Branched form of the encapsulated dermal receptors in rats

: Using electron microscope the receptors found in the zone of highest receptor sensitivity in the skin fold at the base of IV finger of rat hind limb were studied. These receptors are represented by complex incapsulated corpuscles consisting of a group of small endings similar to Pacinian corpuscles, which are densely packed and surrounded by a common connective tissue capsule. Each single primary receptor is provided with an unmyelinated receptor terminal, analogue of internal bulb, and a multilayered external bulb. Primary receptor differs from Vater-Pacinian corpuscle by a significantly smaller size, form of sensitive terminal in cross-section, small number of layers forming internal and external bulbs. Complex corpuscle is the derivative of n. tibialis myelinated sensory fiber. The later is divided after the loss of myelin forming a platform of division with several (up to 5) short sprouts and separate incapsulated receptors at their ends. The complex corpuscles described apparently are dermal mechanoreceptors.