The architecture and structure of alpaca skin (Vicugna pacos): impacts on industry and wool trade

Abstract Background: Alpacas are reared mainly for fiber extraction, which is a highly valued product in the textile industry. For this reason, this work aims to evaluate the morphological and quantitative aspects of the light and dark alpaca skin of Huacaya and Suri alpacas, comparing the structure and architecture of the scapular, costal and lateral femoral skin. Biopsies were collected from the skin of 12 alpacas from the Pacomarca Experimental Fund, located at Puno - Peru. The samples were weighed and fixed in 10% aqueous formalin solution for histological procedures. The histological sections were stained with Hematoxylin eosin, Picrossirius red and Masson Trichromic and immunostained for types I, III and IV collagen and S100.Results: The derma presented sebaceous and sweat glands, as well as follicular groups with primary and secondary hair follicles. Each follicle had a hair called fiber, some with medulla and some without, but both surrounded by cortex and cuticle. The skin presented similar immunostaining for type I, II and IV and S100. Collagen III was detected only in the derma. The total volume of the skin, derma, follicular groups and sebaceous and sweat glands was estimated by stereology for the three body regions for both Huacaya and Suri alpacas. The total volume of skin (Vref) and total volume of follicular groups (VGF) were different for body regions. Femoral region showed higher values for VGF. Colour and breed were also different for Vref and total volume of derma (VD).Conclusion: Comparing the two breeds the femoral region presented higher fiber production. Dark animals had more derma and it was reported close relationship between total skin volume and their fractions volumes: derma, follicular groups and sweat glands.