Sensitivity of touch corpuscles in vitamin A-deficient rats.

Fifty percent of a population of thirty weanling rats were fed a vitamin A-deficient diet. The remaining 50% were fed a control diet. In comparison with the control group, the rate of growth started to slow down in the vitamin A-deficient animals around day 33. Single unit recordings were made from sensory nerve fibres supplying slowly adapting type I cutaneous mechanoreceptors (touch corpuscles). Touch corpuscles were stimulated repetitively with low force mechanical stimuli. Receptors in vitamin A-deficient animals showed clearly reduced nervous responses compared with receptors in control animals. Most receptors remained responsive even after prolonged repetitive stimulation.