Development and life cycle of the parthenogenetically activated sea urchin embryo.

A method is reported for inducing parthenogenetic development in eggs of the sea urchin Lytechinus pictus, a species which previously could not be artificially activated. NH4OH or the calcium ionophore A23187 are used as activating agents followed by hypertonic treatment. The ionophore is superior in activating large numbers of unfertilized eggs, whereas NH4OH produces a larger percent of embryos able to undergo gastrulation. Both feeding larvae and urchins arising from these artificially activated eggs are diploid. All individuals in which sex has been identified have been female. The viability of these completely homozygous organisms is low compared to their fertilized counterparts.