Which hormone is crucial for the development of male reproductive systems during embryonic growth?

Testosterone is crucial for the development of male reproductive systems during embryonic growth because it is the primary male sex hormone that promotes the differentiation of male reproductive organs. During the early stages of embryonic development, the presence of testosterone leads to the formation of structures such as the testes and the male reproductive tract. Without adequate levels of testosterone, the embryo may not develop the typical characteristics associated with male sexual differentiation, which highlights its essential role in the process.

The other hormones listed do not play the same direct role in male reproductive system development. Estrogen is primarily involved in female reproductive development, while follicle-stimulating hormone is more related to the regulation of the reproductive processes in both males and females but not directly responsible for embryonic sexual differentiation. Oxytocin, often associated with labor and bonding, does not have a role in the development of the male reproductive system during embryonic growth.