皮肤对维生索D的合成、贮存和释放具有特殊的重要性.现已确定,维生素D_3是人和动物经紫外线照射后,由皮肤中含量丰富的前质——7—去氢胆固醇转变而成.近来,表皮光作用产生VitD_s的精确程序已完全确立.在光化学反应中形成的是构成VitD_3唯一来源的VitD_3原.后者不耐热,经过一个依赖温度的 The skin is of particular importance for the synthesis, storage and release of vitamin D. It has now been determined that vitamin D_3 is produced by the conversion of the skin’s abundant precursor 7-dehydrocholesterol Recently, the precise procedure for the generation of VitD_s by epidermal light has been completely established, and the photodissociation of VitD_3, the sole source of VitD_3, is formed in the photochemical reaction, which is not thermolabile and undergoes a temperature-dependent