The formation of differentiated glandular structures depends on the culture medium and cell line. A. Lumen delineated by ZO-1 as shown by immunohistochemistry (reddish-brown) in a mammary acinus and an alveolus from tissue biopsy sections. Hematoxylin staining indicates the position of the nuclei (blue). The drawing indicates the location of basal and apical poles in the glandular structure (nuclei are represented by filled black circles). B. Immunostaining for basal (laminin 332) [red], α6-integrin [α6-integrin; green]) and lateroapical (ZO-1 [green]) markers in acini formed by S1 cells in 3D culture. [Note: in vivo, the contact between luminal cells and the BM in the mammary gland is discontinuous and occurs where myoepithelial cells are not covering luminal epithelial cells . In contrast, in vitro, contact with the BM occurs all along the basal surface of the luminal cells , therefore the α6-integrin staining is all around the acinus]. C. Microinjection of nondiffusible Rhodamine-Dextran (red) fluorescent dye in individual cells of acini formed by S1 cells in 3D culture. D. S1 and MCF10A cells were cultured for 15 days in 3D-Matrigel™ drip either in the H14 medium or the assay medium. Shown is the percentage of multicellular structures with apically polarized ZO-1 (Additional Table S1 with P values - see Additional file 1). Also shown is an example of ZO-1 staining in structures lacking apical polarity formed by MCF10A cells in 3D culture (arrowheads point to the basal location of ZO-1 at certain cell-cell junctions). ND = nondetected; size bar, 5 μm; *P < 0.05; **P < 0.01.
Plachot et al. BMC Biology 2009 7:77 doi:10.1186/1741-7007-7-77