Cotesia kariyai teratocytes: growth and development.

The growth and development of teratocytes was examined in the Cotesia kariyai-Pseudaletia separata system. Cotesia kariyai embryos released an average of 163 teratocytes at the time of hatching, 3.5 days after oviposition. The cells increased in diameter from 30 to 77 µm until 7 days post-parasitization, after which there was no significant increase in average diameter. However, there was significant variation in diameter within the population of teratocytes during the later developmental stages of the parasitoid larvae. The DNA contents increased up to day 7. The ploidy level of teratocytes increased 4-fold (2C to 8C) from days 4 to 7 and thereafter remained the same. Scanning electron microscopy (SEM) revealed that the surface of the teratocytes was covered with microvilli during all developmental stages, although on days 9 to 10 post-parasitization, bleb structures were also observed on a few. In vitro analysis of the proteins secreted from teratocytes following labeling with (35)S-methionine showed that many proteins were synthesized de novo and secreted by the cells until 9 to 10 days post-parasitization. These results indicate that teratocytes in later stages of development maintain their activity and regulate the physiological state of the host.