Vol. 5, Issue 4 (2020)
Organization of the central ganglia in medically important vector snail Radix acuminata (Lamarck 1822) (Mollusca: Gastropoda: Pulmonata)
Author(s): Pande GS, Sherkhane UD
Abstract: Mollusks have long been used as a model for understanding fundamental processes in neuroscience. The freshwater pulmonate snail Radix acuminata (Synonym: Lymnaea acuminata Lamarck, 1822) is one of the commonly distributed snails in freshwater bodies of India. This snail serves as an intermediate host for parasitic trematodes and plays a significant role in the transmission of human schistosomiasis and fascioliasis disease. The purpose of this paper is to provide a histological description of the central nervous system, the topography of central ganglia, and types of neurosecretory cells in the central nervous system (CNS) of R. acuminata. The CNS consists of paired cerebral, pedal, pleural, parietal ganglia and a visceral ganglion. The ganglia in the form of nerve ring were carefully dissected out and preserved. A routine histological process was followed so as to cut tissues into sections followed by staining. Results obtained showed that all the ganglia are covered by an epineural sheath or perineurium. The central core of each ganglion is called neuropil. The neuropil generally lacks in cell bodies except those of scattered neuroglia and connective tissue cells. The cortex area between the core and perineurium, however, is packed with cell bodies of Neurosecretory cells. The outermost cells are usually the largest, and thus visible topographically in the ganglion. Within the inner layer of connective tissue, the nerve cells are arranged with their cell bodies peripherally and their axons running centrally into the neuropil. Two types of neurosecretory cells, type A and type B cells, are found in almost all ganglia.