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Mushroom Body Evolution - Figure 9 |
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Figure 9: Mushroom bodies across taxa can be derived from developmental stages of a basal archetype. Figure 9: Mushroom bodies across taxa can be derived from developmental stages of a basal archetype. In basal neopterans, such as cockroaches, mushroom bodies develop incrementally. In Periplaneta, a laminar subdivision or module is added to the pedunculus and lobes at each instar. From the 1st to 4th instar, subdivisions are of unequal width, as shown diagrammatically in the second column to the left. Cross sections of adult mushroom bodies in different insect groups show subdivisional organization similar to one of the early instars of the developing cockroach mushroom body. It is proposed that different types of mushroom bodies have evolved by arrest of the developmental program at different stages of the phylogenetic basal archetype. The lower diagram shows the first appearance of novel mushroom body structures, mapped onto an insect phylogeny.
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