[Structural organization of the chemoreceptor organs in the snail]

Abstract

The data on the neuronal structure of the head tentacles, lips and osphradium in the snail Lymnaea stagnalis L. have been obtained by means of general histological and histochemical methods, impregnation after Golgi, stainings revealing neurosecrete, methods of retrograde horseradish peroxidase and CoCl2 transport. The sensory areas of the organs studied possess all the main components inherent in the chemoreceptory organs. In the head tentacles and lips, 8 types of the primary sensitive neurosecretory receptory cells have been revealed; according to some signs, they are chemo-, photo- and mechanoreceptory elements, the proprioreceptors including. Various forms of neurons have been revealed. In the osphradium, 4 types of the primary sensitive receptory cells, an essential number of neurons and neurosecretory cells have been detected. The latter participate in osmoregulation (yellow-green cells and yellow cells). In the neuropil of the osphradial ganglion, common areas for branching the receptory cell axons and neuronal and neurosecretory cell dendrites have been revealed; that is considered as a possibility of their direct contact.