Distribution and organization of the nerve fiber and ganglion cells of the human choroid

Abstract

Antibodies to the 68, 160 and 200 kD of the neurofilament triplets were used to study the distribution and organization of neuronal structures in the human choroid. Choroidal axons were observed in the suprachoroid and vascular laminae but absent from the choriocapillary layer. Most axons were situated in the suprachoroid. In this layer, there were band-like bundles. The two thickest band-like bundles could constitute the long ciliary nerve, while the rest could constitute short ciliary nerves. These bundles ran through the suprachoroid, branching out on the suprachoroid and the vascular laminae until they reached the ciliary body. In the submacular area of the suprachoroid, the branches of the band-like bundles were so intermingled that they looked like a meshwork. In the vascular layer, the large vessels and their primary branches were accompanied by paravascular axons. Some paravascular axons penetrated the medium-caliber vessel layer and in the submacular area interwove to form a network parallel to the arteriole walls. In addition, perivascular axons were revealed by antibodies to neuropeptides. Choroidal ganglion cells were more numerous in the central choroid, specifically in a circumferential area corresponding to the entrance of the short posterior ciliary arteries and their primary branches, and in the vicinity of the submacular area. These cells presented bipolar and multipolar morphology. The high concentration of innervation in the central human choroid could be necessary to maintain strict blood flow in this zone; thus if required, these neuron structures could induce early vasodilation reflexes at the entrance of the choroidal blood vessels to increase the blood flow.

Choroidal Vessel Wall: Hypercholesterolaemia-Induced Dysfunction and Potential Role of Statins

“…In addition to the nerve fibres, the choroid has intrinsic choroidal neurons (ICNs). Both nervous structures are more abundant in the suprachoroid than in the rest of the vascular layers, with no innervation in the choriocapillaris [20].…”

“…1A). It is composed of tightly packed collagen fibres, melanocytes [14], fibroblasts [15], elastic fibres [16], smooth-muscle cells [16][17][18], nerve plexus, and intrinsic choroidal neurons (ICNs) [19][20][21]. In primates, birds, and rabbits, this layer contains large, endothelium-lined spaces, which empty into veins.…”

“…The sympathetic fibres are from the superior cervical ganglion, the parasympathetic from the ciliary and pterygopalatine ganglion, and the sensitive fibres from the trigeminal ganglion. These nerve fibres reach the choroid in three ways: i) going around the SPCA, these fibres stem from the plexuses of the internal carotid and continue with the ophthalmic artery until reaching the SPCA in the choroid; ii) through the short posterior ciliary nerves that stem from the ciliary ganglion; or iii) through the long posterior ciliary nerves that come from the nasociliary nerve [19,20] (Figure 6). In addition to the nerve fibres, the choroid has intrinsic choroidal neurons (ICNs).…”

“…They head towards the anterior part of the eyeball, with few branches in the part towards the suprachoroid or the choroidal vessel layers [20] (Figure 6). The short ciliary nerves enter the choroid together with the SPCA around the optic nerve and proceed towards the ciliary body.…”

“…The short ciliary nerves enter the choroid together with the SPCA around the optic nerve and proceed towards the ciliary body. In this trajectory, there are many branches for the suprachoroid and the choroidal vessel layers [20] (Figure 6). …”