Nrp2b is required for correct guidance of NC cells and corneal endothelium formation.

(A-B) NC cells (green) that migrated into the distal side of the eye form a NC-free area over the lens delineated by leading edge cells forming an open ring structure (stippled white line). Note that NC cells are absent in the ventral aspects of the distal eye at 40 hpf in the embryos injected with a control morpholino (A, n = 14 embryos). Upon nrp2b morpholino knock-down (KD), the NC-free area over the lens became smaller (B, stippled white circle; n = 17 embryos) with ectopic NC cells in the ventral part of the distal eye (arrow). Orientation: nasal (N), temporal (T), dorsal (D) and ventral (V). (C-D’) At 5 dpf the corneal endothelium (grey) forms a monolayer of cells over the lens, which appear surrounded by a ring of annular ligament cells (stippled magenta circle) in en face views (C-D). (C’-D’) Corresponding transverse section views along the nasal-temporal axis of a control and nrp2b-KD embryo shown in C-D. Stippled double-head arc arrows (magenta) show the extent of the corneal endothelium. Scale bar: 50 μm (E) Corneal endothelial cells of control embryos at 5 dpf are composed of 25.3 ± 3.8 cells (n = 22), whereas those of nrp2b-KD embryos are 4.8 ± 2.7 cells (n = 28). ***Welch Two sample t-test p-value<2.2 x10^-16 (t = 20.9, df = 36.3).

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