Actinlike filaments in the neurosecretory cells of Helisoma duryi (Gastropoda, Pulmonata)

Abstract

The mediodorsal neurosecretory cells in the cerebral ganglia of Helisoma duryi send axons into the median lip nerve, where they terminate to form a probable neurohaemal area. After glycerination these cells are shown to contain a branching network of 5- to 6-nm diameter filaments, which are abundant throughout the axon and axon ending but less prominent in the perikaryon. The filaments react with heavy meromyosin subfraction SI, increasing in thickness and forming arrowhead-shaped complexes; the reaction is reversed by adenosine 5′-triphosphate (ATP). This reaction indicates that the filaments contain actin, and it is suggested that actin–myosin interactions could be responsible for neurosecretory granule transport along the axon.