Acció dels andrògens en el testicle: un paper per a la meiosi

The role that androgens play in spermatogenesis still remains enigmatic: whereas their involvement
is absolutely vital to the initiation and maintenance of the normal spermatogenic
process, their specific role is yet to be defined. Androgens, like other steroid hormones, act via
their corresponding receptor termed the androgen receptor (AR). To date, there is little evidence
to support the notion that there are multiple forms of AR as is the case for the estrogen-estrogen
receptor system. Thus, the question of how androgens manifest their action on spermatogenesis
becomes one of defining two processes: First, the cell types within the testis that are capable of
responding directly to androgen stimulation must be identified with absolute certainty. Specifically,
this question can be stated as what cell types in the testis express AR. Second, given that
the ligand-bound AR serves as a transcription factor, the question then becomes what are the
genes turned on or off in AR positive cells in response to androgen stimulation? Until these two
questions are unequivocally answered, the mechanism of how androgens regulate spermatogenesis
will remain speculative at best. In this review we present evidence that androgens act
solely at the level of the somatic cells of the testis, including Sertoli cells, Leydig cells, peritubular
myoid cells and smooth muscle cells surrounding blood vessels. In addition, we discuss
the likely possibility that androgens are indispensable for the onset of meiosis, albeit how they
accomplish this remains a mystery.