Development of the suboesophageal body during embryogenesis without diapause in Locusta migratoria (linnaeus) (Orthoptera: Acrididae)

The development and the ultrastructural changes of the suboesophageal body were studied during embryogenesis of Locusta migratoria (Orthoptera : Acrididae). The suboesophageal body develops from the mandibular coelomic cavities. It differentiates early, before the completion of germ band segmentation (stage IIIc), the other mesodermal cells remaining undifferentiated. The cells of the suboesophageal body rapidly develop a structure similar to that of nephrocytes. They consist of a peripheral transfer zone and a perinuclear zone, the site of synthesis and storage. Material absorbed by endocytosis is taken up by α-vacuoles, then stored in β-vacuoles. Golgi vesicles, tubules and vesicle complexes may be involved in the secretory activity of the cells. The activity of the suboesophageal body is maximal until stage VI, after katatrepsis, after which degeneration begins. Very few cells remain at eclosion and they are completely degenerated. The suboesophageal body may be involved in the regulation of embryonic haemolymph composition, and it develops according to its function. The suboesophageal body differentiates early and is thus functional when the haemolymph first forms in the subgerminative space. It degenerates after the differentiation of the pericardial cells and the fat body, which regulate haemolymph composition.