1984 年 51 巻 2 号 p. 287-332
The formative processes and transitional changes of the horny teeth of the lamprey (Entosphenus japonicus) were investigated from the viewpoint of comparative embryology. The horny teeth were examined by macroscopic, light and electron microscopic observation. Following results were obtained.
1. Keratohyaline granules appeared in the cells of the spinous layer later than lipid granules. Most of the keratohyaline granules were small and spherical in shape.
2. In the granular layer, the keratohyaline granules became irregular in form. These granules were associated with bundles of tonofilaments and were gradually formed a network.
3. As keratinization progressed, the cells were filled with this network, which contained bundles of filamentous components.
4. Keratohyaline was synthesized and was newly deposited in the area surrounded by the ribosomes or on the surface of the network and tubular structure where the ribosomes were attached.