Electron microscopical aspects of acid compartments of the ground substance and of collagen in different cases of intravitreal tissue proliferation.

Abstract

It is demonstrated that 'activated' glial cells or NPE cells are capable of producing small collagen fibrils of the vitreous type as well as basal lamina material. In contrast to this MRPE cells produce a different type of collagen, exhibiting a larger periodicity and larger diameters. Granular and fibrillar polyanionic materials are produced by the MRPE cells as well as by proliferating endothelial cells. The latter substances combined with the newly formed collagen of the MRPE cells in regular distances of about 460-480 A. The most characteristic feature of very young vascular buds is a multilaminar basal lamina, which is established long before a vascular lumen is formed. Collagen fibrils are absent in the early stages of neovascularization; however, they are abundant in more advanced stages. These observations may be helpful in situations where a reliable diagnosis in respect to the origin of a certain cell population is impossible because typical cell characteristics are absent or poorly developed.