The phenomenon of ‘Beading’ in olfactory dendrites of the male silkmoth antheraea pernyi GUÉRin-ménéville (Lepidoptera : Saturniidae)

Along the olfactory dendrites of the silkmoth Antheraea pernyi (Lepidoptera : Saturniidae), dilations called beads are formed in vivo during (a) the aging of the animal and (b) after cutting the dendrites. Beads show 3 different morphologies : (i) splaying of the microtubules within them, (ii) detachment of the membrane from the microtubular bundle without the splaying of microtubules, and (iii) total depolymerization of microtubules. The latter is especially common in the tips of the dendrite after cutting with tweezers. The most likely reason for the formation of these beads is the calcium-induced damage to the microtubular and membrane cytoskeleton as evidenced by acridine orange staining. From the electrophysiological point of view, the beaded dendrites at the cut tips are considered to be functional, because normal responses to pheromones can be recorded directly over cut hairs, and such responses have been found similar to recordings from uncut hairs. How age related beading affects electrophysiological recordings is yet to be determined.