AUTORADIOGRAPHIC STUDIES OF THE UTILIZATION OF S35-SULFATE BY THE CHICK EMBRYO

Abstract

Autoradiograms reveal a selective utilization of S35 by the chick embryo as early as stages 3 and 4, where an anterior-posterior gradient of selectivity in the head process is seen. The notochord shows an early isotope accumulation at the site of a later appearing thin ring of chondroitin sulfate. Intracellular accumulation by the chondroitin-forming cells and by cells which later develop into chondroblasts was seen. S35 accumulated in the subendocardial jelly and in the endocardium, indicating that the jelly may be an endocardial product. An accumula-tion of the isotope also occurs in the region of the forming basement membrane of the gut, showing that sulfate is some way associated with the differentiation of this membrane. S35 also was found in the gastric mucin, a product of the gastric epithelium. The pattern of utilization of S35 was followed through stage 34.