Chapter 7 Evidence that the Merkel cell is not the transducer in the mechanosensory Merkel cell – neurite complex

Publisher This chapter focuses on the evidence that the merkel cell is not the transducer in the mechanosensory merkel cell — neurite complex. The application of electron microscopy (EM) used with correlative electrophysiology confirmed some of Merkel's original observations and suggestions. There are, however, a number of difficulties regarding Merkel cell function. First, aside from older observations suggesting that the mechanosensory nerve endings are likely to be excitable by acetylcholine there is no plausible candidate for the role of the putative transmitter. Second, chemical synaptic transmission was thought to be too slow to explain the ability of mechanosensory units in the vibrissae of the cat to “follow”, one-to-one, a high frequency vibratory stimulus. Third, if the Merkel cell is the transducer then it should itself be mechanosen sitive. The chapter concludes that the initiation of mechanosensory responses from Merkel cell— neurite complexes, both in the rat touch dome and in Xenopus skin, does not require the presence of the Merkel cell, and, therefore, that the Merkel cell is not the mechanosensory transducer.