Mechanical stimulation is sensed by a cockroach through the spines (Campaniform sensilla) on its leg. There is a burst of spikes in the bipolar nerve cell (sensory neuron) associated with the spine, by pressing gently on the mechanoreceptor apparatus in the cockroach leg.
Colchicine or vinblastine, drugs known to disassemble microtubules, are inferred to disrupt the sense of touch in a cockroach. From 1 to 2 hr after exposure of the leg spine to colchicine or vinblastine, electron microscopy showed no microtubules in the bipolar cell connected to the sensilla, and the typical burst of spikes produced by the tactile probe was replaced by neuronal silence after colchicine drug treatment.
Besides the physical evidence showing microtubule detachment from the basal body in the cockroach spine, there was a change in the electrophysiological response of the bipolar nerve cell after microtubule disruption. These experiments support the hypothesis that sense perception is related to the organization of microtubules in the dendrites of neurons. It is suggested that the proliferation of microtubules in sensory processes may serve to increase the gain of the cell membrane.
Moran D. T. and F. G. Varela. (1971). Microtubules and sensory transduction. Proc.Natl.Acad.Sci.U.S.A. 68, 757-760. 10.1073/pnas.68.4.757