Effects of transplantation of Slit-expressing cells on the LOT cue. Aggregates of control HEK cells (A, B) and Slit-expressing cells (C–J) were placed on E12.5 telencephalons in thedotted lines, and the telencephalons were organotypically cultured for 2 d in the normal culture media (A–H) or in the presence of RoboN (I, J). A,C, E, G, I, Lot cells visualized with mAb lot1 (red).B, D, F, H,J, Mitral cell axons visualized with anti-neuropilin-1 antibody (green). The left andrightpanels in each roware identical fields. In C and D, mitral cell axons are repelled by Slit-expressing cells and grow back into the olfactory bulb (arrows). In E andF, mitral cell axons are repelled for a short distance (arrows) but are still confined to the area delineated by lot cells (arrowheads). In G andH, once mitral cell axons grow out of the olfactory bulb, they always follow the LOT position at which lot cells align (arrowheads), although these axons often stall halfway along (arrows). In I andJ, the repulsive effect of Slit is inhibited by RoboN. Scale bar, 500 μm.