Single-Cell Analysis in the Mouse and Human Mammary Gland.

The mammary gland is a complex organ, host to a rich array of different cell types. As the only organ to complete its development in adulthood, it delicately balances both cell intrinsic and external signalling from hormones, growth factors and other stimulants. The gland can undergo vast proliferation, restructuring and functional maturation during pregnancy and undo these gross changes to a nearly identical resting state during involution.