Dm4 [FBbt_00003771]

Dm4

ID: FBbt_00003771

Distal medullary wide-field amacrine neuron whose cell body is located in the anterior region of the cell body rind of the medulla. The main neurite extends into M6, and then turns back to arborize in the boundary between M5 and M6, and in M3B, with mixed morphology arborizations. The arbor varies in shape between cells, covering around 21 columns, but with these areas tiling. It is located in a central position in the column, surrounded by the terminal of photoreceptors R7 and R8, with the cell boundaries following the column boundaries. There are around 40 Dm4 neurons per hemisphere. They are glutamatergic (Davis et al., 2020).

Classified as columnar based on first stretch of main projection being limited to a single column, but as it then bends and projects along the plane of M5/M6 where it arborizes, this is clearly an edge case. Pre- versus postsynaptic innervation were judged by scoring of terminal morphology from figures in Fischbach and Dittrich (1989) as assessed by FlyBrain Neuron DB.