Time course of specimen W (MZL) xenograft development demonstrates abrupt plasma cell differentiation between 1 and 2 weeks. A total of 1 × 107 cells of specimen W were implanted in each of 6 mice; 2 mice were harvested at 7, 14, and 30 days (H&E stained). By day 7, T cells (CD2+) were more abundant in the graft than in the original specimen, and B cells (CD20+) were relatively less abundant. Plasma cells (CD138+) appeared between days 14 and 30. In contrast to specimen J, the CD20+ cells of specimen W coexist with the CD138+ forms. Furthermore, there was a consistent peripheral distribution of the plasma cells (see day 30, CD138). By day 30, the Ki67 appears to be decrementing. Tissue marked with asterisks are pancreas; original magnification of all images ×40.
