Embryonic chick intestine in organ culture: response to vitamin D 3 and its metabolites

Embryonic chick intestine maintained in organ culture responded to vitamin D(3) and its metabolites 25-hydroxycholecalciferol and 1,25-dihydroxycholecalciferol by synthesis of calcium-binding protein and enchanced calcium-45 uptake. The dihydroxy metabolite was by far the most potent inducer of the protein and also acted more rapidly than vitamin D(3) to stimulate isotope uptake. Despite its lower potency, vitamin D(3) itself was effective.