The fine surface architecture of the primate ciliary body with special regard to the pars plana.

The fine surface architecture of the pars plana of the ciliary body was studied by scanning electron microscopy (SEM) in young and adult primate eyes following the removal of zonular fibers by hydrolysis with hydrochloric acid. In the young eye, the internal surface of the pars plana was characterized by a series of meridional ridges and grooves and, in the posterior region, by conspicuous surface invaginations on the ridges. In the adult eye, the meridional ridges in the anterior pars plana were smaller than in the young eyes and in a varying configuration, and the meridional grooves among the ridges were wide. In the mid-pars plana, spine-like architectures were observed leaning parallel to each other toward the lens, along the course of the zonular fibers. In the posterior pars plana, the internal surface exhibited a reticularly multilayered appearance with interstices of various sizes. In incompletely digested specimens, the zonular bundles were found to dissociate into fan-shaped off-shoots, and were observed entering the meridional grooves and the surface invaginations on the ridges. The procedure used in the present study was considered to be highly useful for SEM observation of the surface morphology of the ciliary body.