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Neuronal organization of the hemiellipsoid body of the land hermit crab, Coenobita clypeatus : Correspondence with the mushroom body ground pattern
Author(s) -
Wolff Gabriella,
Harzsch Steffen,
Hansson Bill S.,
Brown Sheena,
Strausfeld Nicholas
Publication year - 2012
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.23059
Subject(s) - mushroom bodies , biology , periplaneta , hermit crab , cockroach , crustacean , insect , antennal lobe , anatomy , zoology , ecology , decapoda , biochemistry , drosophila melanogaster , gene
Malacostracan crustaceans and dicondylic insects possess large second‐order olfactory neuropils called, respectively, hemiellipsoid bodies and mushroom bodies. Because these centers look very different in the two groups of arthropods, it has been debated whether these second‐order sensory neuropils are homologous or whether they have evolved independently. Here we describe the results of neuroanatomical observations and experiments that resolve the neuronal organization of the hemiellipsoid body in the terrestrial Caribbean hermit crab, Coenobita clypeatus , and compare this organization with the mushroom body of an insect, the cockroach Periplaneta americana . Comparisons of the morphology, ultrastructure, and immunoreactivity of the hemiellipsoid body of C. clypeatus and the mushroom body of the cockroach P. americana reveal in both a layered motif provided by rectilinear arrangements of extrinsic and intrinsic neurons as well as a microglomerular organization. Furthermore, antibodies raised against DC0, the major catalytic subunit of protein kinase A, specifically label both the crustacean hemiellipsoid bodies and insect mushroom bodies. In crustaceans lacking eyestalks, where the entire brain is contained within the head, this antibody selectively labels hemiellipsoid bodies, the superior part of which approximates a mushroom body's calyx in having large numbers of microglomeruli. We propose that these multiple correspondences indicate homology of the crustacean hemiellipsoid body and insect mushroom body and discuss the implications of this with respect to the phylogenetic history of arthropods. We conclude that crustaceans, insects, and other groups of arthropods share an ancestral neuronal ground pattern that is specific to their second‐order olfactory centers. J. Comp. Neurol. 520:2824–2846, 2012. © 2012 Wiley Periodicals, Inc.