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Substance P‐immunoreactive neurons in the human retina
Author(s) -
Cuenca Nicolás,
De Juan Joaquín,
Kolb Helga
Publication year - 1995
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.903560402
Subject(s) - retina , biology , plexus , inner plexiform layer , anatomy , axon , substance p , cell type , immunostaining , cell bodies , neuroscience , neuropeptide , immunohistochemistry , central nervous system , cell , biochemistry , genetics , receptor , immunology
Substance P (SP) is a neuropeptide that acts as a neurotransmitter or a neuromodulator in the retina. The aim of this study was to identify the type(s) and the distribution of the SP‐immunoreactive (SP‐IR) cells in the human retina. We have used an antiserum to SP to immunostain neurons in postmortem human retinae. Immunostained retinae were processedwith the avidin‐biotin complex (ABC) to visualize the cells either whole mounted in glycerol or embedded in plastic. Some retinae were also sectioned at 20 μm in order to obtain radial views of stained cells. SP‐IR amacrine cells stain intensely and appear to be of a single type in the human retina. They are large‐field cells with large cell bodies (16 μm diameter) lying in normal or displaced positions on either side of the inner plexiform layer (IPL). Their sturdy, spiny, and appendage‐bearing dendrites stratify in stratum 3 (S3) of the IPL, where many overlapping, fine dendrites intermingle to form a plexus of stained processes. Either cell bodies or primary dendrites emit an “axon‐like” process that, typically, divides into two long, fine processes, which run in opposite directions for hundreds of micrometers in S5 and S3 before disappearing as distinct entities in the stained plexus in S3. Long, fine dendrites also pass from the dendritic plexus to run in S5 and down to the nerve fiber layer to end as large varicosities at blood vessel walls. In addition, fine processes are emitted from the dendritic plexus that runs in S1, and some pass up to the outer plexiform layer (OPL) to run therein for short distances. The SP‐IR amacrine cell has many similaritiesto the thorny, type 2 amacrine cells described from Golgi studies. In addition to the SP‐IR amacrine cells, a presumed ganglion cell type is faintly immunoreactive. Its 20–22 μpm cell body gives rise to a radiate, sparsely branched, widespreading dendritic tree running in S3. Its dendrites and cell body become enveloped by the more intensely SP‐IR processes and boutons from the SP‐IR amacrine cell type. The SP‐IR ganglion cell type most resembles G21 from a Golgi study. © 1995 Wiley‐Liss, Inc.