The suspensory apparatus of the canine lens

The suspensory apparatus of the canine lens was studied in gross specimens stained with periodic acid and Schiff's reagent, and by transmission and scanning electron microscopy. Two distinct groupings of zonular fibres were discernible: those passing along the crests of the ciliary processes and inserting at the lens anterior to the equator, and those arising from the walls of the ciliary processes and inserting posteriorly at the lens. In addition, zonular fibres were found to arise from single plicae and from processes of intermediate size located between the main ciliary processes. The vitreous body was firmly attached to the pars plana, over which zonular fibres passed in a meridional direction, and also to the lens capsule adjacent to the posterior zonular insertions. The mode of insertion of the zonular fibres at the lens and over the unpigmented ciliary epithelium is described. Zonular fibrils averaged approximately 13 nm in diameter, with a periodicity of 17 nm and were morphologically similar to those of other species.