The ciliary body and the suspension of the lens in a monkey (Cercopithecus aethiops). A scanning electron microscopic study.

The zonules of Zinn and their insertion on the ciliary body and the lens in a monkey (Cercopithecus aethiops) have been studied with the scanning electron microscope. The specimens were dissected after drying by the critical point method, and the lens was separated from the ciliary body by simple traction. The pars plana was completely covered by a mat which consisted of meridionally directed zonule-like fibers. Most of these fibers inserted at the base of the posterior end of the ciliary processes, and some of them radiated into the valleys between the processes. About two fibers for each process split off from the mat and became attached to the sides of the processes near their posterior ends. The true zonules spanned from the sides of the processes to the pre- and post-equatorial region of the lens. They were clearly separated into an anterior and a posterior row with no fibers crossing over from one row to the other. Usually four true zonules joined each process, i.e. one zonule of the anterior row and one of the posterior row attached to each side of the single ciliary process.