Figure 3. Expression of S-IgA, salivary -amylase, MUC5B, and MUC7 during the first year of infancy. Whole saliva was collected at monthly intervals, and expression patterns were determined by Western blotting. Sample blots from single infants are depicted for S-IgA -chain (A), -amylase (C), MUC5B (E), and MUC7 (G). The arrow indicates the age of first tooth emergence. Blots from different infants were analyzed by densitometry, and signal intensities are depicted for S-IgA blots (six infants) (B), -amylase blots (seven infants) (D), MUC5B blots (four infants) (F), and MUC7 blots (four infants) (H). Closed circles represent median signal intensities. Error bars indicate the 25% and 75% quantiles. The curves (solid lines) were deduced by regression analysis of median signal intensities of S-IgA (r² = 0.42), -amylase (r² = 0.71), and MUC7 (r² = 0.94) vs. age, respectively. Arrows indicate first tooth emergence of each respective infant.