Electron-microscopic study on the fibrillar network and fibrocyte--collagen interactions in the vitreous cortex at the ora serrata of human eyes with special regard to the role of disintegrating cells.

The diameter of the fibrils in the normal vitreous cortex at the ora serrata of human eyes was found to range from 10.8 to 12.4 nm. There is no significant increase in thickness with age. Periodic cross-striation typical for collagen could be demonstrated by microdensitometry. In senile eyes, secondary lateral aggregations of the fibrils are a common factor, usually in proximity to disintegrating cells. Disintegrating cells in the vitreous cortex were already observable in childhood. They were more often seen with increasing age. In a pathological case, acid phosphatase could be demonstrated both within the vitreous fibrocytes and in the extracellular space, released from disintegrating cells. Fibrils and segments of banded material were observed within pits and invaginations, and in intracytoplasmic channels and vacuoles of the aged vitreous fibrocytes. Linear aggregations of ruthenium red-positive material were seen at the surface and within invaginations of the same cells. The findings are interpreted as an indication for phagocytosis and--or secretion of collagen by the vitreous fibrocytes even in senile eyes.