DEVELOPMENT AND SECRETORY FUNCTION OF NEUROSECRETORY-A CELL IN BRAIN OF BOMBYX-MORI

Histological and immunohistochemical observations showed that four pai rs of neurosecretory A cells coincide with the bombyxin neuron which p roduces the 4K-prothoracicotropic hormone (4K-PTTH). The A cells are c haracterized by a large cytoplasmic vacuole containing homogeneous gra nular materials, but the vacuole does not contain the bombyxin. Bombyx in axons from the A cells are distributed on the surface of the corpus allatum (CA), and neurosecretory granules (NSGs) are released by exoc ytosis at earlier stages than those in other neurosecretory axons (NSA s). Embryonic bombyxin neurons show characteristics of secretory funct ion after the bristle formation stage (156 h after egg laying) and bec ome the neurosecretory A cells in the larval stage. (C) 1996 Wiley-Lis s, Inc.