Figure 1. Co-expression of osteopontin and MMP-3 in human and mouse salivary glands. Immunolocalization (brown = 3,3'-diaminobenzidine, DAB; blue = hematoxylin counterstain) and in situ (blue stain, BCIP/NBT, with or without fast-red counterstain) in human (A-F) and mouse (G-L) paraffin sections. Staining of different but representative sections of human parotid ducts at low magnification (A) and high magnification (B) with OPN antibody (LFMb-14). Note the non-staining ‘basal’ cells (black arrow). Panel (F) is a representative IgG control. OPN antisense staining of human submandibular ducts (C). All human ducts are also positive with antibody (D) and antisense (E) to MMP-3. Note that MMP-3 message is weak or absent from the ‘basal’ cells of the striated ducts (panel E, black arrows). In contrast, female mouse parotid (G) and submandibular glands (I) stain positive for OPN protein (LF-175) in all ducts as well as parotid serous acini and submandibular seromucous acini, respectively. The message for OPN is also seen in the ducts and serous acini of the female mouse parotid (H). In the mature male mouse, submandibular gland ducts (except for the granular convoluted tubules, GCT noted as *) and the seromucous acini (J) stain for OPN message. Mouse MMP-3 message is similarly distributed in the submandibular ducts and seromucous acini of both sexes, except for the lack of staining in the GCT (male shown, K). Panel (L) is a representative sense strand control. M and S labels represent typical mucous and serous acini, respectively, of human glands. White arrows indicate intercalated ducts. Treatment with proteinase K during in situ preparation destroys the fast-red counterstaining properties of mouse nuclei. Bar: 50 µm.