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Immunocytochemical study of nerve fibers containing substance P in the junctional epithelium of rats
Author(s) -
Tanaka T.,
Kido M. A.,
Ibuki T.,
Yamaza T.,
Kondo T.,
Nagata E.
Publication year - 1996
Publication title -
journal of periodontal research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.31
H-Index - 83
eISSN - 1600-0765
pISSN - 0022-3484
DOI - 10.1111/j.1600-0765.1996.tb00483.x
Subject(s) - axoplasm , junctional epithelium , vesicle , horseradish peroxidase , anatomy , connective tissue , ultrastructure , schwann cell , chemistry , gap junction , free nerve ending , substance p , epithelium , cytoplasm , synaptic vesicle , enamel organ , axon , biology , enamel paint , pathology , ameloblast , materials science , membrane , neuropeptide , intracellular , biochemistry , medicine , receptor , enzyme , composite material
Nerve fibers with substance P‐like immunoreactivity (SP‐IR) in the junctional epithelium (JE) of 32‐42‐d‐old rats were examined by both light and electron microscopy using the avidin‐biotin‐peroxidase complex method. The density of nerve fibers with SP‐IR was highest in the middle portion of the JE; however, a few fibers were localized in the coronal portion of the JE and close to the enamel surface. Also, rich innervation was found especially in the basal cell layer of the JE. Unmyelinated axons with SP‐IR in the connective tissue underlying the JE were enveloped by Schwann cells but lost their Schwann cell sheath almost completely in the JE. The axons often formed varicosities with SP‐IR as terminals in various areas of the JE. The terminals contained numerous large granular vesicles, small clear vesicles and a few mitochondria, and were surrounded by the cytoplasmic processes of the junctional epithelial cells. These terminals were sometimes located close to neutrophils in the JE; the minimum gap distance between the terminals and the processes of junctional epithelial cells or neutrophils was about 20 nm. A few terminals with SP‐IR came close to the enamel surface, and the minimal distance between the terminals and the enamel surface was about 5 μm. SP‐IR in the nerve terminals in the JE fixed with 0.1% or 0.25% glutaraldehyde was distributed diffusely in the axoplasm or was confined to the granular vesicles. These findings show that substance P is contained in the large granular vesicles in the nerve terminals, and suggest that these terminals may function as modulators of junctional epithelial cells and neutrophils.