A scanning electron microscope study of the structure and fertilization of an ascidian egg, Ciona intestinalis

Abstract

Fertilization of the ascidian egg, Ciona intestinalis, is complicated by extravitelline accessory structures. This report describes morphological aspects of these accessory structures, in particular the follicle cell layer, using the scanning electron microscope. It is suggested that interfollicular clefts exist between adjacent follicle cells thereby facilitating the species-specific binding reaction between sperm cells and the chorion.