The fate of vitellogenin, vitellogenic female-specific protein, during embryogenesis in the German cockroach was investigated by an immunofluorescent technique. The period of the embryonic development of this insect is about 25 days at 25 ± 1°C, and it has been divided into 18 stages (Tanaka, 1976).
Vitellogenin-specific fluorescence was evenly distributed among yolk spheres until stage 4. The intensity of the fluorescence of each yolk sphere, however, began to be uneven at stage 5, and the unevenness became more distinct in stages 6–7 to reach a mosaic appearance with respect to fluorescence. After stage 8, the mosaic appearance disappeared, and the intensity of fluorescence of the yolk region decreased on the whole as the stage advanced.
In vitellophages, no specific fluorescence was observed until stage 6. Very strong fluorescence, however, became observable in some vitellophages at stage 7. All vitellophages became fluorescent after stage 8. Some vitellophages, however, lost the fluorescence after stage 12, though the strong fluorescence still persisted in others until a fairly late stage when the cells became shrunken.
The specific fluorescence was observed in the yolk region only until stage 10. The nuclei of the body region of the embryo, however, began to fluoresce very strongly at stage 11 when dorsal closure had occurred. It persisted during stages 11–13, and abruptly declined after stage 14. The cytoplasm of the body region also had comparatively weak fluorescence at these stages. In the appendageal region including the antennae and pleuropodia, the specific fluorescence was not observed at all either in the nuclei or cytoplasm during development.
The Female-specific Protein (Vitellogenic Protein) in Crustacea with Particular Reference toOrchestic gammarella(Amphipoda)
