The fine structure of male Johnston's organ of Chironomus plumosus L. (Diptera, Chironomidae).

摘要

The male Johnston's organ in Chironomus plumosus was investigated by light and electron microscopy. The base of the third segment of antenna bears the radial array of 90-93 long thin cuticular prongs which pass through the holes in the inner edge ofpedicel and penetrate deeply into its cavity where 225-230 scolopidia of A and B types attach to the inner and outer surface of each prong. Type A scolopidia are composed of 2 sensory cells, an envelope cell with scolopale, a cap cell that produces theadditional distal scolopale and thin extracellular sheath, and a long tubular cap attaching to a prong. Each dendrite terminates with a ciliary structure that contains a distal basal body, 9 double peripheral fibrils and a dilation filled with electron-dense material. A-type scolopidia are the most abundant in Johnston's organ and their number is about 20thin000. B-type scolopidia differ from the preceding ones in possessing a third sense cell in which the ciliary structure contains a packet of microtubules. Only 3 scolopidia of this type attach to the base of each prong and tips of their caps slightly extend through the holes in the inner edge of pedicel. The ultrastructure of chironomid and culicid Johnston's organs is compared.