Estrogen and progesterone receptors can be maintained in normal human breast epithelial cells in primary culture and after transplantation into nude mice

The estrogen and progesterone receptor expression was determined in breast epithelial cells from reduction mammoplasty specimens. Only a subset of the luminal epithelial cell population was found to be positive for these rece ptors. When these cells were subsequently cultured in 3-dimensional collage n gel system (in vitro model) or transplanted into nude mice (in vivo model ), the cells retained their ability to express both receptors in these expe rimental systems. The maintenance of primary normal human breast epithelial cells expressing the estrogen and progesterone receptors in experimental s ystems has not been reported previously.