It is very difficult to study the human mammary gland, and although mouse models are widely used in research they do not provide a very accurate depiction of the human mammary gland. We have developed a model in which human mammary cells placed in collagen form structures resembling the mammary gland in vivo (organoids). These organoids were stained with markers specific to different cell types typically seen in the mammary gland. In these images one can see a distinct separation of an outer and inner layer of cells. The organization of these different cell types in the organoids mimicked what is observed in the human mammary gland.