Fig. 1

Histopathological evaluation of an intraductally transplanted model of DCIS (MCF10A_DCIS). Two weeks post-implantation (a, b), solid-type intraductal growth of MCF10A_DCIS cells showed no staining with an antibody targeted at mouse Ki-67 but positive staining with an antibody targeted at the human protein (a, brown stain). DAPI staining (a, b, blue) identified both human and mouse epithelial cells whereas a FISH probe for human centromeres (b, red) identified cells of human origin on an autofluorescent (green) tissue background. Histopathology of DCIS lesions 8 weeks post-implantation (c, d); cribriform architecture of a MCF10A_DCIS xenograft (c); comedo-type necrosis in a MCF10A_DCIS xenograft lesion (d, arrowheads), with central necrotic areas. Comedo-necrosis type features of MCF10A_DCIS xenografts 8 weeks post-implantation (e, f); comedo-type DCIS-like (e, arrowheads) and invasive (e, arrows) structures on H&E; corresponding TUNEL staining (f), showing viable (gray) and necrotic (brown) regions of tissue. Scale bars = 200 μm (a, b); 350 μm (c, d); 800 μm (e, f)