Figure 9. Filopodial interactions lead to interlacing of tip cells.

(Left) Depth coded 3D rendering of limbal region of a P2.5 eye shows four tip cells interlacing with each other in the future SC plane. (Right) Magnification of the region within the white box in the left panel shows a cluster of interacting tip cells ranging in colors from cyan to violet. The complex LVP is in magenta. Superficial Z-slices were removed digitally in Imaris to reveal the interlaced tip cells with greater clarity. In this view, it is clear that each of the pseudocolored tip cells is connected to its own sprout and these sprouts connect to the LVP. Although the cell borders cannot be always unambiguously ascertained with endomucin staining, the fact that four individual sprouts are connected to this cluster clearly indicates that it originated from at least four tip cells. (Bottom) The sprouts and cells have been pseudocolored for clarity (numbered 1–4). The tissue that is not pseudocolored does not connect to this cluster. Cartoon represents the interlacing of tip cells. For simplicity, RV and their sprouts are not shown, and this in no way is meant to suggest lesser importance of RV. The 3D coordinates are shown. Scale bar, (Top Left) 20 µm and (Top Right and pseudocolored image) 10 µm.