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Fine structure of the optic fiber termination layer in the tectum of the teleost Rutilus : A stereological and morphometric study
Author(s) -
Peyrichoux J.,
Pierre J.,
Repérant J.,
Rio J. P.
Publication year - 1986
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.902460306
Subject(s) - biology , synaptic vesicle , vesicle , retinal , anatomy , electron microscope , retina , ultrastructure , biophysics , neuroscience , biochemistry , physics , membrane , optics
The stratum fibrosum et griseum superficial. (SFGS) of the Rutilus optic tectum, which receives a massive fiber from the projection from the contralateral retina, was studied by electron microscopy The qualitative and quantitative analysis of the laterodorsal (LD) portion of the stratum involved both a stereological examination of the different elements and a morphometric study of the various profiles containing synaptic vesicles (PCSVs). The relative volume of each element in the LD SFGS was as follows: myelinated and unmyelinated axons, 6.6%; PCSVs, 38%; dendrites without vesicles, spines, and cell bodies, 41.7%; glia, 10.5%. With the fixation employed, 35% of PCSVs showed spheroidal synaptic vesicles. These profiles could be subdivided into three types: (1) S1 (23.5%) represented optic terminals, since they degenerated after retinal ablation or were labeled after intraocular injection of HEP or [ 3 H] proline. Three subgroups of S1 were identified: Slm‐profiles containing clear mitochondria;Sli‐isolated profiles that were contiguous with S1m and lacked mitochondria;Sli‐isolated profiles without mitochondria. (2)S2(9.3%) were characterised mainly by their dark mitochondria.(3)S3 (2.2%) corresponded to small nonvisual terminals that were isolated and lacked mitochondria. The PCSVs with pleiomorphic synaptic vesicles (65%) were subdivided into three groups: P1 (38%), P2 (19%), and P3 (8%). P1 and P2 were axonal in nature; P2 could be distinguished from P1 by a greater density of synaptic vesicles. P3 was of dendritic origin. Analysis of synaptic patterns revealed a small number of serial synapses. The presynaptic elements were optic boutons, whereas the intermediate profiles were dendrites with synaptic vesicles (P3). Results are compared with ultrastructural data obtained in the superficial tectal layers of other teleosts and other vertebrate groups.