Maternal vitamin B12 deficiency affects spermatogenesis at the embryonic and immature stages in rats

To evaluate the role of cobalamin (Cbl) on spermatogenesis, the effect of dietary vitamin B(12) deficiency on early spermatogenesis was histologically investigated in male fetuses and newborns in the first filial generation (F(1) males) of rats. There was no difference in the number of gonocytes and supporting cells of Sertoli in the gonad in male fetuses on day 16 of gestation and in the testes in F(1) males at 0 days of age between vitamin B(12)-deficient (VB12-D) and vitamin B(12)-supplemented (VB12-S) groups. However, at 21 days of age, a decreased number of spermatogonia and no spermatocytes were observed in the VB12-D group. Numerous TUNEL positive cells were located among spermatocytes of the spermatogenic epithelium. The ultrastructural features examined using transmission electron microscopy were considered to be indicative of apoptosis. The incidence of seminiferous tubules having apoptotic cells was 51.5% in the VB12-D group. At 60 days of age, aplasia of the spermatids and spermatozoa was detected in the VB12-D group. In the connective tissue between the seminiferous tubules, many interstitial Leydig cells and blood vessels were observed in the VB12-D group, as compared with the VB12-S group. These changes produced by vitamin B(12) deficiency can be reversed by providing a VB12-S diet after weaning at 21 days of age. From these findings, such a vitamin B(12) deficiency during gestation and lactation could affect the germ cells and especially damage spermatocytes in F(1) male rats, which indicates that Cbl may be an essential constituent in the meiosis of spermatogenesis.