Figure 1

Autonomic innervation of skin arterioles. Leg autonomic innervation disclosed by confocal microscope (x600 in A and x400 in B and C). (A) Adrenergic fibers disclosed by a staining against TH (red) and NPY (green). They run longitudinally to the main axis of the vessel often clinging to it forming a mesh-like network. These fibers likely presented a vasoconstrictor activity considering the close and enveloping relationship with the vessel wall. A few fibers are stained by TH and VIP (blue; arrow) but not by NPY. They are likely to be sympathetic cholinergic fibers (see also C). These latter run close to adrenergic NPY fibers suggesting a coordinated functional activity. The strict correlation between sympathetic cholinergic and adrenergic fibers is showed in a high magnification image (#); (B). Around skin arterioles a few non-adrenergic fibers expressing peptidergic markers are found with a likely somatic function. In such arterioles a fiber selectively stained CGRP (blue) without TH (green) and NPY (red) staining is showed by the arrow. (C) Sympathetic cholinergic fibers (arrows) were stained by TH (blue), VIP (green) and VACHT (red) more clearly reported in the high resolution image (#). By contrast fibers stained only by TH were adrenergic (asterisks). A few VIP and VACT positive fibers were not stained by TH staining, which makes it likely that they represent parasympathetic fibers (head of arrow) better reported in the high resolution image (#).