The epithelial origin of the primary culture cells. (A) Phase contrast micrograph showing epithelial cells derived form the tissue fragment of the breast cancer biopsy. The cells are polygonal and have pleomorphic nuclei with prominent nucleoli. (B) Electron micrograph showing the contact of adjacent epithelial breast neoplastic cells through the formation of tight junctions and desmosomes (arrows) which delineate intercellular lumina (IL) lined by protruding microvilli. N; nucleus. (C) immunofluorescence micrograph of cells from primary culture showing cytoplasmic localization of CK8 with varying intensity. (D) Cells were counterstained with DAPI. (E) Merged immunofluorescence micrographs of cytokeratin 8 localization and DAPI revealing the cytoplasmic localization of CK8 in the entire cell population verifying their epithelial origin. Original magnification: (a) ×400×, (b) ×15,400, (c-e) ×200.