Immunohistochemical classification and functional morphology of human choroidal ganglion cells.
OBJECTIVE
To characterize human choroidal ganglion cells (CGCs) further, regarding their immunohistochemical and ultrastructural appearance and their pre- and postsynaptic connections.


METHODS
. Choroidal wholemounts and serial sections of human donor eyes were stained with antibodies against neuronal nitric oxide synthase (nNOS), vasoactive intestinal peptide (VIP), tyrosine hydroxylase (TH), vesicular monoaminergic transporter (VMAT)-2, vesicular acetylcholine transporter (VAChT), neuropeptide Y (NPY), substance P (SP), calcitonin gene-related peptide (CGRP), calretinin, galanin, synaptophysin, and alpha-smooth muscle actin. Ultrathin sections of glutaraldehyde-fixed eyes were studied with an electron microscope.


RESULTS
All CGCs stained for nNOS, most for VIP, approximately 45% for calretinin, and only single neurons for NPY and galanin. Ultrastructurally, the CGCs showed an incomplete glial sheath and, in places, showed close contact to surrounding collagen fibrils. The CGCs were in close contact with numerous boutons staining for the different neuronal markers including synaptophysin, nNOS, VIP, NPY, TH, VMAT-2, VAChT, calretinin, and NPY.


CONCLUSIONS
The data indicate a complex integrative function of CGCs. The immunohistochemical and ultrastructural characteristics also indicate that the CGCs may have mechanosensory properties. The complex synaptic information points to a specific regulative CGC function in parallel with ciliary muscle contraction (accommodation). Axons originating from CGCs mainly supply the choroidal vasculature, thus implicating the CGCs as vasodilative neurons, but single CGCs may also innervate other structures such as nonvascular choroidal smooth muscle cells.
May
Christian Albrecht
CA
Department of Anatomy II, Friedrich-Alexander University, Erlangen, Germany. albrecht.may@anatomie2.med.uni-erlangen.de
Neuhuber
Winfried
W
Lütjen-Drecoll
Elke
E
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000032:analysis; D002648:Child; D002829:Choroid / Q000098:blood supply / Q000294:innervation*; D005726:Ganglia, Parasympathetic / Q000166:cytology* / Q000502:physiology*; D006801:Humans; D008856:Microscopy, Fluorescence; D008875:Middle Aged; D009131:Muscle, Smooth, Vascular / Q000294:innervation; D009419:Nerve Tissue Proteins / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052248:Nitric Oxide Synthase Type I; D017729:Presynaptic Terminals / Q000502:physiology; D014660:Vasoactive Intestinal Peptide / Q000378:metabolism
D015415:Biomarkers; D009419:Nerve Tissue Proteins; D014660:Vasoactive Intestinal Peptide; C496320:NOS1 protein, human; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I