The structure of the tarsal chemoreceptors of the blowfly, phormia regina meigen

Abstract

Since tlie discovery by Xnnicli ( '21) of the sensitivity of the legs of Lepidoptera to sugar, the preseiice of tarsal chemoreceptors has been demonstyated in numerous insects, and a considerable amount of physiological iiiformatioii concerning them has been obtained (for reviews see Dethier and Chadwick, '48 and Friiigs and Fring-s, '49). Homever, studies of the identity of these structures have lagged considerably behind the pliysiol~ogical iiivestigations so that, as f a r as the authors a r e aware, no unequivocal correlation of a tarsal seiisillum with a chemoreceptive fuiiction bas been made.Only a few reports of histological studies of tarsal seiisilla in general occur in tlie literatiire. Mcliiiloo's ( '16'34) "olfactory pores" (campaiiifoim seiisilla) have been shown to be proprioceptors (Pringle, '%a, '38b). Eltringham ( '33) described on the butterfly P~~lrrrnteis afalmatii L., and Hayes and Liu ( '47) on iVusca doiiiestica L., thin-walled tarsal hairs mliich were associated with groups of sense cells and were, therefore, coiisidered to be chemoreceptors. Iiinervated hairs containing a large eccentricallp located cavity and a smaller cavity in the heavy portion o f tlic wall were found 011 the tarsi and proboscis of the fly Calliphorcr ergth rocephala Meigeii by Tinbergen ('39) who postulated on the basis of the structure aiid distributioii of these seiisilla that they were chemoreceptors.National Science Foundation Fellow.

Identified antennular near-field receptors trigger reflex flicking in the crayfish

“…Nonetheless, it remains unclear how the reflex could be evoked by stimulation of just the one or two sensory neurons associated with a single feathered sensillum, against the background of frequent random spiking generated by the entire array of sensilla. Even though this is not the only arthropod sensillum-triggered reflex behavior evoked by activation of one or two sensory axons (Lewis, 1953;Grabowski and Dethier, 1954), it occurs against the background of considerable sensory noise. Although the explanation for this conceptual problem is presently unknown, one possibility is that direct electrical connections between sensillar afferent terminals amplify the amount of synaptic transmitter released by spikes that arrive at the brain over an axonal pathway.…”

Étude au microscope électronique à balayage des organes sensoriels deCulicoides nubeculosus(Diptère : Cératopogonidé)

“…Diether a postulé que les récepteurs appropriés à la chimioréception ont en commun un caractère significatif qui est la présence des pores permettant aux molécules excitatrices d'accéder aux terminaisons nerveuses situées à l'intérieur des sensilles (in C. T. Grabowski et V. G. Dethier, 1954).…”

Chemosensory Physiology in an Age of Transition

“…Early in 1953, a student, Grabowski, and I succeeded by micro topical application of sucrose to single hairs in demonstrating unequivocally that the gustatory end-organs of the tarsi were hairs (setae) similar in appear ance to those on the labellum, which Minnich had identifi ed as gustatory (Grabowski & Dethier 1954). We were able to prove that the tips were not covered with cuticle, that the hairs were innervated by three bipolar sensory neurons (later examination with an electron microscope revealed two additional neurons), and that each of the cells responded to a different sensory modality.…”