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#male reproductive system

7 public questions tagged with this topic.

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.

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Fertilization in mammals-l

Primary function of sperm midpiece:

Sperm midpiece is short segment posterior to neck connecting head to principal piece of flagellum, characterized by helical arrangement of elongated mitochondria wrapped around outer dense fibers and axoneme. Mitochondria generate ATP via oxidative phosphorylation fueling dynein-dependent flagellar beating, essential for progressive motility through female tract. Though glycolysis in principal piece also contributes, midpiece mitochondrial respiration supports hyperactivation and sustained motility. Structural defects in mitochondrial sheath cause asthenozoospermia. Midpiece therefore functions as energy powerplant translating metabolism into mechanical propulsion of genetic payload toward egg efficiently for fertilization and conception.

Ref: Gilbert, Developmental Biology, 12th ed., Chapter 7: Sperm midpiece mitochondria, ATP production and flagellar motility.

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