In birds and reptiles, W chromosome contains the sex-determining factor. Directs differentiation of ovaries. C. Phenotypic sex . Sex accessory organs and external genitalia. In the presence of testes .
Wolffian ducts develop into epididymis, vas deferens, and seminal vesicles.
Due to testosterone. Glycoprotein secreted by fetal testes. Secretion peaks at the time Mullerian ducts regress 3. Gene is not on the Y-chromosome. Also produced by ovary, but in tiny quantities.