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 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/mm2 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 microns. 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 less than = 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.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
