ウナギの初期発生について

概要

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Eggs and milt used in this study were obtained from the male matured by the treatment with Synahorin and the female injected with salmon pituitary. And they were fertilized by the dry method and kept in normal sea water at 23°C. 1) Fertilized eggs of about 1.0mm in diameter were pelagic and showed a typical discoidal cleavage. Morula blastoderm were formed about 3 hours after insemination. Eggs in the blastula stage were seen about 5 hours later and showed a clear blastocoel. Gastrulation occurred about 91/2 hours after. When the blastoderm covered 1/3 yolk, an embryonic shield became clear. Thereafter, the embryonic body began to form, and the blastopore stage was completed 24 hours after fertiliza-tion. At that time the head and 10 somites were differentiated in the embryo. 2) Eye vesicles and ear vesicles were formed in the embryo 25 hours after, and the heart and 30 somites were discernible in the embryo 28 hours old. Then, the heart commenced pulse and an embryonic tail arrived at the ear vesicle region. Hatching began about 38 hours after. The embryos just after hatching measured 2.9mm in total length and had a large yolk sac. They had 40 somites. Very few pigments were recognizable only at the caudal region of the embryo.
日本水産學會の論文