Browsing by Author "CORREA, R"

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    ULTRASTRUCTURE OF CALCITONIN-GENE-RELATED PEPTIDE-IMMUNOREACTIVE, UNMYELINATED AFFERENTS TO THE CAT CAROTID-BODY - A CASE OF VOLUME TRANSMISSION
    (1995) TORREALBA, F; CORREA, R
    To relate the ultrastructure of unmyelinated afferents to the cat carotid body with the known electrophysiological properties of cat chemosensory C-fibers, we took advantage of the fact that the calcitonin gene-related peptide is exclusively present in a population of sparsely branched afferents to the carotid body. They have a morphology identical to the afferents originating from carotid sinus nerve unmyelinated axons. Immunoreactive axons were stained using pre-embedding protocols and horseradish peroxidase-labeled secondary antibody. Labeling was present only in unmyelinated axons and boutons distributed in the interstitial and parenchymal tissue. The varicosities had an average diameter of 0.7 mu m, and contained both small, clear vesicles and larger dense-core vesicles. No labeled axons were ever seen to contact glomus cells, but could be observed as close as 0.2 mu m to a glomus cell, always with an interposed glial process. With a very sensitive protocol, that used tungstate-stabilized tetramethylbenzidine as the chromogen, amorphous deposits of reaction product were often detected in the extracellular space around a labeled bouton.