Diffusion barriers impeding the flow of solutes to the ciliary body epithelium during immersion fixation of rabbit eyes. Assessment of ultrastructural preservation quality by examination of mitochondrial profiles in the electron microscope.

Various manipulations of rabbit anterior eye segments were carried out during the initial stages of glutaraldehyde fixation in order to assess the contribution made by particular tissues in restricting the flow of solutes to the ciliary body epithelium. Ultrastructural preservation quality was monitored by inspection of mitochondrial profiles. These organelles are structurally extremely sensitive to environmental disturbances, and hence changes in their morphological appearance may be used as an early indication of such adverse conditions. The results indicate that the principal barriers to diffusion are represented by the vitreous, posteriorly, and by the cornea at the anterior face. Since the cortical vitreous is strongly attached to the inner basement membrane of the ciliary epithelium, its removal may cause damage to this layer. A simpler and equally effective means of improving flow of fixative to the ciliary epithelium is to remove the cornea.