LOBULOALVEOLAR DIFFERENTIATION IN MOUSE MAMMARY TISSUES IN VITRO.

Administration of lobuloalveolar mammogenic hormones (for a period insufficient to induce alveolar differentiation) to immature mice prior to cultivation of their mammary glands in chemically defined, hormone-supplemented media resulted in lobuloalveolar growth in vitro comparable to that of late pregnancy. No such growth occurred in cultures of mammary tissues from mice not treated with hormones. The use of tissues from hormone-treated donors might serve as a valuable tool for studies concerned with differentiation in vitro.