Comparison of Tumor tissue morphology in vivo with Explants grown in vitro. In Vivo H&E (Top panel) is Hematoxylin and Eosin staining of the primary tumor lesion used for generating explant cultures and shows tumor cell nests in a fibrofatty matrix within the breast stroma taken with a 10× objective (left) and 25× objective (right). In Vitro Phase Contrast photomicrographs (Middle Panel) depict the growth and morphology of MAM-1 explant cultures in vitro. Photomicrographs were taken with a (10×, left) or (20×, right) objective. Note in particular the morphological similarities between the explants grown in vitro and resemblance to the tumor in vivo. In Vitro Immunofluorescence (Bottom Panel) of MAM-1 grown on coverslips and dual-stained for HER2/neu (FITC, green) and α-SMA (TRITC, red) and counterstained for DAPI depicting the nuclei in blue. HER2/neu staining is strong and specific for tumor cells while α-SMA staining is exclusively associated with the cells surrounding the tumor cell nests and localized to the actin-based cytoskeleton. Asterisk depicts nucleus of stromal cell for orientation.