ULTRASTRUCTURE OF ANTENNAL SENSILLA OF NEBRIA-BREVICOLLIS (FAB) (COLEOPTERA, CARABIDAE)

The antenna of the cat abid beetle, Nebria brevicollis, has approximately 5775 sensilla, 84% trichoid and 16% basiconic, represented by 4 and 3 size classes respectively. The ultrastructure of trichoid type 1 (44 ± 1 μm long, 78.3% of all sensilla) is characterised by a single neuron whose dendrite terminates in a tubular body and by 4 enveloping cells with a complex system of interconnections. Trichoid type 2 (55 ± 0.9 μm long, 4.2% of all sensilla) has 5 neurons one of which terminates in a tubular body and the others are unbranched in the peg. The peg of the basiconic type I sensillum (5.2 ± 0.2 μm long, 14% of all sensilla) is perforated by about 870 pores, from which pore tubules run to the much branched dendrites of 2 neurons. The presence of pinocytotic 40 nm vesicles in the microvilli of a basiconic enveloping cell indicates it has a secretory function. Evidence of direct contact in the sensory cell between endoplasmic reticulum and onion body suggests a role in protein secretion for the latter. © 1979.