Neuroarchitectures Serving Compound Eyes of Crustacea and Insects

Acetylcholine in the crayfish optic lobe: concentration profile and cellular localization

“…5 and 6, ME and MI) and course parallel to the long axis of the eyestalk. Previous studies (Strausfeld and Nassel, 1980) indicate that transmedullary neurons give rise to dense but narrow field (1 O-l 5 Frn) dendritic projections. The extremely fine dendrites illustrated in Figure 4A did not reproduce in the photomicrographs, but the origins of these dendrites can be seen as protuberances on the monopolar cell axons in Figure 6, ME, MI.…”

“…Figure 5 (inset) and Figure 6 reveal the pattern of lamina reactivity as observed with peroxidase and FITC conjugates, respectively. Tangential cells originate proximal to the lamina in the medullary cell body area (Wang-Bennett and Glantz, 1987b) and the centrifugal cells arise on the proximal side of the second optic ganglion, the medulla externa (ME) (Strausfeld and Nassel, 1980). The tracings on the top of Figure 4A and the processes in Figures 5 and 6 (all from different preparations) indicate a terminal arbor several columns wide and distal to the lamina plexiform.…”

“…Right side is dorsal. B, Reconstruction of a horizontally sectioned optic lobe immune reactive neurons in ME, MI, and the proximal medulla terminalis (MT and T-neurons (about 10 Frn diameter) (Strausfeld and Nassel, 1980;Wang-Bennett and Glantz, 1987b). The most reactive sites in the optic lobe are the medulla externa (ME) and the medulla interna (MI).…”

“…The structure and location of the immunoreactive cells in the medulla externa and interna indicate that they are transmedullary monopolar neurons, i.e., a subset of the columnar neurons of the second and third optic neuromeres (Strausfeld and Nassel, 1980). The identification is based upon the location of the cell bodies at the distal edge of the medulla, the orientation of the axons parallel to the long axis of the eyestalk, and the relatively narrow field (1 O-l 5 pm) of processes in the medullary neuropile.…”

“…In each ganglion, the transverse dendrites of multicolumnar neurons intersect the columnar projection in a 3-dimensional grid. In several insects (particularly in diptera) and crustaceans, the synaptic connections between a number of the identified cell classes have been described morphologically (Strausfeld and Nassel, 1980). More recently, the physiological characteristics of the neurons in the first 2 optic neuromeres in crayfish have been documented (Kirk, 1982;Waldrop and Glantz, 1985a, b;Wang-Bennett and Glantz, 1987a, b).…”