Although milk production (lactation) is one of the defining features of mammals, such as mice and humans, we know relatively little about how milk is made. To find out what’s going on, researchers have developed a technique called intravital imaging to look inside living animal tissues. These strange green shapes, squirming under the microscope, are cells in a milk duct in the mammary gland of a live female mouse. The red blobs are fat droplets – one of the major components of milk. Following injection with oxytocin (a hormone that encourages lactation), fat droplets are released from cells in the ducts, with smaller droplets fusing together to create larger ones. Then they’re squeezed out of the duct by muscular contractions. This technique opens a window on the mysterious process of milk production, and could help to explain what happens when human mums struggle to produce enough milk to feed their babies.
Written by Kat Arney
BPoD stands for Biomedical Picture of the Day. Managed by the MRC London Institute of Medical Sciences the website aims to engage everyone, young and old, in the wonders of biomedicine. Images are kindly provided for inclusion on this website through the generosity of scientists across the globe.