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#reproductive system

12 public questions tagged with this topic.

Sex determination-l

The Müllerian duct develops into:

Müllerian ducts also called paramesonephric ducts arise alongside Wolffian ducts in both sexes during early fetal development. In absence of anti-Müllerian hormone as in female embryos, ducts persist, fuse caudally and differentiate under estrogen and Wnt signaling into oviducts, uterus, cervix and upper vagina; unfused cranial portions become Fallopian tubes. In males AMH secreted by Sertoli cells induces regression via apoptosis preventing female organ development, while testosterone maintains Wolffian derivatives forming epididymis and vas deferens. Therefore developmental fate of Müllerian duct is female internal genitalia.

Ref: Gilbert, Developmental Biology, 12th ed., Chapter 17: Müllerian duct develops into female internal genitalia.

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sex determination-ll

Incorrect statement about genital ridge determination?

Designating Rspo1 as promoter of testis pathway is incorrect because genetic evidence firmly places Rspo1 in ovarian network. Rspo1 synergizes with Wnt4 to activate β-catenin signaling, promoting granulosa differentiation and directly repressing Sox9/Fgf9 male program. Loss-of-function in humans and mice results in XX masculinization, appearance of Sertoli cells, androgen production and ovotestes, not testicular failure. Gain of Rspo1 activity antagonizes testis cord formation. Testis pathway instead relies on Sry, Sox9, Fgf9, Dmrt1 and Dhh. Therefore Rspo1 belongs to ovary-promoting module alongside Wnt4, Foxl2 and β-catenin.

Ref: Gilbert, Developmental Biology, 12th ed., Chapter 6: Incorrect assignment of Rspo1 function; ovarian pathway genes.

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Fertilization in mammals-l

Translocation of sperm assisted primarily by:

After deposition in vagina, sperm translocation through cervix, uterus and into oviduct depends on both autonomous motility and female tract facilitation. Cervical mucus filters immotile sperm, uterine peristaltic contractions propel sperm rapidly toward uterotubal junction, and oviductal ciliary beating generates fluid flow that must be overcome by rheotaxis. Coordinated contractions under oxytocin and prostaglandin influence provide long-distance transport exceeding intrinsic swimming velocity. Subsequent hyperactivated motility within oviductal isthmus enables mucus penetration, ascent toward ampulla where fertilization occurs, embryo begins cleavage and early divisions for transport.

Ref: Gilbert, Developmental Biology, 12th ed., Chapter 7: Sperm transport – uterine contractions and motility in female tract.

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