Androgenic actions are determinant for sperm production and function and, thus, for male fertility. Androgens exert their effects by

interaction with the androgen receptor (AR), a transcription factor that modulates gene expression in target-cells and tissues. Variants of AR protein have been identified in the testis, revealing a new complexity in androgen signaling pathways. In addition, androgens may evoke responses by controlling intracellular calcium (Ca2+) levels and/or activating Ca2+-dependent pathways. However, until recently the knowledge about the role of androgens controlling testicular expression and activity of membrane and intracellular Ca2+ regulatory proteins was very limited or inexistent. Also the function of Ca2+ in sperm maturation in the epididymis only recently started to be known. This review describes recent advances identifying new AR isoforms in the testis, as well as the novel actions of androgens as modulators of Ca2+ homeostasis

in reproductive tract discussing the consequent impact for male fertility.