Abstract
The neglect of research into women's health and female biology has had major impacts for the fields of mammary biology and cancer. A quarter of the way through the twenty-first century, we still lack basic knowledge regarding the formation and function of the organ that gives its name to all mammals, and which provides important health benefits for children and their breastfeeding parent through the creation and delivery of breast milk. In this review, we highlight key similarities and differences in mouse and human mammary glands, and discuss how both systems of investigation are important and necessary to fill outstanding knowledge gaps. We discuss important discoveries that have arisen through mouse models as well as methodological advances that have enabled more widespread investigations in human samples. Finally, we contend that the translatability of mammary gland research requires thoughtful design, careful evaluation and continued review, irrespective of the system of investigation.