[Localization of cold thermoreceptors in various layers of the skin]

Impulses from cold thermoreceptors were recorded during changes of the temperature in superficial and deep skin layers of the rabbit upper lip. The temperature of stimulating thermodes was sharply changed from 20 degrees C to 40 degrees C and back again in each of the thermodes. 7 out of 10 receptors revealed sharp alterations in the impulse flow following changes of the temperature in the surface thermode, whereas changes of temperature in the deep thermode (2-3 mm under the skin) induced slow alterations in the activity of the same receptor. 3 receptors responded only to changes in the deep thermode. The data suggest that thermoreceptors can be found in different skin layers and register the skin temperature gradient or the heat flows across the skin. This enables to propose a new regard on the mechanism of temperature homeostasis maintenance.