Retinoic acid plays an essential role in spermatogenesis, assisting withdevelopment of the blood–testis barrier (BTB), spermatogonial differentiation,and spermiation.72 Male mice with knock-outs of the retinoic acid receptorα (RARα) are infertile.73 In the late 1950s, researchers studying antiparasiticsnoted that rats receiving retinoic acid inhibitors developed the unintendedconsequence of infertility. This evidence concerns the gene RARA and Infertility.