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: Acridi dae). The suboesophageal body develops from the mandibular coelomic cavitie s. It differentiates early, before the completion of germ band segmentation (stage IIIc), the other mesodermal cells remaining undifferentiated. The c ells of the suboesophageal body rapidly develop a structure similar to that of nephrocytes. They consist of a peripheral transfer zone add a perinucle ar zone, the site of synthesis and storage. Material absorbed by endocytosi s is taken up by alpha-vacuoles, then stored in beta-vacuoles. Golgi vesicl es, tubules and vesicle complexes may be involved in the secretory activity of the cells. The activity of the suboesophageal body is maximal until sta ge VI, after katatrepsis, after which degeneration begins. Very few cells r emain at eclosion and they are completely degenerated. The suboesophageal b ody may be involved in the regulation of embryonic haemolymph composition, and it develops according to its function. The suboesophageal body differen tiates early and is thus functional when the haemolymph first forms in the subgerminative space. It degenerates after the differentiation of the peric ardial cells and the fat body, which regulate haemolymph composition. (C) 1 999 Elsevier Science Ltd. All rights reserved.