Mushroom Bodies of Stick and Leaf Insects (phasmatodea: Insecta): Structure and Sources of Formation

It has been established that mushroom bodies of stick insects are formed by Kenyon cells collected in numerous groups of cells the processes of which originally form individual bundles going into the calyx. The majority of such bundles lose their identity already in the cellular layer, and therefore, complex bundles usually enter the calyx. The merging of bundles progresses in the calyx, and even the peduncle keeps a fascicular structure. Only lobes have a classical concentric structure. In the embryonic period, mushroom bodies are formed by two proliferative centers with one neuroblast per center. It is supposed that the neuroblasts of mushroom bodies of stick insects are neuroblasts of type II and that groups of Kenyon cells are generated by intermediate neural progenitors.