Stretching of an isolated part of the sciatic nerve of the frog (Rana rindibunda) causes excitation of its sensory nerve fibres.

The stretching of the isolated distal part of the sciatic nerve of the frog causes the excitation of a number of its nerve fibres. The excitation lasts as long as the force is applied, indicating a slow adapting mechanoreceptor system. The fact that in experiments in situ stretching of the sciatic nerve causes the reflex activation of the femoral muscles is a clear indication that the activated nerve fibres belong to primary afferent fibres. According to the results of this study either some of the primary afferent fibres in the sciatic nerve of the frog also have the potential of stimulus transduction (mechanical tension) or the sciatic nerve is equipped with nerve terminals which are sensitive to stimulus energy. The implication of this sensory mechanism in the proprioception of the leg is discussed further.