Wolffian ducts

In the early mammalian female embryo the absence of the Mullerian inhibitory substance MIS permits continuing development of the Mullerian duct, while the absence of testosterone permits the Wolffian duct to degenerate. However, positive developmental signals are also required. Among these is the protein Wnt-4, a member of a large family of locally acting signal molecules (Section 4). Wnt-4 may be needed both for oocyte development and for further suppression of male development.261... 

Turner KJ, McIntyre BS, Phillips SL, et al. (2003) Altered gene expression during rat Wolffian duct development in response to in utero exposure to the antiandrogen linuron. Toxicological Science 74(1) 114-128. 

In the genotypic female, lack of testosterone and MIS causes regression of the wolffian ducts and maintenance of the mul-lerian ducts, thus forming the female reproductive tract. " Gonadotropin activity in utero is suppressed because of high concentrations of circulating estrogens derived from the mother. ""... 

After the fetal gonads are converted into testes by SRY, testosterone and Miillerian-inhibiting substance (MIS) control subsequent sexual differentiation. MIS causes the regression of the Mullerian duct, which would otherwise develop into female genital tracts. Testosterone promotes the development of the Wolffian duct into male internal genitalia, including epididymis, vas deferens, and seminal vesicles. 

Defects in the ENS are significant in view of the association of RET with Hirshsprung s disease. The ENS derives from neural crest cells which express Ret when in the developing gut and both Gdnf and Gfr-al are expressed in the gut mesenchyme. Lack of kidneys in mutant mouse embryos is due to the failure of the ureteric bud (which expresses Ret) to develop from the Wolffian duct and expand into the metanephric blastema (which expresses Gdnf). This would normally initiate the formation of the metanephric (adult) kidney, but in the absence of ligand or receptor the blastemal cells eventually die. 

Willebrand factor 425, 1153 Wilm s tumor 221, 359 (With-no-lysine) kinase-4 (WNK4) 78 Wnt-binding proteine 294 Wolffian duct 355 Working Cell Bank (WCB) 1645 World Drug Index (WDI) 1790 World Health Organization (WHO) 1569... 

The fetal testis induces a male type of phenotypic sex development by virtue of producing two sorts of hormones. The first of these is the androgen testosterone, which triggers the formation of male structures from the Wolffian duct, the urogenital sinus, and the external genital primordia, via mechanisms considered below. The second type of fetal testicular hormone is a macromolecule, apparently a glycoprotein, that evokes involution of the Mullerian duct during normal male sex differentiation. 

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