[Synaptophysin in the nervous system and endocrine cells]

Synaptophysin is a major integral membrane glycoprotein of neuronal synaptic vesicles that is present in virtually all synapses and shows a high degree of evolutionary conservation in mammalian species. It has also been detected in numerous endocrine cell types where it is localized in the membrane of small synaptic-like vesicles which are thought to constitute a previously unknown secretory pathway. Antibodies directed against synaptophysin are a valuable tool for the immunohistochemical quantitation of synapses. Moreover, synaptophysin is a most reliable and specific marker molecule for normal and neoplastic neuroendocrine cells. In the nervous system, synaptophysin-positive tumors comprise ganglioneuromas, ganglioneuroblastomas, neuroblastomas, paragangliomas and primitive neuroectodermal tumors.