Quantitative Analysis on the Distribution of Collagen Fibril Diameters in the Neural Sheath of Sepia Officinalis

Abstract

In vertebrates, considerable variation in collagen fibril diameters has been reported depending upon species, tissue, age and mechanical requirements (Parry et al., 1978). Rat-tail tendon, for instance, has been shown to have a unimodal distribution of collagen fibril diameters at birth, but a bimodal distribution from a time shortly after birth through maturity to senescence (Parry and Craig, 1977). In invertebrates, however, although connective tissues have been extensively studied by electron microscopy, to date no quantification has been carried out on their components, and particularly on collagen fibrils. The purpose of this investigation was to carry out a statistical analysis on the diameters of collagen fibrils in the neural sheaths enveloping stellate ganglia of Sepia officinalis, and to verify the existence of a correlation between fibril diameters and animal body size. The stellate ganglion, which can be easily removed from the inner side of the cuttlefish mantle, was chosen because it possesses a well developed connective tissue sheath whose collagen fibrils are probably less influenced by mechanical factors than, for instance, those in the mantle.