Figure 3. Prostate pathology in 20-week-old C57BL/6 TRAMP x FVB male mice captured at 40X magnification.

(A) Grade 1, low-grade PIN. There is focal hyperplasia of prostate epithelial cells resulting in stratification of cells (arrow). Hyperplastic cells have increased basophilia and increased nuclear to cytoplasmic ratios. (B) Grade 2, moderate-grade PIN. Hyperplastic epithelial cells form increased numbers of short and tall papillary projections that extend into the glandular lumen. (C) Grade 3, high-grade PIN. There is loss of prostate glandular lumina due to the presence of numerous hyperplastic prostate epithelial cells that project into the lumen and form a cribiform pattern. Hyperplastic cells do not invade the connective tissue that separates the glands into distinct lobules (arrows). (D) Grade 5, Well-differentiated adenocarcinoma. Well-differentiated neoplastic cells form tubular or glandular like structures that have obliterated lobular architecture by invasion of the connective tissue borders; lobules cannot be observed in this photomicrograph as compared to photomicrograph C. Necrosis of neoplastic cells is absent. (E) Grade 6, Moderately-differentiated adenocarcinoma. Neoplastic prostate epithelial cells are attempting to form glandular structures. Glandular structures vary in size and shape. Cellular atypia is increased and necrosis is present (asterisks). (F) Grade 7, Poorly-differentiated carcinoma. Neoplastic cells have marked atypia and are arranged in sheets with no attempt at forming glandular or tubular structures as compared to figures D and E.