Fig. 6. Expression of vestigial in normal wing discs and TD leg disc cells.
(A) The endogenous expression patterns of wg and dpp in the wing disc during the second and early third larval instars. vg (cross-hatched) is expressed where wg and dpp signals intersect and is required for proper wing and haltere development (Williams, Bell, & Carroll, 1991). (B) The left leg disc in the panel depicts the endogenous expression patterns of wg and dpp. Upon ubiquitous wg expression (right leg disc in panel), dpp expression is repressed throughout the entire leg disc, except for the proximal-most dorsal region (weak point) leading to ectopic activation of vg (cross-hatched) and TD to wing. The figure is adapted from (Wei et al., 2000).