Figure 3

Sympathetic innervation of a sweat gland. Sympathetic innervation of a sweat gland disclosed by a confocal microscope analysis (x600 in A and x400 in B). (A) Cholinergic VACHT positive fibers (red) encircling sweat gland tubules. These fibers did not show a staining against DbH (although occasionally adrenergic fibers could be found around sweat tubules). The majority of these fibers co-expressed CGRP (blue) indicated by head of arrows as more clearly reported in the high resolution image (#). A few CGRP fibers that did not express VACHT (arrows) probably represent somatic fibers enlarged in the high magnification image (#). (B) However, the majority of sudomotor fibers are sympathetic cholinergic showing TH (blue) and VACHT (red), VIP (green) positive staining (arrows) as showed clearly showed in the high resolution image (#). These fibers encircle sweat tubules with a sudomotor activity. TH staining is less intense than sympathetic adrenergic fibers of a skin arteriole (asterisk) close to the sweat gland. In addition, the VIP and VACHT staining of the arteriole shows an interrupted staining with varicosities located at regular intervals along the nerve fiber. This is slightly different from the VIP and VACHT staining found around the sweat gland characterized by a more regular signal. These divergences may probably indicate a different concentration of the molecular machine needed for the cholinergic transmission with higher concentration in the sudomotor fibers.