The innervation of the mystacial pad of the rat as revealed by PGP 9.5 immunofluorescence

Abstract

The innervation of the mystacial pad in the rat was investigated with the aid of antihuman protein gene product (PGP) 9.5 immunofluorescence. PGP 9.5 is ubiquitin carboxyl-terminal hydrolase, which is distributed throughout neuronal cytoplasm. This technique revealed all previously known innervation as well as a wide variety of small-caliber axons and some endings of large-caliber afferents that had not been observed before. Newly revealed innervation affiliated with vibrissal-follicle sinus complexes included 1) fine-caliber, radially oriented processes in the epidermal rete ridge collar; 2) a loose network of fine-caliber, circumferentially arrayed processes in the centrifugal part of the mesenchymal sheath at the level of the ring sinus; 3) a loose haphazard network of fine-caliber and medium-caliber processes in the mesenchymal sheath and among the trabeculae of the cavernous sinus; 4) a loose network of circumferentially arrayed processes within the mesenchymal sheath of the cavernous sinus and in close proximity to the basement membrane; 5) a dense network of reticular-like endings provided by large-caliber afferents to the mesenchymal sheath in the upper part of the cavernous sinus; and 6) fine-caliber innervation to the dermal papilla at the base of all vibrissal shafts. In the intervibrissal skin, a dense distribution of fine-caliber individual and clustered profiles was detected in the epidermis. In addition to previously known innervation, Merkel endings were consistently observed in the epidermis at the mouths of guard hairs, loose networks of fine-caliber axons were found around the necks of occasional guard hairs, and fine-caliber profiles were frequently affiliated with vellus hairs. Vascular profiles were heavily innervated throughout the dermis. Axons and motor end plates of the facial nerve innervation to papillary muscles also were labeled. Transection of the infraorbital nerve eliminated all but the facial nerve innervation. Unilateral removal of the superior cervical ganglion eliminated the innervation to the dermal papillae but caused no other noticeable reduction. PGP 9.5-like immunofluorescence was also moderately expressed in apparent Schwann cells, in Merkel cells only in the external root sheath of vibrissal follicles, and in apparent dendritic and/or Langerhans cells usually located in the epidermis and occasionally in the follicles. PGP 9.5-like immunofluorescence persisted in highly vacuolated profiles along the usual courses of medium to large-caliber axons 2 weeks after nerve transection. The possible functional role of the newly discovered innervation is considered along with that of previously identified afferents.

Paclitaxel- and vincristine-evoked painful peripheral neuropathies: Loss of epidermal innervation and activation of Langerhans cells

“…LCs have close appositions with IENF terminals (Rice et al, 1993;Gaudillere et al, 1996;Hsieh et al, 1996). LCs express inducible nitric oxide synthase and release NO (Qureshi et al, 1996), which might sensitize remnant nociceptors.…”

Target-derived BMP signaling limits sensory neuron number and the extent of peripheral innervation in vivo

“…As shown schematically in Fig. 5, based on previous studies (Fundin et al, 1997b;Rice et al, 1998;Rice et al, 1997;Rice et al, 1993), the inter-whisker fur is supplied by a dermal plexus composed of small nerves that are distributed into four distinct tiers oriented parallel to the skin surface.…”

Transport and Localization of the DEG/ENaC Ion Channel BNaC1α to Peripheral Mechanosensory Terminals of Dorsal Root Ganglia Neurons

“…Hair follicles are innervated by fibers that either wrap around the follicle (circumferential endings) or encircle the follicle with comb-like terminals (palisade endings); these correspond to rap- idly adapting mechanoreceptor neurons (Sinclair, 1982;Millard and Woolf, 1988;Rice et al, 1993). BNaC1␣ localizes to both circumferential and palisade terminals of follicles from different areas of hairy skin, such as the furry skin of the rat snout and the less hairy skin of the dorsal side of the mouse paw (Fig.…”