Effects of Mild and Severe Vitamin B(1) Deficiencies on the Meiotic Maturation of Mice Oocytes

We investigated the effects of vitamin B(1) deficiency on the meiosis maturation of oocytes. Female Crl:CD1 (ICR) mice were fed a 20% casein diet (control group) or a vitamin B(1)–free diet (test group). The vitamin B(1) concentration in ovary was approximately 30% lower in the test group than in the control group. Oocyte meiosis was not affected by vitamin B(1) deficiency when the deficiency was not accompanied by body weight loss. On the contrary, frequency of abnormal oocyte was increased by vitamin B(1) deficiency when deficiency was accompanied by body weight loss (referred to as severe vitamin B(1) deficiency; frequency of abnormal oocyte, 13.8% vs 43.7%, P = .0071). The frequency of abnormal oocytes was decreased by refeeding of a vitamin B(1)–containing diet (13.9% vs 22.9%, P = .503). These results suggest that severe vitamin B(1) deficiency inhibited meiotic maturation of oocytes but did not damage immature oocytes.