Final answer:
During sex differentiation, testosterone stimulates the development of the Wolffian duct for male reproductive structures, while Anti-Müllerian hormone from sustentacular cells suppresses the Müllerian duct in males. In females, without these substances, the Wolffian duct degenerates and the Müllerian duct develops into female reproductive organs.
Step-by-step explanation:
During sex differentiation, the presence of testosterone stimulates development of the Wolffian duct, whereas the presence of substances secreted by sustentacular cells (such as Anti-Müllerian hormone) inhibits development of the Müllerian ducts. In males, testosterone is responsible for developing the male reproductive tract, which includes structures such as the epididymis, ductus deferens, and seminal vesicles. Conversely, sustentacular cell secretions lead to the degradation of the female-specific Müllerian duct, preventing the development of female internal reproductive structures like the uterus and uterine tubes in males.
During female fetal development, in the absence of testosterone and sustentacular cell secretions, the Wolffian ducts degenerate, and the Müllerian ducts develop into the internal female reproductive organs, such as the uterine tubes and uterus.