Effect of 1,25-dihydroxycholecalciferol on the duodenal villi and alkaline phosphatase in the developing chick embryo.

Administration of 1,25-(OH)2D3 to developing 14-day chick embryo gave precocious induction of alkaline phosphatase in 20-day chick embryonic duodenum. 1,25-(OH)-2D3-induced alkaline phosphase involved in changes in Km and Vmax values. Furthermore, polyacrylamide gel disc electrophoresis of n-butanol-solubilized alkaline phosphatase from control and 1,25-(OH)2D3-treated chick embryonic duodenum revealed that 1,25-(OH)2D3 involved the transformation of neuraminidase-resistant fast migrating form to the neuraminidase-sensitive faster migrating one. Scanning electron microscopic data showed that the injection of 1,25-(OH)2D3 stimulated the elongation of duodenal microvilli, although there was no effect on the duodenal absorptive epithelial cell height.