A variety of retinotopic transmedullary (Tm) cells receive inputs at various levels in the medulla (Me) and provide outputs in the lobula. Here are two examples of Tm cells that show motion- sensitive, but not motion-specific responses. Tm9 (A) was intracellularly stained with lucifer yellow. The preparation was subsequently stained with propidium iodide to reveal locations of cell bodies. Dendrites of Tm9 extend across at least two retinotopic columns, and the lobula endings lie entirely within the T5 dendritic layer. Its responses to directional grating motion (B) consisted of non-direction-sensitive fluctuations in phase with the contrast frequency of the grating. Responses of Tm1b (C,D) were similare, but lacked a hyperpolarizing component. 3-D rotation of the confocal stacks reveals four recurrent branches in the outer medulla (D, right inset) within three neighboring retinotopic columns (D, left inset). Me, medulla; Lo, lobula; cb, cell body. Scale bars: (A and D) 20µm. See Douglass and Strausfeld (1998) for additional information.