FINE STRUCTURE OF EPINEURAL CONNECTIVE TISSUE SHEATH OF SUBESOPHAGEAL GANGLION IN HELIX ASPERSA

The epineural connective tissue sheath investing the subesophageal ganglion of Helix aspersa consists of a superficial region and a deeper region. The superficial region contains masses of globular cells intermingled with smooth muscle cells and nerve fibers all embedded in a connective tissue matrix. The histochemical and fine structural features of the globular cells show seasonal changes. During autumn to winter glycogen accumulates in their cytoplasm; this accumulation is accompanied by the appearance of dense, cytoplasmic globules which fuse together and ultimately form large pools of granular material. All the organelles and cytoplasm are displaced towards the cell periphery. Various cell-membrane invaginations containing dense material are prominent but there is no direct evidence to link these structures with the uptake of metabolites for glycogenesis. In winter there is a concentration of homogeneous, membrane-bound inclusions in the vicinity of the Golgi bodies. It is suggested that these inclusions constitute a lipid store. They decrease in number during summer. The globular cells do not bear any intimate relation to neurons and there is no reason to include these cells in the neuroglia. The muscle cells often weave around the globular cells but there is no direct contact. Nerve fibers innervate at least some of the muscle cells. The connective tissue consists of large and small diameter fibers suggesting that maturation of the fibrous components of the intercellular matrix is taking place in the superficial regions of the epineural sheath. © 1969 Springer-Verlag.