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Morphology and mosaics of VIP‐like immunoreactive neurons in the retina of the rhesus monkey
Author(s) -
LammerdingKöppel M.,
Thier P.,
Koehler W.
Publication year - 1991
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.903120208
Subject(s) - vasoactive intestinal peptide , inner plexiform layer , biology , retina , inner nuclear layer , amacrine cell , anatomy , retinal , ganglion cell layer , microbiology and biotechnology , neuropeptide , neuroscience , biochemistry , receptor
Abstract Vasoactive intestinal peptide (VIP) is a 28‐amino acid peptide that has been demonstrated to reside in cells (=VIP+ cells) of the retinae of various vertebrate species. In an attempt to study the morphology and distribution of VIP+ cells in the retina of the rhesus monkey in more detail, we subjected VIP+ cells observed in cryostat sections or wholemounts of rhesus monkey retinae to a quantitative analysis. VIP+ cells were found to reside in the innermost row of the inner nuclear layer (INL) and in the ganglion cell layer (GCL) in similar numbers (estimate: 50 cells/mm 2 at 6–10 mm eccentricity each) and only on rare occasions (12% of all VIP+ cells) in varying positions within the inner plexiform layer (IPL). Somata of VIP+ cells were circular and had a mean diameter of 9.1 μm. They gave rise to 1–3 main dendrites, which were usually oriented toward the IPL. Main dendrites ramified widely into thin fibers (dendritic field diameter < = 1 mm), carrying varicose swellings. The fibers that contributed to one and the same plexus of VIP+ fibers preferred the middle third of the IPL, independent of the positions of the parent somata. A quantitative analysis of nearest‐neighbour distances in the retinal wholemount preparation suggested that VIP+ cells in the GCL and in the INL might be distributed according to 2 independent mosaics. A comparison with Golgi‐stained material leads to the tentative equation of VIP+ cells with the “spiny” A12 amacrine cell of Mariani ('90). Whereas the low density and large dendritic field size of VIP+ cells might suggest a more widespread function, the varicose dendritic morphology seems to be more compatible with functionally independent dendritic subunits mediating localized effects.