Enlarged images of the palatal-nasopharyngeal fold after double labeling for gelatinolytic activity and laminin.

Frontal cryosections at the middle anteroposterior level of E14.5 (A, C, E) and E15.5 (B, D, F) wild type mouse heads were subjected to DQ-gelatin in situ zymography (ISZ; A, B), followed by immunofluorescence labeling for laminin-111 (LN; C, D) on the same section. Merged images are shown in E and F. At E14.5, gelatinolytic activity colocalizes with the epithelial basement membrane at the lateral and palatal side of the fold (arrows). The pattern of gelatinolysis is similar at E15.5, although activity extends into the adjacent mesenchyme and its intensity is considerably increased. p, palatal shelf; n, nasal floor; np, nasopharynx. Bar, 50 μm.