Figure 2.

Tissue sections of human parotid and submandibular salivary glands. Ducts are marked with an asterisk. (A) Cell membranes of adherens junctions (E-cadherin [E-cad]) and tight junctions (ZO-1) are seen in both acinar and ductal epithelial cells. E-cad is present in the lateral membranes between the cells, while ZO-1 is restricted to the apical surface of the acinar cells and limited to the subapical region in ductal cells. MUC1 and SCRIB are readily visible in ductal cells but not well detected in the acini. There is strong membrane staining and weak cytoplasmic staining for PAR3, a protein found in the partition complex, for both ductal and acinar epithelial cells. Asterisks identify ductal compartments. Scale bar is 50 µm. (B) MIST1 staining is seen in the nuclei of acinar cells in the parotid gland. Aquaporin-5 (AQP5) staining of MIST1⁺ acinar regions in the parotid (red) shows the “chicken feet” pattern while no staining of ducts is seen. Staining for MUC1 (green) demarcates the luminal surface of ducts in tissue with no visible stain seen in the acinar regions. SCRIB staining in ductal cells clearly reveals the ductal population (image contributed to National Institutes of Health Image Gallery). Scale bars are 20 µm. (C) MIST1 staining is seen in the nuclei of acinar cells in the submandibular gland. AQP5 staining demarcates the luminal surface of the acinar cells as in the parotid without signal in the ducts. Both MUC1 and K19 clearly stain only the ductal cell populations.