深海鮫フジクジラ胎児の卵黄吸収過程について

Abstract

1. The embryos of the luminous shark, Etmopterus Lucifer J. et SN., are provided with the yolk duct lying between the yolk sac and the duodenum. Yolk may be taken up directly by the gut of embryo during the development through this duct, although it of course is also absorbed through the vitelline capillaries. 2. The internal yolk sac which organized by inflation of the posterior part of the yolk duct, is first established in the abdominal cavity of the embryo measuring approximately 60mm., and is still retained after the external yolk sac has disappeared. 3. The duration of the gestation period of this shark appears to be about one year.