Drosophila laminin heterotrimers are expressed in a tissue-specific manner, and both are required for midgut cell migration. (a–f) Wild-type embryos mid-migration (stage 12; a and d), after migration (stage 14; b and e), or after MET (stage 15; c and f). The red e denotes the endoderm, m denotes the mesoderm, and the posterior midgut is delimited by dashed white lines. (a–f) Both Wb and LanA localize to the endoderm/mesoderm border throughout midgut migration and repolarization. (d–f) LanA is also found surrounding the ICP cells as they migrate (d and e, asterisks) and at low levels at the apical surface of the midgut cells (f, arrowheads). (g and h) Stage 12 sna,twi mutant embryos, the posterior midgut is demarked by dashed red lines. Colorimetric readouts of Wb (g′) and LanA (h′) levels on a scale of 0 to 255 (g and h). In the absence of the mesoderm, Wb staining is completely lost from the midgut (h). In contrast, LanA can still be found around midgut cells (h). (i–k) Stage 12 wild-type (i), wb (j), and LanA (k) embryos. Midgut cell migration is delated in both wb (j) and LanA (k) mutants. Arrows point to the tip of the posterior midgut. (l and m) Velocity, directional persistence, and coordination values calculated from videos of wild-type (n = 11), LanB1 (n = 9), wb (n = 7), and LanA (n = 10) mutant embryos. n represents the average of a minimum of 15 cells in one embryo (shown as a dot). Data are presented as mean ± SEM. *, P ≤ 0.05; **, P ≤ 0.01 by unpaired two-tailed t test comparing each individual condition to wild type. One-way ANOVA tests between LanB1, wb, and LanA showed no significant difference in any of the conditions (PMEC velocity, P = 0.81; PMEC directional persistence, P = 0.94; PMEC coordination, P = 0.83; ICP velocity, P = 0.35, ICP directional persistence, P = 0.35, ICP coordination, P = 0.23; see Table S1 for raw data). Confocal images are oriented with the anterior to the left and posterior to the right. Scale bars, 20 µm (a, b, d, e, g, and h), 10 µm (c and f), and 50 µm (i–k).