Mitochondrial distribution within the terminal neurite of the pacinian corpuscle.

Electron-microscopic analyses of the mitochondrial organization within the neurite innervating the Pacinian corpuscle (PC) were performed to test the hypothesis that the sites of mechanotransduction are the filopodia projecting from the neurite's surface. Since high concentrations of mitochondria imply the need for metabolic energy, and since transduction mechanisms are heavily dependent on such energy, it was reasoned that the greatest concentration of mitochondria should occur near the filopodia if they are involved in mechanotransduction. The analysis that the mitochondria lie close to the terminal neurite's membrane, on average within 0.4 microns, and thus are ideally located for supplying energy for membrane mechanisms. Although they can be found in a ring-like array, as seen in cross-sections of the terminal neurite, their greatest concentration occurs where the filopodia project from the terminal neurite. A linear algebraic analysis of the data set confirmed a high probability of the joint occurrence of a filopodial base and an increased frequency (number) of mitochondria. Thus the results provide further circumstantial support for the hypothesis that transduction within the PC mechanoreceptors takes place at or near the filopodia.