Question

Provide an overview of sexual differentiation of the mammalian gonads, ducts, and external genitals. That is, describe the chain of hormonal events that sculpt the mammalian fetus into a male or female form. In your answer, make sure to describe what the SRY chromosome is.

Answer 1

Y chromosome is the smallest and unique chromosome found in mammalian male. Y chromosome has SRY region present on it. During seventh week SRY region produces SRY Protein (Testes determining factor-TDF). TDF as a transcription factor will take action on gonadal ridge cells and help them to differentiate into testosterone producing cells. With the help of hCG (Second signal from placenta) the testosterone producing cells release testosterone. Testosterone stimulate wolfian duct to differentiate into different parts of male reproductive system. Simultaneously, non ridge cells will release MIS i.e. Mullerian Inhibitory Substance that will disintegrate Mullerian duct. Thus the fetus will develop as male.

However, for development of female fetus Mullerian duct doesn't require any signal, the fetus will develop as female fetus by default.