part of antennal segment 3 sense organ trichoid sensillum of antennal segment 3 VFB:FBbt_00004173 Morphology is consistent with these sensilla being olfactory (Shanbhag et al., 1999). This function has been directly confirmed by electrophysiology (Clyne et al., 1997). sensillum trichodeum of antennal segment 3 FBbt:00004173 antennal trichoid sensillum at fly_anatomy.ontology Olfactory sensillum of antennal segment 3 whose external sensory part is a sharply pointed hair arising from a conspicuous cylindrical base. The walls of the hair are perforated by irregularly distributed pores connecting to a lymph filled lumen containing 1-3 ORN dendrites, unbranched except occasionally near the hair tip. third segment of antenna olfactory sensory organ trichoid sensillum adult antennal sensillum