Pheromone stimulation in perfused sensory, hair of the moth Antheraea polyphemus

Olfactory hairs of moths antennae were perfused with electrolyte during electrophysiological recording. The perfusate was drawn from the recording capillary electrode into the apically opened hair by applying suction on the haemolymph side. Due to suction, the receptor cell dendrite partially withdraws from the hair lumen. The withdrawal of receptor cell dendrites was examined by electron microscopy and after staining with lucifer yellow. In the withdrawn position the dendrite cannot be excited by airborne pheromone stimuli applied to the middle of the hair but it responds to pheromone dissolved in the perfusate. The normal position of the dendrite and its responses to external stimulation can be restored by applying pressure to the haemolymph side. These results show that pheromone molecules may stimulate olfactory cells directly without mediation by cuticular structures. Furthermore, the method of hair perfusion allows application of water-soluble agents to living dendrites of insect olfactory receptor cells.