The VDR protein has been found in the prostate, seminal vesicles, epididymis, and also in germ cells, especially spermatogonia, spermatocytes, and Sertoli cells (139, 142). VDR protein expression has been found in animal sperm but has been suppressed in the tail of the epididymis (139, 143). In the same context, testosterone synthesis enzymes in the testes appeared to be reduced in mice fed the vitamin D deficiency (VDD) diet (144). This evidence concerns the gene VDR and vitamin D deficiency.