Effects of lithium chloride on embryos ofOphryotrocha labronica LaGreca and Bacci

Cleavage embryos of the polychaeteOphryotrocha labronica were exposed to LiCl solutions of various strength for up to 4 days. High concentrations strongly inhibited development and led to endodermal protrusion, whereas moderate concentrations permitted development of larvae, although with characteristic disturbances as a consequence. Ultrastructural analyses of embryos exposed to moderate concentrations demonstrated manifest changes already during the first 24 hours, viz. of lipid droplets and yolk granules, the latter being ruptured and the contents dispersed to an extent far surpassing that at normal development. The premature widespread splitting of yolk granules by LiCl was confirmed by quantitative measurements on embryos which during oogenesis had their yolk granule DNA selectively labelled with³H-thymidine.