The structure of the central nervous system of a pulmonate molluse (Cryptomphallus aspersa). I. Ultrastructure of the connective epineural sheath.

Abstract

The connective epineural sheath of the abdominal mass ganglia of the land snail Cryptomphallus aspersa was studied by light and electron microscopy. In this sheath several cellular types were found: fibroblasts, macrophage cells, a special type rich in mitochondria; elongated cells which proved to be muscle cells of paramyosin type and glial cells with dense bodies in close contact with neurosecretory axons. Special attention was paid to the filaments of the muscle cells. Thin and thick ones were found, the last with cross bands with a repeating period of 150 A. These findings are discussed in relation with the physiological role of the epineural connective sheath in metabolic and mechanical functions.