The blastocoelic fluid of sea urchin embryo induces exogastrulation

Abstract

Abstract The exogastrula‐inducing activity of the blastocoelic fluid of sea urchin embryo was demonstrated by adding it to the culture medium of the late blastula stage. The active substance was separated by gel filtration and ultrafiltration, and its molecular weight was found to be in the range from 10,000 to 50,000. The activity was destroyed by trypsin and heat treatment. Since the treated embryos developed normally into pluteus larvae, except for the extrusion of archenteron toward the outside, the morphogenetic activity of the blastocoelic fluid was assumed to be exerted on the endoderm. Close examination of the exogastrulation process suggests that the evagination was due to some force pushing the endodermal plate toward the outside of the embryo.