FIGURE 3.

Lamina development including the migration of epithelial and marginal glia, and lamina wide-field neurons (Lawf). (A) Schematic of the lateral view of the third larval instar optic lobe. Developing photoreceptors project to a fold in the outer proliferation center neuroepithelium called the lamina furrow and induce lamina formation. (B) Diagram of a cross-section along the dotted line in A. The developing lamina forms in characteristic columns. Seven lamina precursor cells are incorporated into each column. Epithelial and marginal glia migrate above and below photoreceptor growth cones. Lawf neurons share the same progenitors as epithelial and marginal glia; they migrate from their point of origin at the tips of the lamina to the medulla, where they stop immediately adjacent to the neuropil. (C) Two timepoints extracted from Movie 3 of a cultured R27G05 > 20xmcherry (magenta) and Ecad::GFP (cyan) brain (wL3) showing the lamina, photoreceptor axons and surrounding tissue. The lamina furrow is marked by a dashed line. The lamina grows considerably over ∼18 h as indicated by the bracket. Timescale displayed as hh:mm:ss, scale bar = 20 μm.