Skip to content
Login Register

#testis development

2 public questions tagged with this topic.

Sex determination-l

Which molecule initiates testis development by activating Sox9?

Testis determination initiates when Sry protein briefly expressed in XY bipotential gonads binds testis-specific enhancer of Sox9 together with Sf1, triggering dramatic Sox9 upregulation in pre-Sertoli precursors. Elevated Sox9 establishes feed-forward loop involving Fgf9 and prostaglandin D2 maintaining high Sox9 and repressing β-catenin/Wnt4 ovarian signals. Sox9 subsequently activates Dhh for Leydig specification, Amh for Müllerian regression and collagen genes organizing testis cords and supporting germ cell quiescence. Without Sry, Sox9 remains low permitting ovarian differentiation via Wnt4, β-catenin and Foxl2 pathways.

Ref: Gilbert, Developmental Biology, 12th ed., Chapter 6: Sry initiates testis by activating Sox9.

View Details
sex determination-ll

Testis development requires:

Testicular organogenesis requires sequential action of Sry and Sox9 in supporting cell lineage. Sry provides transient trigger in XY genital ridge elevating Sox9 above threshold in pre-Sertoli cells; Sox9 then sustains expression via Fgf9-Pgd2 positive feedback, forms Sox9/Fgfr2 loop and represses ovarian β-catenin pathway. Sox9 activates Dhh for Leydig differentiation, Amh for Müllerian regression and extracellular matrix components forming basal lamina of testis cords. Combined functions establish Sertoli niche, induce quiescence of XY germ cells and vascular pattern. Deletion of either causes XY sex reversal.

Ref: Gilbert, Developmental Biology, 12th ed., Chapter 6: Sry and Sox9 required for testis formation.

View Details