Ultrastructure of the basiepithelial nerve plexus of the sea urchin, Centrostephanus longispinus.

The basiepithelial nerve plexus of the Echinoid, Centrostephanus longispinus, contains strands of nerve fibres, which measure between 0.1 and 2.0 mum -in diameter. Nonciliated epithelial supporting cells do not contribute to the plexus. Within the fibres different cesicular inclusions are found. By means of serial sectioning the structure of multipolar cell bodies within the plexus could be demonstrated.