Electron microscopic studies on zonular fibers. II. Changes of the zonular fibers after the treatment with collagenase, alpha-chymotrypsin and hyaluronidase.

Adult rabbit zonular fibers maintained in their native condition were treated with collagenase, alpha-chymotrypsin and hyaluronidase, and were observed with the electron microscope. The results obtained were as follows: 1. Collagenase digested the lens capsule, but not the zonular fibers. 2. Long time collagenase action obscured the cell membrane of the lens epithelium and the basal lamina of the ciliary epithelium. 3. Washing with 0.9% NaCl increased the collagenase action on the lens capsule. 4. Alpha-chymotrypsin digested the zonular fibers and the zonular lemalla, but not the lens capsule and the basal lamina of the ciliary epithelium. 5, Hyaluronidase only slightly changed the lens capsule. 6. The vitreous fibers were digested by collagenase, but not by alpha-chymotrypsin or hyaluronidase. Thes results together with the review of recent literature indicate that the zonular fiber has a nature close to that of the microfibril of elastic fiber.