Germ Cell Differentiation in Starfish: The Posterior Enterocoel as the Origin of Germ Cells in Asterina pectinifera: (starfish/germ cells/PGC/posterior enterocoel/haemal sinus).

The origin of germ cells of Asterina pectinifera was traced back to the posterior enterocoel (PE) of 2-day bipinnaria by two steps. First, the cellular cluster, composed of presumptive germ cells in the coelomic epithelium at brachiolaria stage, was confirmed to be the origin of the aboral haemal sinus located near the hydroporic canal (HC-AHS) by continuous observation of the formation process of HC-AHS. Second, the origin of the cluster was traced back to the PE of 2-day bipinnaria by comparison of the number of the presumptive germ cells in microsurgically PE-removed bipinnariae with that of non-operated control larvae. A summary of the differentiation of germ cells in Asterina pectinifera is given/presented.