[Early morphogenetic movements in intact and fragmented eggs ofAcheta domesticus L. (Orthopteroidea) after vital staining].

1. After injection of trypan blue into virgin females ofAcheta domesticus L. a certain percentage of the eggs contain stain. A short pulse of trypan blue offered to growing oocytes of different sizes leads to incorporation of the dye into different concentric yolk layers. 2. Vitally stained eggs develop normally although trypan blue is highly teratogenic in vertebrates. Streaming movements of differently stained material are analysed by time-lapse micrography. Superficial parts of the yolk plasmodium are assembled during two phases of streaming movements ventrally in the region of the germ anlage. The surface streams are matched by extensive shifting of material deep inside the egg plasmodium. Photographs of stained eggs taken before, during and after the movements demonstrate the dynamics of the system (Abb. 6). 3. Investigation of vital stained egg fragments indicates that streaming movements are determined at the onset of cleavage. Control centres or factor regions activating the morphogenetic movements were not detected in the present study.