Survey of Evidence for Neurosecretion in Gastropod Molluscs

Open Access
Publisher Website
Google Scholar
Abstract
In gastropods that have been studied, there is some indication of the presence of neurons with specialized staining properties that are possibly neurosecretory. However, there are no stains specific for neurosecretion, and certain cellular inclusions can simulate secretory products. The presence of elementary neurosecretory granules does not as such determine neurosecretory status since such granules may represent neurotransmitters. Evidence of cyclical secretory activity of so-called neurosecretory neurons is most frequently related to reproductive phenomena, but there are also instances of control of water balance and hibernation. The existence of neurohemal organs within nerves and commissures has been described in several species. So-called neuroglandular complexes have been reported in association with the nervous system. Vesicles incorporated in the central nervous system may be sensory rather than glandular. Some caution is needed in estimating secretory activity of these complexes. Possible non-neural endocrine glands adjacent to the central ganglia have been described. In pulmonates granule-laden fibers are associated with the mediodorsal bodies; however, the nature of the neurosecretomotor or neurosecretory-neuropil control is still unclear, both morphologically and physiologically.