To build the model mammary gland tissue was obtained from patients who let reduce their breast. After certain enzymatic steps the researchers prepared single cell suspensions. The individual cells were cultivated in a transparent collagen I gel adherent or floating, where they proliferated, spreadout  and began to form the three-dimensional architecture of a mammary gland, similar to those developing in the time of puberty. The mammary gland has branched ducts terminating in tiny, milk producing pockets. Outwards the strands are combined to a duct which and in the nipple. During the menstrual cycle and during a pregnancy the proliferation of cells and a remodeling of the ducts occure. Adult stem cells are able to develop to a full breast.

Such an in vitro breast organoid assay can be used  as regeneration assay for identifying and quantifying of cells with regenerative potential or to study cell interactions with the environment.

Source:
https://www.helmholtz-muenchen.de/en/news/press-releases/2015/press-release/article/26999/index.html

Original Publication
Linnemann, JR. et al. (2015). Quantification of regenerative potential in primary human mammary epithelial cells, Development, DOI:10.1242/dev.123554 http://dev.biologists.org/content/early/2015/06/09/dev.123554.abstract