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Brain anatomy in Diplura (Hexapoda).

Böhm A, Szucsich NU, Pass G - Front. Zool. (2012)

Bottom Line: In the past decade neuroanatomy has proved to be a valuable source of character systems that provide insights into arthropod relationships.In contrast, Archaeognatha completely lack mushroom bodies and exhibit a central body organization reminiscent of certain malacostracan crustaceans.Several hypotheses of brain evolution at the base of the hexapod tree are discussed.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Evolutionary Biology, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria. a.boehm@univie.ac.at.

ABSTRACT

Background: In the past decade neuroanatomy has proved to be a valuable source of character systems that provide insights into arthropod relationships. Since the most detailed description of dipluran brain anatomy dates back to Hanström (1940) we re-investigated the brains of Campodea augens and Catajapyx aquilonaris with modern neuroanatomical techniques. The analyses are based on antibody staining and 3D reconstruction of the major neuropils and tracts from semi-thin section series.

Results: Remarkable features of the investigated dipluran brains are a large central body, which is organized in nine columns and three layers, and well developed mushroom bodies with calyces receiving input from spheroidal olfactory glomeruli in the deutocerebrum. Antibody staining against a catalytic subunit of protein kinase A (DC0) was used to further characterize the mushroom bodies. The japygid Catajapyx aquilonaris possesses mushroom bodies which are connected across the midline, a unique condition within hexapods.

Conclusions: Mushroom body and central body structure shows a high correspondence between japygids and campodeids. Some unique features indicate that neuroanatomy further supports the monophyly of Diplura. In a broader phylogenetic context, however, the polarization of brain characters becomes ambiguous. The mushroom bodies and the central body of Diplura in several aspects resemble those of Dicondylia, suggesting homology. In contrast, Archaeognatha completely lack mushroom bodies and exhibit a central body organization reminiscent of certain malacostracan crustaceans. Several hypotheses of brain evolution at the base of the hexapod tree are discussed.

No MeSH data available.


Related in: MedlinePlus

Mushroom bodies of Campodea augens. A) Proximal part of mushroom body 1 (mb1) with intrinsic Kenyon cells (kc). A darkly stained region (asterisk) partially separates the peduncle of mb1 from the neuropil at its base. B) Connection (arrow) of the central body with the lateral accessory lobes (lal), which are in turn connected with the antero-lateral protocerebrum (alp). C) Possible connection of axons passing below mb1 and mb1’ (left arrow; mb1’: branch of mb1 extending to the calyx) and axons of the act2 (antenno-cerebral tract 2, right arrow). D) DC0-like ir (red) and phalloidin staining (green) reveal mb1 and the globular lobe of mb2. E) Detail of mb1. F) Detail of mb2 and its thin peduncle (arrow) which originates from lateral Kenyon cells and closely passes by the calycal glomeruli (asterisk). Scale bars: A, B, E, F: 20 μm, C: 10 μm, D: 50 μm.
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Figure 5: Mushroom bodies of Campodea augens. A) Proximal part of mushroom body 1 (mb1) with intrinsic Kenyon cells (kc). A darkly stained region (asterisk) partially separates the peduncle of mb1 from the neuropil at its base. B) Connection (arrow) of the central body with the lateral accessory lobes (lal), which are in turn connected with the antero-lateral protocerebrum (alp). C) Possible connection of axons passing below mb1 and mb1’ (left arrow; mb1’: branch of mb1 extending to the calyx) and axons of the act2 (antenno-cerebral tract 2, right arrow). D) DC0-like ir (red) and phalloidin staining (green) reveal mb1 and the globular lobe of mb2. E) Detail of mb1. F) Detail of mb2 and its thin peduncle (arrow) which originates from lateral Kenyon cells and closely passes by the calycal glomeruli (asterisk). Scale bars: A, B, E, F: 20 μm, C: 10 μm, D: 50 μm.

Mentions: Small protocerebral lobes (lal, lateral accessory lobes) are connected to the central body (Figure5B), and probably to each other, by a small neurite bundle directly in front of the central body. Anterior of each lal lies the antero-lateral protocerebrum (alp) of the respective hemisphere (Figures2,4 and5B). The alp is intimately connected with the lal, as well as with the remaining protocerebrum and the tritocerebrum.


