and then get sertoli cells and Leydig cells (use SF1) to then get AMH (from sertoli) and Testonsterone (from leydig cells)