| Objective :To evaluate the cutaneous innervation of normal human skin and the innervation of scar tissue, and find the difference between normal human skin and scar tissue.Methods: Thirty normal full-thickness skin samples from adult cadavers and sixty two scar samples from surgical procedures involving-patients were analyzed. The samples were from different sites: face, thorax, abdomen, thigh and calf. Each sample was cut into two pieces, one was fixed in paraformaldehyde for paraffin sections, the other were put into liquid nitrogen for frozen sections. Series sections, which were ten or fifteen μ m in thickness, were produced in a Leica RM 2135 Slicer or Leica CM 1900 Cryosat. All the samples were divided into 4 groups, group A stand for the normal skin, B for hyerplastic scar, C for the mature scar, D for Keloid .The sections were stained by haematoxylin and eroin, The innervation was detected using a new marker of neural cells- sheep antibody to human protein gene products 9.5 (pgp9.5). The results were analyzed with image analyze software.Result: The stained fibers were brown and went their way from reticular dermis toward epidermis with branches. They take on a elliptical, round or linear look because of different transect, and on the whole some looked just like a tree. Many nerve trunks accompanied with vessels and their branches were observed in subcutaneous tissue; The cutaneous nerves were found located nearby the small vessels, around sweat glands, sebaceous glands and folliculus in the reticular dermis. The nerve fibers were beneath the epiderm projecting, and they were thin and dense. The normal skin innervation is 60.8±14.7,and the innervation of face is evidentlyhigher than the others with a density of 90.6± 19.97.The hyperplastic scar tissue was 94.28 ± 6.93,while the mature was 41.14±16.The innervation of keloid tissue, however, is 48.2±18.There were collagen mass which were circled with fiberblast cells in scar tissue. The vessels and nerve fibers were rich. The nerve fibers, which were thin and dense, were irregular. Some site have a high density of 160 per unit, however some other sites nearly had nothing. Hyperplastic scar tissues within 1 year posses more nerve fibers, which were thin and dense, than the normal skin and scar tissue during autumn. The collagen became fairly well-regulated and there were less nerve fibers in the mature scar. The innervation of group B is evidently higher than A and C(p<0.01),and group C is lower than the group A(p<0.05).Conclusion: The character of cuatneous innervation were similar to that of cutaneous vessel, which may provide a theory evidence to the symptom of itch and pain of burns. There were more thin and dense nerve fibers in scar during hyperplasia stage than the scar in the autumn, thus nerve system may take an important role in the wounds healing process and forming of scar, which hints that local application of nervepeptide may be a promising method to accelerate the wound healing and to prevent the formation of the scar. Less innervation in the mature scar may contribute to the scar ulcer . From our data there was no correlation between the innervation of scar and age, however the innervation was changed with the evolvement of scar, our data shew that the innervation decreased with time. Study the innervation via immunohistochemistry method with sheep antibody to human PGP9.5 can fairly show thin cutaneous nerve fibers, but we can not pick out the epidermis nerve fibers endings from the melanin very well in the base layer, for they all were brown and yellow. So some technique that manages the disturbance of the melanin well is required.
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