Electron microscopic observation on the developing rabbit and human vitreous collagen fibrils by negative staining.

The vitreous fibrils of developing eyes of 3-day-old rabbits and 24th week human fetuses were examined by the negative staining method (phosphotungstic acid) electron microscopically. Fibrils about 10 nm in diameter and with no periodic striated pattern as well as adult ones were observed. Peculiar fibers were observed in both vitreous samples preserved at low temperature. Particularly, dimeric segment-long-spacing (SLS) aggregates and fibrous-long-spacing (FLS)-like aggregates were observed in 3-day-old rabbit vitreous. FLS-like aggregates showed a 125-nm light band and 50-nm dark band periodic pattern and seemed to be formed with 300-nm overlapping of dimeric SLS aggregates. The present results indicate that the developing vitreous could possibly form various types of collagen fiber under native conditions.