(a) Antennae of insects with sexual dimorphism: (i) Saturniid moth (Antheraea pernyi), (ii) scarabid beetle (Rhopaea sp.), (iii) honeybee (Apis mellifera L.). (Modified from Kaissling K.E. 1987. In R.H. Wright Lectures on Insect Olfaction, K. Colbow (ed.), 1–190. Burnaby, B.C., Canada: Simon Fraser University.) (b) Antenna of a male saturniid moth (see ai), central part of two segments with several types of sensilla. The long hairs, sensilla trichodea, are innervated by two or three pheromone receptor neurons. Shorter hairs and sensilla coeloconica (circles). Three bristles (above) for taste and mechanical stimuli. Sensilla styloconica for humidity and temperature (upper edge). (Modified from Kaissling K.E. 1987.) Inset: Head of Drosophila with one antenna, same scale. The third segment (funiculus) is covered with numerous tiny (10-µm) hair-like olfactory sensilla.
(c) Electron microprobe analysis. The diagrams result from single sensillum lymph droplets (Figure 4.2i), and from fine threads made from hemolymph. Abscissa: Energy of emitted x-rays (1–4 keV), characteristic for each element. Ordinate: relative numbers of counts. The relative concentrations of the elements are obtained if one raises the peak amplitudes by calibration factors (3.5 for Na, 2.4 for Mg, 1.1 for P, 1.2 for S, 0.98 for Cl, 1 for K, and 0.93 for Ca). According to flame photometry, the concentration of K+ within the sensillum lymph was about 200 mOsmol/l, and within the hemolymph 36 mOsmol/l. The sulfur peak originates from the PBP with 14 sulfur atoms per molecule of ApolPBP1, or 15 sulfur atoms per molecule of AperPBP1 and AperPBP2. (Modified from Kaissling K.E. and Thorson J. 1980. Insect olfactory sensilla: Structural, chemical and electrical aspects of the functional organisation. In Receptors for Neurotransmitters, Hormones and Pheromones in Insects, D.B. Sattelle, L.M. Hall and J.G. Hildebrand (eds.), 261–282. Amsterdam: Elsevier/North-Holland Biomedical Press). (d) The glass capillary of the recording Ag/AgCl-electrode filled with sensillum lymph Ringer (Kaissling 1995) is slipped over one of several cut hairs. The reference electrode (outside the photo) supports the isolated antennal branch. Another capillary is directed to the middle of the hair for locally applying airborne stimuli. (Modified from Kaissling K.E. 1974. Sensory transduction in insect olfactory receptors. In Biochemistry of Sensory Functions, 25. Mosbacher Colloquium der Gesellschaft für Biologische Chemie, L. Jaenicke (ed.), 243–273. Berlin: Springer Verlag; Kaissling K.E. 2009. J. Comp Physiol A 195:895–922.)