Brain anatomy in Diplura (Hexapoda).

Böhm A, Szucsich NU, Pass G - Front. Zool. (2012)

Mushroom bodies of Campodea augens. A) Proximal part of mushroom body 1 (mb1) with intrinsic Kenyon cells (kc). A darkly stained region (asterisk) partially separates the peduncle of mb1 from the neuropil at its base. B) Connection (arrow) of the central body with the lateral accessory lobes (lal), which are in turn connected with the antero-lateral protocerebrum (alp). C) Possible connection of axons passing below mb1 and mb1’ (left arrow; mb1’: branch of mb1 extending to the calyx) and axons of the act2 (antenno-cerebral tract 2, right arrow). D) DC0-like ir (red) and phalloidin staining (green) reveal mb1 and the globular lobe of mb2. E) Detail of mb1. F) Detail of mb2 and its thin peduncle (arrow) which originates from lateral Kenyon cells and closely passes by the calycal glomeruli (asterisk). Scale bars: A, B, E, F: 20 μm, C: 10 μm, D: 50 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3585824&req=5

Figure 5: Mushroom bodies of Campodea augens. A) Proximal part of mushroom body 1 (mb1) with intrinsic Kenyon cells (kc). A darkly stained region (asterisk) partially separates the peduncle of mb1 from the neuropil at its base. B) Connection (arrow) of the central body with the lateral accessory lobes (lal), which are in turn connected with the antero-lateral protocerebrum (alp). C) Possible connection of axons passing below mb1 and mb1’ (left arrow; mb1’: branch of mb1 extending to the calyx) and axons of the act2 (antenno-cerebral tract 2, right arrow). D) DC0-like ir (red) and phalloidin staining (green) reveal mb1 and the globular lobe of mb2. E) Detail of mb1. F) Detail of mb2 and its thin peduncle (arrow) which originates from lateral Kenyon cells and closely passes by the calycal glomeruli (asterisk). Scale bars: A, B, E, F: 20 μm, C: 10 μm, D: 50 μm.
Mentions: Small protocerebral lobes (lal, lateral accessory lobes) are connected to the central body (Figure5B), and probably to each other, by a small neurite bundle directly in front of the central body. Anterior of each lal lies the antero-lateral protocerebrum (alp) of the respective hemisphere (Figures2,4 and5B). The alp is intimately connected with the lal, as well as with the remaining protocerebrum and the tritocerebrum.

Bottom Line: In the past decade neuroanatomy has proved to be a valuable source of character systems that provide insights into arthropod relationships.In contrast, Archaeognatha completely lack mushroom bodies and exhibit a central body organization reminiscent of certain malacostracan crustaceans.Several hypotheses of brain evolution at the base of the hexapod tree are discussed.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Evolutionary Biology, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria. a.boehm@univie.ac.at.

ABSTRACT

Background: In the past decade neuroanatomy has proved to be a valuable source of character systems that provide insights into arthropod relationships. Since the most detailed description of dipluran brain anatomy dates back to Hanström (1940) we re-investigated the brains of Campodea augens and Catajapyx aquilonaris with modern neuroanatomical techniques. The analyses are based on antibody staining and 3D reconstruction of the major neuropils and tracts from semi-thin section series.

Results: Remarkable features of the investigated dipluran brains are a large central body, which is organized in nine columns and three layers, and well developed mushroom bodies with calyces receiving input from spheroidal olfactory glomeruli in the deutocerebrum. Antibody staining against a catalytic subunit of protein kinase A (DC0) was used to further characterize the mushroom bodies. The japygid Catajapyx aquilonaris possesses mushroom bodies which are connected across the midline, a unique condition within hexapods.

Conclusions: Mushroom body and central body structure shows a high correspondence between japygids and campodeids. Some unique features indicate that neuroanatomy further supports the monophyly of Diplura. In a broader phylogenetic context, however, the polarization of brain characters becomes ambiguous. The mushroom bodies and the central body of Diplura in several aspects resemble those of Dicondylia, suggesting homology. In contrast, Archaeognatha completely lack mushroom bodies and exhibit a central body organization reminiscent of certain malacostracan crustaceans. Several hypotheses of brain evolution at the base of the hexapod tree are discussed.

No MeSH data available.


Related in: MedlinePlus