THE STRUCTURE AND TENSILE PROPERTIES OF THE SKIN OF TIGHT-SKIN (Tsk) MUTANT MICE

In this study we examine the structure and tensile properties of the skin of tight-skin (Tsk/+) mice. The effects of this mutation appear to be confined to the connective tissues and are particularly manifest in the skin which feels abnormally tight. A comparison of the load/extension relationship of dorsal skin from Tsk/+ and normal (+/+) siblings was evaluated by means of an Instron extensometer. The skin of Tsk/+ mice was found to be stiffer than normal when stretched in the long axis of the body and in addition appeared to lack much of the directional difference in tensile properties which characterizes normal skin. Light microscopical study of skin from the ear, back, and abdomen showed that the dermis of Tsk animals is substantially thicker than normal and lacks the regular weave typical of normal dermal collagen fibers. The hypodermis of Tsk mice is also hypertrophic and in places appears to be firmly attached to deeper tissues. These data suggest that while the “tightness” of Tsk skin is most likely a result of dermal attachment to deep tissues, the unusual tensile properties of the excised skin may be at least in part a result of an alteration in the fibrous architecture of the dermis. Finally, certain similarities are noted between the cutaneous abnormalities of Tsk/+ mice and that of systemic scleroderma in man