シャミセンガイ配偶子形成過程の電子顕微鏡的観察

概要

論文の詳細を見る
The processes of spermiogenesis and oogenesis in Lingula unguis were studied with the electron microscope. Immature gonads of males and females are both filled with nutritive cells which contain few cytoplasmic inclusions except for two kinds of large granules. Oocytes or spermatids grow between these nutritive cells which degenerate as maturation proceeds. In spermiogenesis the granules, produced from Golgi bodies or smooth endoplasmic reticulum, associate to form the pre-acrosomal vesicles. Then two pre-acrosomal vesicles fuse into one acrosome, and move to the top of the spermhead during which time the condensation of the nuclear takes place. Highly electrondense ring-structure in the acrosome is characteristic in this species. Sperm-tails are formed on the base of the posterior centriole from the earliest stage of spermiogenesis. In oogenesis three kinds of granules are observed. One is specific to the cortical layer. The other two differ in electron density and are distributed throughout the oocytes. The origin of these granules is obscure, although it seems that the more electrondense granules appear first and the cortical granules later. After the completion of growth, many microvilli appear on the surface of the oocyte forming a vitelline coat with periodic structures.
1973-09-25