The Innervation of Hyperplastic Epidermis in the Mouse: A Light Microscopic Study

Abstract

The innervation of the skin of hairless mice has been studied following induction of epidermal hyperplasia by physical and chemical methods. Physical stimuli comprised ultraviolet irradiation, heat, wounding, and friction. Effective chemicals included benzene, carbon tetrachloride, chloroform, creosote, formaldehyde, hexadecane, hydrobromic acid, sodium lauryl sulfate, and turpentine. Epidermal hyperplasia, however produced, was associated with growth of sensory nerve fibers into the outer part of the epidermis. Following a single 10-min exposure to an ultraviolet sunalmp at 40 cm, the nerves extended into the epidermis within 24 hr and disappeared during the second week as the epidermis reverted to its normal thickness. Repeated irradiation (until tumors appeared) was accompanied by persistent hyperplasia and neural invasion. Of 32 papillomas examined, intraepithelial nerves were found in 28. The presence and location of nerves in the tumor epithelium were related to the incorporation of tactile hair disc epithelium. The hyperplastic regenerative epithelium at the margins of skin ulcers were also invaded by nerves which sometimes followed the migrating epithelium across the ulcer floor. Since the regenerative epithelium was not directly treated, it was concluded that the proliferation of nervous tissue in response to skin injury was the result of the hyperplasia per se, regardless of the method used to produce it.

Hyperinnervation and Mast Cell Activation May Be Used as Histopathologic Diagnostic Criteria for Vulvar Vestibulitis

“…The relief obtained in many women with vestibulitis, by excision of the vestibule, may thus be explained in a similar way to the relief of post-herpetic neuralgia that is sometimes obtained by surgical removal of the painful skin [35]. The hyperinnervation phenomenon may be akin to 'collateral sprouting' [36].…”

The Electrical Response to Injury: Molecular Mechanisms and Wound Healing

“…Neurons also grow in response to skin wounds, 61 and nerve growth toward cornea wounds is stimulated and directed by the endogenous wound electric signal. 62 These results led to the hypothesis that applied EFs may help heal chronic nonhealing wounds where other treatments have failed.…”

Immunohistochemical comparison of whisker pad cutaneous innervation in Swiss Webster andhairlessmice

“…The mutant mouse strain, hairless (Hr) (Mann and Straile 1961;FitzGerald et al 1971FitzGerald et al , 1975Mann 1971; see Benavides et al 2009 for review) comprises a unique model with which to analyze nervous plasticity related to changes in cutaneous target tissues. Hairless is an autosomal recessive allelic mutation of murine chromosome 14 resulting in a deficiency in production of a transcriptional corepressor that likely regulates the expression of one or more proteins involved in normal hair cycling Panteleyev et al 1998aPanteleyev et al , 2000Potter et al 2001;Benavides et al 2009).…”

“…Over the next 2-3 weeks, however, they permanently lose virtually all of their fur hair follicles, leaving only the vibrissal follicles on their muzzle (i.e., mystacial pad) and a few thin, irregular hairs in their skin. Hr mice have been useful as a model for studying hair cycling (Mann and Straile 1961;Mann 1971;Sundberg et al 1989Sundberg et al , 1999Panteleyev et al 1998aPanteleyev et al , 1998bMassironi et al 2005), the effects of ultraviolet light, chemicals, and abrasion on the skin (FitzGerald et al 1975; see Armstrong et al 1997 for a review), and transdermal drug delivery (see Hammond et al 2000;Kanikkannan et al 2000;Ramachandran and Fleisher 2000;Benavides et al 2009 for reviews). However, few neuroanatomical reports could be found using Hr as a model.…”