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A Comparative Study of Melanin Content and Skin Morphology for Three Commonly Used Laboratory Swine (Sus scrofa domestica)

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Final technical rept. May 2009-may 2011

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Yorkshire and Yucatan Mini-pig breeds have been commonly used for laser-tissue studies. The newer Yucatan Micro-pig breed has not been used in laser-tissue studies, but could be an alternative to meet logistical needs for laser-tissue studies if its skin is comparable to the accepted Yorkshire and Yucatan Mini-pig breeds. This study sought to contrast the differences in skin thickness and melanin content in pig skin across domestic swine breeds. Skin thickness was measured using HE stained slides while the melanin index ratio of melanin area to a selected area of tissue was measured using a Fontana-Masson stain. Six biopsies were acquired from the flanks of each subject eight Yorkshire pigs, two Yucatan Mini-pigs, and one Yucatan Micro-pig. Statistically significant intra-breed variations in the thicknesses of the stratum corneum, epidermis and dermis were found between equivalent sample sizes in the Yorkshire group. The Yucatan Micro-pig was found to have skin thicknesses more similar to the Yucatan Mini-pigs compared to the Yorkshire. Results for the melanin index values indicate that the Yorkshire pig breed is most likely to have an average melanin index near 0.37, with the Yucatan Mini- and Micro-pigs trending towards melanin index values greater than that of the Yorkshire pig breed. The sample sizes for the Mini- and Micro-pigs were insufficient to assess the complete melanin index values between breeds. Though this is not an equivalent sample size comparison, results indicate that the skin thickness and melanin distribution in the new Micro-pig are more similar to the Yucatan Mini-pig and not the Yorkshire breed, suggesting the Micro-pig may be a suitable substitute for experiments which have traditionally used the Mini-pig.

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  • Biology
  • Anatomy and Physiology
  • Medicine and Medical Research

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