insect external sensillum insect eo-type sensillum eso Sensillum with innervated external cuticular sensory structure consisting of one or more bipolar sensory neurons, and 3 support cells: a trichogen cell which makes the external cuticular sensory structure, a thecogen cell which makes the socket that holds the base of the external sensory structure and a tormogen cell which makes the cuticular matrix (cap) at the tip of the innervating dendrite(s). FBbt:00007232 UBERON:6007232