Figure 1.

Criteria for distinguishing between lobular types. A. H & E stained images of lobules representative of types 1 to 4 (Scale bar = 30 μm). B. Validation of acini count per lobule to distinguish lobule types, identifying type 1 (green) as approximately 10 ± 4 acini per lobule, type 2 (yellow) as approximately 35 ± 5 acini per lobule, type 3 (pink) as approximately 114 ± 10 acini per lobule and type 4 (blue) based on secretory morphology with differences between types 1, 2 and 3 (*P ≤0.0007), but not types 3 and 4 (P = 0.92) (n= >1,700 lobules). C. Number of nuclei per lobule quantitated for lobular types 1, 2 and 3 (*P ≤0.002) and types 3 and 4 (P = 0.23) (n= >230 lobules). D. Number of nuclei per acini evaluated for each lobular type shows no statistical difference (P ≥0.07) (n= > 230 lobules). E. Lobular area distinguishes between lobules types 2, 3 and 4 (*P ≤0.0001) but not between types 1 and 2 (P = 0.11). F. H & E stained sections showing lobule types 1 and 2 occupying approximately the same area (approximately 50,000 μm²) but categorized as different types based on the number of acini/lobule (Scale bar = 90 μm). All error bars represent standard error of the mean (SEM).