Effects of Mild and Severe Vitamin B Deficiencies on the Meiotic Maturation of Mice Oocytes.

We investigated the effects of vitamin B deficiency on the meiosis maturation of oocytes. Female Crl:CD1 (ICR) mice were fed a 20% casein diet (control group) or a vitamin B-free diet (test group). The vitamin B concentration in ovary was approximately 30% lower in the test group than in the control group. Oocyte meiosis was not affected by vitamin B deficiency when the deficiency was not accompanied by body weight loss. On the contrary, frequency of abnormal oocyte was increased by vitamin B deficiency when deficiency was accompanied by body weight loss (referred to as severe vitamin B deficiency; frequency of abnormal oocyte, 13.8% vs 43.7%, = .0071). The frequency of abnormal oocytes was decreased by refeeding of a vitamin B-containing diet (13.9% vs 22.9%, = .503). These results suggest that severe vitamin B deficiency inhibited meiotic maturation of oocytes but did not damage immature oocytes.