A Histochemical Investigation of the Alleviation of Thallium-induced Achondroplasia in the Embryonic Chick Femur by Sorbitol, Imidazole and Histidine

Abstract

Achondroplasia was induced in the embryonic chick by the administration of 0.6 mg of thallium sulfate onto the chorioallantoic membrane at day seven of incubation. Coinjection of sorbitol, imidazole or histidine alleviated this disease to varying degrees, depending on the particular compound and its concentration. Femurs were examined histochemically for acid mucopolysaccharide, collagen and calcium content on days ten, twelve and sixteen. When compared to controls, thallium-treated femurs contained less acid mucopolysaccharide in the cartilagenous matrix at days ten and twelve but more in the boney matrix at day sixteen. Calcium was present in greater quantities in the thallium-treated embryos at days ten and twelve but the amount was nearly equal by day sixteen. Collagen was more abundant in the thallium-treated femurs on days ten and twelve but the situation reversed on day sixteen. The minimal effective dosage for sorbitol was 3.0 umoles/egg and 10.0 umoles/egg for imidazole. Histidine did not alleviate the achondroplasia effectively at any concentration up to 12.5 umoles/egg. It is suggested that thallium produces achondroplasia by either the inhibition of acid mucopolysaccharide synthesis or its subsequent secretion into the cartilagenous matrix.