The effects of partial hypoblast removal on the cell morphology of the epiblast in the chick blastoderm.

The hypoblast of early-primitive-streak-stage chick blastoderms was partially removed. This experiment provokes a reaction in the epiblast which curls up and becomes even at its ventral surface. The basal lamina underlying the epiblast is also dependent upon the presence of hypoblast. During culture after partial hypoblast removal, active hypoblast wound healing is observed. Where the hypoblast underlies the epiblast again, the effects of the removal disappear and normal development proceeds. The results suggest that the normal epiblast morphology is dependent upon the presence of hypoblast. This influence of hypoblast on epiblast is thought to be concerned with the morphology of the epiblast and not directly with its morphogenesis.