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Electron microscopic study of immunocytochemically labeled centrifugal fibers in the goldfish retina
Author(s) -
Kawamata Kunihiko,
Ohtsuka Teruya,
Stell William K.
Publication year - 1990
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.902930410
Subject(s) - retina , biophysics , biology , fmrfamide , inner plexiform layer , electron microscope , axon , retinal , anatomy , outer plexiform layer , axon terminal , fiber , materials science , neuropeptide , optics , neuroscience , biochemistry , physics , receptor , composite material
The centrifugal fibers innervating the goldfish retina were studied quantitatively by light and electron microscopy. These fibers originating from cell bodies in the olfactory bulb were labeled by antiserum to the tetrapeptide Phe‐Met‐Arg‐Phe‐NH 2 (FMRFamide). The number of FMRFamide‐immunoreactive (ir) centrifugal fibers in each eye of the adult goldfish (body length: 12‐15 cm) was 65 + 14 (mean ± S. D., n = 7). All of these fibers in the optic nerve and the retina were unmyelinated. Each FMRFamide‐ir centrifugal fiber runs along the optic fiber layer and gives several terminal arborizations in the outermost layer (layer 1) of the inner plexiform layer. Layer 1 is, therefore, densely covered by a plexus of terminal arborizations. Along these terminal arborizations, we found output synapses characterized by a cluster of small clear vesicles (40 nm in diameter) at the presynaptic site and a thickened membrane in the apposed retinal cell processes. In a sample area of 2,000 üm 2 , such synapses occurred at a density of one per 105 üm 2 , or about 13,000 per centrifugal fiber. Thus, the FMRFamide‐ir centrifugal fibers are likely to modulate retinal cell activity through an estimated total of 840,000 output synapses per retina.