FINE STRUCTURE OF MICROPYLAR REGION DURING OOGENESIS IN THE HAGFISH, EPTATRETUS BURGERI (CYCLOSTOMATA)

摘要

Ultrastructure of micropylar region during egg development in the Japanese hagfish, Eptatretus burgeri, was investigated. The micropyle was formed by invasion of piling micropylar cells through the chorion toward a pit of the egg surface. The cells were surrounded by streaked layer in the pit, however, by amorphous material in other regions until late stages of the oogenesis. These features are different from the features in the teleost. Relation between the egg and the sperm in low vertebrates was also discussed.