Fig. 1. col/kn mutant wings: abnormal vein pattern and reduced size. (A) Wild-type wing with the longitudinal L2 to L5 veins indicated. The small arrowhead and arrow point to veins L3 and L4, respectively. (B) col1 /kn1 mutant wing; veins L3 and L4 are closer to each other than in wild-type wing and partly apposed proximally. (C) col1/col1 wing (abbreviated col1 in subsequent figures). L2 and L5 veins are normal, but a central larger L3-type vein is present (L3m vein, large arrowhead), whereas only a small, proximal region of L4 vein forms (vertical arrow). col wings are smaller than wild type, owing to (partial) loss of the region between L3 and L4 veins and a reduced size of the posterior compartment. In addition, col1 wings display a wider L2-L3 intervein than do wild type or col1 /kn1. (D) Schematic superimposition of wild type (grey) and col1 (black) wings adjusted so as to align the proximal L4 vein. All wings are shown at the same magnification.