Egg-jelly production and composition in an oviparous chondrichthyan,Scyliorhinus canicula(Linnaeus, 1758)

Embryos of oviparous chondrichthyans develop within a structurally complex tertiary egg envelope known as the egg-case, which is provisioned with a secondary egg coat known as the egg-jelly. Whereas the former has been studied in detail, relatively little attention has been paid to the latter. This study examined the production and composition of egg-jelly in the small-spotted catsharkScyliorhinus canicula(Linnaeus, 1758) and determined that it is a mucin hydrogel. The role of the egg-jelly appears to be one of simple, physical support for the developing embryo, as it was not found to possess bactericidal properties, nor did its constituents suggest a nutritive role.