Bristle sensilla

Schematic cross-section of an insect bristle sensillum. Each bristle is composed of a hair with its base fixed to the dendrite of a sensory neuron. The hair acts as a lever that exerts force on the dendrite, inducing mechanotransduction channels to open and producing electrical currents.
Bristle sensilla on the edge of a fruit fly wing. Green fluorescent labeling shows where sensory neurons innervate the bristles. In this image, some of the neurons are mechanosensory and some are gustatory.

Bristle sensilla are a class of mechanoreceptors found in insects and other arthropods that respond to mechanical stimuli generated by the external world.[1] As a result, they are considered exteroceptors. Bristle sensilla can be divided into two main types, macrochaete and microchaete, based on their size and physiology.[2][3] The larger macrochaete are thicker and stouter than the smaller microchaete. Macrochaete are also more consistent in their number and distribution across individuals of the same species. Between species, the organization of macrochaete is more conserved among closely related species, whereas the organization of microchaete is more variable and less correlated with phylogenetic relatedness.[4][5]

Each bristle sensillum is composed of a hollow hair with its base fixed to the dendrite of a sensory neuron. The hair acts as a lever. When the hair is deflected, for example by dirt or parasites, force is exerted on the dendrite. This induces mechanotransduction channels to open, producing an electrical signal that is carried along an axon to the central nervous system.[1]

Bristles are directionally selective to mechanical deflection. Fly bristles are typically angled 45° relative to the cuticle, and most bristle neurons are most sensitive to forces that push the bristle toward the cuticle.[6] Movement of even a single bristle is sufficient to trigger an insect to groom.[7]

  1. ^ a b Tuthill, John C.; Wilson, Rachel I. (2016-10-24). "Mechanosensation and Adaptive Motor Control in Insects". Current Biology. 26 (20): R1022–R1038. doi:10.1016/j.cub.2016.06.070. ISSN 0960-9822. PMC 5120761. PMID 27780045.
  2. ^ Keil, T. A. (1997-12-15). "Functional morphology of insect mechanoreceptors". Microscopy Research and Technique. 39 (6): 506–531. doi:10.1002/(SICI)1097-0029(19971215)39:6<506::AID-JEMT5>3.0.CO;2-B. ISSN 1059-910X. PMID 9438251. S2CID 5552615.
  3. ^ Simpson, P.; Woehl, R.; Usui, K. (1999-04-01). "The development and evolution of bristle patterns in Diptera". Development. 126 (7): 1349–1364. doi:10.1242/dev.126.7.1349. ISSN 1477-9129. PMID 10068629.
  4. ^ Sturtevant, A. H. (1970-01-01). "Studies on the bristle pattern of Drosophila". Developmental Biology. 21 (1): 48–61. doi:10.1016/0012-1606(70)90060-6. ISSN 0012-1606. PMID 5445760.
  5. ^ Usui-Ishihara, Akiko; Simpson, Pat (2005-01-01). "Differences in sensory projections between macro- and microchaetes in Drosophilid flies". Developmental Biology. 277 (1): 170–183. doi:10.1016/j.ydbio.2004.09.017. ISSN 0012-1606. PMID 15572148.
  6. ^ Walker, Richard G.; Willingham, Aarron T.; Zuker, Charles S. (2000-03-24). "A Drosophila Mechanosensory Transduction Channel". Science. 287 (5461): 2229–2234. Bibcode:2000Sci...287.2229W. doi:10.1126/science.287.5461.2229. ISSN 0036-8075. PMID 10744543.
  7. ^ Corfas, G; Dudai, Y (1989-01-01). "Habituation and dishabituation of a cleaning reflex in normal and mutant Drosophila". The Journal of Neuroscience. 9 (1): 56–62. doi:10.1523/JNEUROSCI.09-01-00056.1989. ISSN 0270-6474. PMC 6569995. PMID 2913213.