title: Constancy and variability of identified glomeruli in antennal lobes: computational approach in Spodoptera littoralis.
abstract: The primary olfactory centres share striking similarities across the animal kingdom. The most conspicuous is their subdivision into glomeruli, which are spherical neuropil masses in which synaptic contacts between sensory and central neurons occur. Glomeruli have both an anatomical identity (being invariant in location, size and shape) and a functional identity (each glomerulus receiving afferents from olfactory receptor neurons that express the same olfactory receptor). Identified glomeruli offer a favourable system for analysing quantitatively the constancy and variability of the neuronal circuits, an important issue for understanding their function, development and evolution. The noctuid moth Spodoptera littoralis with its well-studied pheromone communication system has become a model species for olfaction research. We analyse here its glomerular organisation based on ethyl-gallate-stained and synapsin-stained preparations. Although we have confirmed that the majority of glomeruli can be individually identified in various antennal lobes, we have recognised several types of biological variability. Some glomeruli are absent, possibly indicating the lack of the corresponding receptor neuron type or its misrouting during development. The antennal lobes vary in global shape and, consequently, the spatial location of the glomerular changes. Although they do not prevent glomerulus identification when quantitative analysis methods are used, these variations place limits on the straightforward identification of glomeruli in functional studies, e.g. calcium-imaging or single-cell staining, when using conventional three-dimensional maps of individual antennal lobes.
authors: INRA, UMR 1272 Physiologie de l'Insecte, Versailles, France.
authors: Louise
authors: L
authors: Couton
authors: Sebastian
authors: S
authors: Minoli
authors: Kiên
authors: K
authors: Kiêu
authors: Sylvia
authors: S
authors: Anton
authors: Jean-Pierre
authors: JP
authors: Rospars
mesh_terms: D000818:Animals; D003198:Computer Simulation; D008297:Male; D008954:Models, Biological; D018034:Olfactory Receptor Neurons / Q000166:cytology; D018411:Spodoptera / Q000166:cytology*; D013194:Staining and Labeling