Fig. 2.

Disc eversion defects are associated with lack of BM degradation. (A–C) Confocal cross-sections of wild-type pupae. F-actin, nuclei, and BM are labeled with phalloidin (red), DAPI (blue), and Viking-GFP (green in Top and white pseudocolor in Middle), respectively. (A) During eversion, PS cells and the larval epidermis appose through their basal sides. (B) BM of both epithelial sheets degrades as eversion progresses. (C) This degradation precedes the invasion of the larval epidermis by the PS cells. The bottom panels schematically represent the tissues involved. (D–H) At 6 h APF, a time when disc eversion is complete in wild-type animals and BM is degraded, pupae that failed to evert their discs still present BM at the region where disc eversion takes place (yellow arrowheads). Arrowheads denote the presence (solid arrowheads) or absence (hollow arrowheads) of BM between the PS cells and the larval epidermis.