Development of the subsoephageal body cells and the pericardiac cells during embryogenesis with diapause in Locusta migratoria (Linnaeus 1758) (Orthoptera: Acrididae)

During Locusta migratoria embryogenesis, the yolk is progressively degraded and the resulting metabolites are released in the haemolymph. We researched the organs possibly involved in the uptake of haemolymphatic proteins. Among organs originated from mesoderm, the SOB (suboesophageal bodies) situated in the embryonic head are remarkable by a very early acquisition of differentiated cytological characters, while most other cells of the embryo are undifferentiated. The SOB quite disappear before hatching. Just before katatrepsis stage, the other organs derived from mesoderm begin to differentiate, including the PC (pericardial cells) which take over from the SOB. These cells, situated in thorax and abdomen, are developed during the dorsal close of embryo. The development and the ultrastructural changes of the SOB cells and of the PC were studied during an embryogenesis with diapause. The morphology of embryos which enter diapause is comparable with that of a continuous development at the beginning of katatrepsis. However, the cells of SOB and PC cells suffer from remarkable changes not only physiologically but cytologically. At the beginning of diapause, the proteosynthetic activity practically disappears in the SOB cells and the lysis areas appear. Nevertheless, the exchanges between these cells and the haemolymph still remain important. For the period of cold, which is necessary to the resumption of development, the aspect of the SOB cells changes and in particular the areas of lysis become less wide. When the embryo reopens its development, the SOB cells show a proteosynthetic activity and the areas of lysis disappear. The changes of the SOB cells and of the PC cells are regularized during the resumption of the development: the SOB cells which had again taken a normal activity start to regress from the stage VII on, while the PC cells take over.