THE INDEPENDENT ORIGIN OF AMPHIBIAN RED CELLS AS SHOWN BY DIFFERENTIAL SUSCEPTIBILITY TO X-RAYS

Abstract

45 early neurula stage embryos of Ambystoma jeffersonianum ex posed to 1000 r of x-rays included 9 with no blood cell formation from the blood island and 21 with reduced and retarded blood cell formation. The heart and endothelium were formed, in all cases, in these and 5 other series of embryos treated. The blood island is not only an angio-blast region but also a specifically limited and specialized source of red cells in the prehatching stages. Since the heart and endothelium were never eliminated by x-ray ex posure their anlage evidently is physiochemically as well as morphologically and positionally distinct from that of the red blood cells.