DIFFERENT EFFECTS OF WARM REARING AND HEAT ACCLIMATION ON THE DEVELOPMENT OF CUTANEOUS ARTERIOVENOUS ANASTOMOSES IN RATS

1. The density of arteriovenous anastomoses (AVAs) and the thickness of the epidermis in skin samples taken from different regions were studied in 4 control, 4 warm-reared and 4 warm-acclimated rats. 2. There were very few AVAs in ear pinna but there were no effects of warm rearing and warm acclimation on AVAs density in this region. The epidermis thickness was not modified by both adaptation procedures. 3. The AVAs were abundant in scalp, foot and in the distal part of tail. Although warm rearing and warm acclimation increased the density of AVAs and decreased the epidermis thickness in these regions the acclimation mimicked the effects of the rearing only in part. 4. In conclusion, warm rearing selectively stimulates the development of thermolytic effectors such as tail, feet and scalp in rats. These irreversible changes are significantly more pronounced than the reversible shifts occurring during warm acclimation in adult animals.