过量的维生素A对黑斑蛙早期胚胎发育的影响

Effects of Vitamin A Excess on Early Embryonic Development of Rana Nigromaculata

维生素Ａ（ＶｉｔａｍｉｎＡ）又称视黄醇（ｒｅｔｉｎｏｌ），对维持动物正常视觉功能、上皮组织的完整与健全以及促进正常生长发育是必不可少的，但过量的维生素Ａ能导致畸形胚胎的产生．本文以１０－５ｍｏｌ／Ｌ和１０－４ｍｏｌ／Ｌ维生素Ａ处理黑斑蛙（Ｒａｎａｎｉｏｍａｃｕｌａｔａ）早期胚胎，产生了不同程度的畸形，例如小眼头正常、小眼畸头、无眼畸头等；而且随着维生素Ａ浓度和处理时间的增加，畸形率增高，畸形程度加剧；过量的维生素Ａ也减少了色素细胞的形成，但并不抑制原肠作用及随后的神经诱导，它很可能是直接影响神经外胚层的区域性分化．

Vitamin A(i. e. retinol)is necessary to maintain normal optical function,keep epithelial tissue intact and improve the development and growth of animal. Meanwhile,vitamin A excess can cause abnormal embryos. In this paper,early Rana nigromaculata embryos were treated with 10-5mol/L and 10-4mol/L vitamin A and it resulted in various abnormal embryos, including the kinds of essentially normal head with small eyes, abnormal head (shortened the forebrain and midbrain)with small eyes and abnormal head (lack most or all of the forebrain and midbrain)without eye,etc. As the concentration of Vitamin A and the time of treatment increased the rateand degree of malformation enhanced. Vitamin A excess also reduced the formation of pigment cell. The gastrulation and consequently neural induction were not inhibited when embryos were treated with vitamin A at the stage of blastula,gastrula and neurula. It might directly affect regional differentiation in the neurectoderm.