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Light and electron microscopic analysis of synaptic development in Macaca monkey retina as detected by immunocytochemical labeling for the synaptic vesicle protein, SV2
Author(s) -
Okada M.,
Erickson A.,
Hendrickson A.
Publication year - 1994
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.903390406
Subject(s) - foveal , retina , synaptogenesis , ribbon synapse , neuroscience , biology , synaptic vesicle , outer plexiform layer , retinal , inner plexiform layer , amacrine cell , immunocytochemistry , anatomy , vesicle , biochemistry , genetics , membrane , endocrinology
The development of synapses has been followed in Macaca monkey fetal and infant retina using immunocytochemical labeling for the transmembrane synaptic vesicle glycoprotein, SV2. Electron microscopy (EM) was used to verify the presence of morphological synapses at selected ages. EM immunocytochemical labeling in adult retina showed that all synaptic types contained SV2 in inner (IPL) and outer (OPL) plexiform layers. In fetal retina, SV2 expression and the appearance of morphological synapses were closely related in time, demonstrating that SV2 is a reliable marker for synaptogenesis. SV2 expression appears along a foveal to peripheral gradient. Both SV2 and synapses appear in the foveal IPL at Fd50–55, and reach the retinal edge by Fd90–103. Cone ribbon synapses and SV2 labeling are not present in the foveal OPL until Fd60. Photoreceptors in the far periphery contain SV2 by Fd119–125. This pattern demonstrates an “inner to outer” direction of synaptogenesis. Cones show SV2 labeling before rods at the same retinal eccentricity. In the cone‐dominated fovea, SV2 labeling and bipolar cell ribbon‐containing terminals are present at Fd55 when amacrine cell conventional terminals are very scarce, indicating that bipolar synapses precede amacrine synapses in monkey foveal IPL. SV2 labeling and bipolar terminals appear first in the outer IPL which contains “OFF” ganglion and bipolar processes in the adult, suggesting that “OFF” midget bipolar cells may form the first synapses. Both SV2 immunocytochemical labeling and EM morphology find that monkey retina follows a generalized inner before outer, and cone before rod synaptic developmental pattern, similar to that in other mammals. The cone‐dominated fovea initiates synaptogenesis, and shows a different synaptic sequence from rod‐dominated peripheral retina. © 1994 Wiley‐Liss, Inc.