Mushroom Body Evolution

Mushroom Body Evolution - Figure 6

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Figure 6: Mushroom bodies of annelids (lophotrochozoan) are similar to those of insects (ecdysozoans). A. In the scale worm Arctenöe vittata, the mushroom body pedunculus (ped) is capped by many thousands of globuli cells. Its pedunculus and single lobe receive inputs from the olfactory lobe (olf lob). B. The apterygote Thermobia (firebrat) has a divided vertical lobe (V1, V2) and five glomerular medial lobes (1-5) flanking a smaller lobe in the middle (M). C. The medial lobes of the humming bird moth Hemaris thisbe are elaborately subdivided with the gamma lobe lying alongside the vertical lobe (V). Like in other Lepidoptera, the medial lobe is subdivided into many components, here designated b., d., q with satellite neuropil (sat) provided by small bundle of Kenyon cell axons (not in plane of section). D. The medial lobe of the fleshfly Sarcophaga carnaria, like Drosophila (Ito et al., 1998), does not show obvious division into separated gamma and beta components. E, F. In the horsefly Tabanus, the medial lobes show complete terminal separation of the beta and gamma components and the vertical lobe (F) is deeply divided into two components, alpha and alpha prime. The spur (s) is an outgrowth of the junction of the pedunculus with the vertical and medial lobes. In this tabanid, the spur is divided into three components. G. The vertical and medial lobes of the tettigonid Scudderia furcata, like those of many other orthopterans, show striking longitudinal zonations. A dense band of Kenyon cells (arrow) is flanked by two parallel divisions M1, M2, corresponding to V1, V2 of the vertical lobe. H, I. The vertical (V) and medial lobes (M) of a predatory tiger beetle (Cicindelidae) are proportionally as large as those of the water beetle Dytiscus marginalis (I), although the latter has a greatly reduced calyx. Note the extrinsic neuron axons (arrow) leaving the distal end of the vertical lobe. The pedunculus (ped) of each is sectioned obliquely to show two parallel divisions (dashed lines in H, I) comprising thick and thin Kenyon cell axons. Scales in A, G, H, I = 50 µm; Scales in B-F = 100 µm. The midline in B, F, is indicated by an arrow, m.

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