Studies on the termination of diapause in silkworm eggs dechorioned and cultured in vitro I. In vitro culture in various culture medium

• Published in: The Journal of Sericultural Science of Japan Vol. 43; no. 2; pp. 111 - 118
• Main Authors: OHTSUKI, Yoshiki, KITAZAWA, Toshio
• Format: Journal Article
• Language: English; Japanese
• Published: The Japanese Society of Sericultural Science 28.04.1974
• ISSN: 0037-2455; 1884-796X
• DOI: 10.11416/kontyushigen1930.43.111

Diapause silkworm eggs were kept at 25° and 30°C after deposition, respectively, and cultured in vitro after removing from chorion at various stages of diapause. Culture medium used for experement were G. I. T. C. M. (G solution), a balanced salt solution (S-2 solution), NaCl solutions with various concentrations and liquid paraffine containing neither nutrients nor salts. After 14 days' culture, the eggs were dissected in a NaCl solution and the development of embryos was examined morphologically. The results obtained are as follows: Embryos could resume their growth at any stage of diapause from 2 to 140 days after deposition and developed well in both of the G and S-2 solution. Most of them developed beyond the stage of bristle formation within 14 days' culture and someones reached almost the stage of abdominal pigmentation. These results show that the diapause of silkworm eggs can easily be terminated by in vitro culture irrespective of the age of eggs, that is, the stage of diapause which is a determining factor in the artificial hatching of diapause eggs by chilling. The termination of diapause was observed in NaCl solutions within a considerably wide range of concentration from 0.40 to 0.90%; especially, all the embryos tested showed evident growth at 0.85% and some of them reached the stage of bristle formation. The termination of diapause and the subsequent development of embryos seemed to be better in a little hypotonic NaCl solution than in a hypertonic one. Similar resumption of embryonic growth also was observed in liquid paraffine From these results, it is considered that various ingredients of the G and S-2 solutions are not essential factors for the termination of diapause.