basiconic sensillum of antennal segment 3 large basiconic sensillum of antennal segment 3 Large, olfactory basiconic sensillum of antennal segment 3, measuring around 12 micrometers in length and 2.5 micrometers in width, with a blunt tip (Shanbhag et al., 1999). Directly above the base of the sensillum, the shaft diameter is often somewhat reduced resulting in a club-shaped appearance (Shanbhag et al., 1999). The external sensory structure is perforated by pores, arranged along a complicated pattern of branched lines, that connect to a lymph-filled lumen containing the highly branched dendrites of 2-4 ORNs (Shanbhag et al., 1999). large sensillum basiconicum of antennal segment 3 fly_anatomy.ontology VFB:FBbt_00004175 FBbt:00004175 olfactory sensory organ