Figure 4

Immunohistochemical localization of S100P protein in normal human tissues. Panel A shows the staining reaction obtained by new 18-9 MAb in the placenta. Commercial control S100P antibody has been used in the panel B. Both antibodies immunostain trophoblast cells (arrowheads in the inset) lining the placental villi. Other panels demonstrate the distribution of S100P protein in the human gastric mucosa (C,D,E), esophagus (F), liver (G) and pancreas (H). The staining reactions are strong in the stomach, distinctly weaker in the esophagus and negative in the liver and pancreas. In the stomach, the most prominent signals were located to the mucus secreting epithelial cells. Positive reactions were also present in the principal cells (small arrows) of the gastric glands (GL). The parietal cells were negative or only weakly stained (small arrowheads). The large arrows in panel E point to the intestinal metaplasia that was occasionally seen in some specimens as a benign pathological change within the gastric mucosa. In panel F, the arrowheads indicate some positive nuclei in the esophageal epithelium. EN = endocrine pancreas, EX = exocrine pancreas.