Fig. 2. msh⁶⁸ M⁺ clones interfere with the development of the notum and wing hinge. Clones were visualized by the f marker. (A) General view of the proximal wing, wing hinge (within the square) and left heminotum of a wild-type fly. (B) Wing with an abnormally wide hinge attached to the scutum and, ectopically, to the scutellum (arrow) of a fly carrying msh⁶⁸ clones. Arrowheads indicate mutant scutellar bristles. (C) A posteriorly displaced wing (compare with A) attached to a thorax with a reduced scutellum (white arrowhead). Positional reference: dorsocentral bristles (red arrowhead). (D,E) High magnification views of a wild-type hinge and the mutant hinge shown in C (area within a rectangle) after mounting of the cuticle. The tegula is marked (t) as a positional reference. Rectangle in A indicates approximate area of the image in D of an unrelated fly. Broken lines indicate approximate borders of clones. Sclerites 1 (arrow) and 2 (arrowhead) are clearly visible in D, but these are absent in E. Red asterisk indicates the position where they would be expected to occur. Red arrowheads indicate ectopic chaetae. Green arrowhead indicates a probable scutellar macrochaeta. dr, wild-type dorsal radius and its clusters of sensilla campaniformia; only a few dorsal radius-like sensilla are seen in E (black arrowhead). (F,G) Lateral and dorsal views, respectively, of ectopic notum structures (arrows), which developed adjacent and just above the wing hinge (red arrowhead). The presence of f macro- and microchaetae indicate that the tissue is mutant for msh and suggests its notal identity. Tegulae (t), scutellum (asterisks) and costa (arrowhead) are marked for orientation. (H,I) Wild-type notum and notum with msh⁶⁸ M⁺ clone(s) that removed macro and microchaetae. White arrowheads indicate positions of missing supraalar macrochaetae in I. Red arrowhead indicates an extra macrochaeta. Asterisks indicate extant dorsocentral macrochaetae. (J) Clone(s) associated with extra scutellar bristles (white arrowhead), an ectopic wild-type bristle (red arrowhead) and disruption of the scutum-scutellar suture (arrow). (K) Frequencies of anomalies (excepting modifications of the bristle pattern) associated with msh⁶⁸ M⁺ clones induced at the indicated developmental times after egg laying. In parenthesis, number of heminota examined with one or more anomalies. Essentially all clones that comprised relatively large regions of the notum displayed one or more of the listed anomalies.