Reproductive cycle and ultrastructure of yolk development in some echinoderms from the Bergen area, western Norway

This paper collects data on the gonads, ease of fertilization in the laboratory, and breeding season of 32 species of Echinodermata in the Bergen area (western Norway). It also describes the yolk granules in small and large eggs, which are shown to differ in several respects. The small eggs, as a rule, have small yolk granules with a coarse, granular structure, while large eggs have larger yolk granules with a homogeneous, lipid-like appearance or are complex with homogeneous inclusions.