Fig. 5. Tracheal terminal cell expression and mutant phenotype of myospheroid integrins. (A-B') Confocal fluorescent images of tendrils⁺ (A) and tendrils^13-8 (B) terminal cell clones in larva fillets stained with mAb CF6G11 to show ß_mys-integrin (red) and with anti-GFP (green) to show terminal cell cytoplasm. A' and B' show ß_mys staining in gray scale. ß_mys is found at higher levels in the periphery (arrowhead) of tendrils⁺ but not in tendrils^13-8 terminal branches. Terminal branches adhere to muscles that also express ß_mys. Bright ß_mys staining in B (asterisk) is outside the tracheal system. (C-G) Fluorescent images and brightfield close ups (C'-G') of wild-type and homozygous DB terminal cell clones of integrin pathway mutations indicated. (C,C') Wild-type control. (D,D') rhea⁷⁹, (E,E') mys^XG43, amorphic ß_mys-integrin allele. (F,F') mys^G4, point mutation that disrupts ECM-binding by ß_mys (Jannuzi et al., 2002). (G,G') mew^M6, if^k27e double mutant. mys (E,F) and mew if (G) phenotypes are similar to tendrils phenotype (D). (H,I) mys^XG43 DB terminal cell clone imaged in early L3 and again 48 hours later as in Fig. 3D-G. Terminal branches are lost and there is an increase in lumen density and complexity in remaining branches, as in tendrils mutants. Specific terminal branches are numbered; dots indicate distal extent of lumens. After 48 hours, branch 5 has been lost, branches 1-4 (broken lines) are barely detectable and their lumens (dots and arrowhead) have been displaced into the proximal branch, as in tendrils clones (Fig. 3F,G). Lumen displacement is also evident from changes in position of luminal bifurcation (arrowhead) with respect to branches 2 and 3. Panel I is a montage. (J-L) TEM analysis of mys^XG43 DB terminal cell clone as in Fig. 1H-M. Terminal cell contains multiple lumens (red dots) without any intervening basal plasma membranes, as shown by close-up (L). tc, terminal cell; m, muscle; h, hemocyte. Scale bars: in A, 20 µm for A,B; in C, 25 µm for C-G; in C' 25 µm for C'-G'; in I, 25 µm for H,I; 2 µm in K; 0.5 µm in L.