A new method for mechanical dechorionation of ascidian eggs

Pasteur pipets were prepared with constricted tips of such diameter that unfertilized Ciona intestinalis (L.) eggs could be held immobile while their chorions were lanced open with a tungsten needle. Eggs were pretreated with double-strength seawater to increase the space between egg and chorion. Eighty-five percent of the eggs dechorionated in this way developed normally after fertilization in regular seawater.