Isolation of human mammary epithelial cells (HMEC) from breast cancer susceptible tissue. Outgrowth of cells from duct element in upper right corner cultured in a standard dish; most cells spontaneously die during early cell divisions, but a few will establish long-term growth. NASA's Marshall Space Flight Center (MSFC) is sponsoring research with Bioreactors, rotating wall vessels designed to grow tissue samples in space, to understand how breast cancer works. This ground-based work studies the growth and assembly of human mammary epithelial cell (HMEC) from breast cancer susceptible tissue. Radiation can make the cells cancerous, thus allowing better comparisons of healthy vs. tunorous tissue. Credit: Dr. Robert Tichmond, NASA/Marshall Space Flight Center (MSFC).