THE DROSOPHILA ANTENNA - ULTRASTRUCTURAL AND PHYSIOLOGICAL-STUDIES INWILD-TYPE AND LOZENGE MUTANTS

The physiology and ultrastructure of the antenna in Drosophila melanog aster have been examined in wild-type and lozenge mutants. Scanning el ectron microscopy (SEM) of sensilla on the antennal surface has reveal ed that in the wild-type the basiconic sensilla contain linear arrays of pores connected by longitudinal furrows and transected by shorter f urrows. Sensilla trichodea also are shown to have pores, as revealed b y examining transverse sections by transmission electron microscopy (T EM); these data directly address a longstanding controversy. Coeloconi c sensilla, previously described as ''pit sensilla'' and as ''grooved' ' sensilla, are shown to rise directly from the antennal surface, as o pposed to lying below the antennal surface in pits; the previously obs erved grooves correspond to the junctions between bundled, finger-like projections. This description of coeloconic sensilla is supported by analysis of lz mutants, in which the projections of coeloconic sensill a splay apart. Coeloconic sensilla are also shown to undergo duplicati on on the lz(3) antenna. Physiological recordings from the antenna sho w that responses to all odorants tested are severely decreased in lz m utants. Measurements made from different parts of the antenna show sim ilar defects. Evidence is provided that both the physiological and ult rastructural defects map to the lz locus.