Abstract
The surface structure of the various areas of the egg-shell in triploid and tetraploid silkworms was observed under a differential interference microscope.
Triploid eggs: The size of the micropylar region was larger and its shape was more irregular than diploid eggs. The surface structure of the central part of the lateral region was principally the same as that of diploid eggs; namely, a unit of the network was enclosed within the projecting boundary and took the shape of a regular or irregular polygon, while small knobs formed the rest in the polygon. However, the size of the polygons was considerably larger and the number of knobs per polygon was much greater than in the diploid eggs. With regard to the respective surface structure of the area surrounding the micropylar region and of the central parts of the dorsal, abdominal and posterior regions, they differed again from the diploid eggs. Especially, the height of the various knobs or the height of the various walls resembling the boundaries in the lateral region was irregular, when the corresponding area was compared to the diploid eggs.
Tetraploid eggs: The surface structure of the central part of the lateral region was almost the same as the triploid eggs, but compared with that of diploid eggs, a considerable difference was seen. However, with regard to the surface structure of other areas, there was no characteristic difference between tetraploid and diploid eggs.
