Early changes at the epiphysis of rachitic chicks, following administration of vitamin D.

One day old chicks were fed a vitamin D-deficient diet for 3 weeks. Some were then given an oral dose of vitamin D and sacrificed at various times thereafter. The tibiae were x-rayed; demineralized sections were stained for neutral polysaccharides and sulfated mucopolysaccharides; other specimens were ashed; and others still were autoradiographed to determine their uptake of Ca(45)in vitro. Mineralization reappeared in the treated animals after 2 days, along with new P.A.S.-positive spicules. Earlier, the immature cartilage rapidly matured morphologically. At the same time, the rachitic matrix, highly concentrated in cation binder, presumably chondroitin sulfate, lost this material progressively.