Observations on the ultrastructure of equatorial scleral collagen fibrils in sheep eyes

The aim of this study was to investigate collagen fibrils of the equatorial sclera in relation to the age-related changes in eye size in sheep. Sheep eyes (three lamb and three from adult outbred ewes), presumed disease-free, were processed for transmission electron microscopy (TEM) immediately postmortem. Tissue blocks from the equatorial region were sectioned across fibril bundles orientated along the equator. Micrographs including at least 500 fibrils were projected at 22,000× magnification for measures of fibril diameters (FDs). The study concludes that the equatorial sclera is a mixture of rounder versus flatter collagen fiber bundles, the former being more likely to be made up of a mixture of both smaller and larger fibrils, as compared to slightly smaller fibrils.