The presence of which protein promotes the formation of testes?

The presence of the transcription factor encoded by the SRY gene is crucial for the development of testes. The SRY (Sex-determining Region Y) gene is located on the Y chromosome and plays a key role in male sex determination. When expressed, the SRY protein triggers the formation of testes by influencing the development of indifferent gonadal tissue into testicular tissue.

This process involves the activation of various downstream genes that lead to the differentiation of Sertoli cells and Leydig cells, which are essential for the production of sperm and male sex hormones, respectively. The formation of testes subsequently leads to the development of male secondary sexual characteristics and the production of testosterone, further driving male differentiation.

The other proteins mentioned do not directly promote the formation of testes; instead, they are involved in different aspects of sexual development or reproductive processes. For instance, estrogen and progesterone are primarily associated with female reproductive functions, while testosterone is produced after testes have formed and is responsible for male sexual characteristics. Therefore, the transcription factor from the SRY gene is the pivotal factor in initiating testis formation.