Ultrastructure of a terminal chordotonal sensillum in larval antennae of the yellow mealworm, Tenebrio molitor L.

The third (terminal) segment of the antenna of the final instar larva of Tenebrio molitor contains a single, unusually positioned and attached chordotonal sensillum. This sensillum consists of four cells: a microtubule-filled attachment cell anchoring the sensillum in the basement membrane-like extracellular matrix of the segment, a scolopale cell containing a strongly developed fibrous scolopale ensheathing the dendrite, a typical type I bipolar neuron, and a basal glial cell. The ultrastructure of this sensillum and its relationships to other antennal structures are described and compared with other chordotonal sensilla reported in the literature.