What is "milk line"

n. (context anatomy English) One of two parallel lines on the breast of a mammal along which the nipples are found.

The milk lines are two lines, formed by thickenings of the epidermis (the mammary ridge) along the ventral surface of mammals of both sexes. They extend from the upper limbs (arms) to the lower limbs (legs) and are developed in the embryo. They give rise to the mammary glands and nipples but are otherwise usually not visible in the adult.