Immunohistochemical study of rabbit choroidal innervation

lImmunocytochemical methods with antibodies to the light (68 kDa), medium ( 160 kDa), and heavy (200 kDa) chain subunits of the neurofilament triplet h ave been used to visualize neuronal structures in rabbit choroids. Choroida l nerve fibers were present in the suprachoroid and vascular laminae and ab sent in the choriocapillary layer. These fibers may be classified as periva scular and intervascular. Perivascular fibers surround all arterial and ven ous blood vessels and form a network; these fibers were labeled with the th ree NF antibodies, although they were more easily visualized with anti NF-1 60 and anti NF-200 than anti NF-68. Intervascular fibers formed two groups. The first group consisted of fibers situated between the blood vessels and parallel to the blood vessel wall surface (paravascular fibers); these fib ers were better observed using anti NF-160 and NF-200 than anti NF-68. The second group consisted of fibers which travel the entire length of the chor oid until they reach the nerve plexus of the ciliary body (long tract fiber s). The plexus was observed with anti NF-68, anti NF-160 and anti NF-200; h owever, the long tract fibers were more clearly visualized with anti NF-160 and anti NF-200 than with anti NF-68. Two types of choroidal cell were als o labeled: ganglion cells and melanocytes. Ganglion cells are small, scarce neurons situated in the peripheral choroid; they were labeled with anti NF -160 and anti NF-200. The melanocytes were only labeled with anti NF-200 an d they were the only non neuronal structure visualized using antibodies aga inst neurofilaments. (C) 1999 Elsevier Science Ltd. All rights reserved.