[Ultrastructural, immunohistochemical and immunoelectron microscopic studies on the transitional part of the trabecular meshwork and the ciliary muscle in human and porcine eyes].

The authors demonstrated the ultrastructure of the transitional portion of the human trabecular meshwork (TM) of the ciliary muscle (CM) by transmission electron microscopy, together with the porcine TM and CM, which have not been reported so far. In the transitional portion of the human eye, bundles of smooth muscle cells showed tapering in the anterior portion, and long slender processes of TM cells covered the outside of muscle bundles occasionally, in association with intervening nerve fibers. In the human transitional portion, there were many stick-like or irregular-shaped structures consisted of collagen fibrils. In the porcine eye, although the fine structure of the TM was similar to that of human TM, the shape of each porcine CM cell was irregular and their cytoplasm were invaginated into the adjoining cells, like herniation. In the immunohistochemical study, the positive immunoreactions were found in TM cells for vimentin, Schwann cells for S-100 and S-100b, and the CM cells for muscle (m)-actin and desmin in both species by using each antibody. Only the porcine TM cells were positive for S-100 and S-100b. In the human eye, smooth muscle-like cells similar to TM cells in the transitional portion were detected, and these cells were positive for m-actin. Moreover, the cells covering Schlemm's canal were positive for factor VIII and UEA-1. These immune positivities were confirmed at the ultrastructural level. These immunohistochemical reactions may be useful tools to evaluate cell at the light and electron microscopic levels in human and porcine TM and CM regions.