The article gives an overview of the development of the mammary glands in sows. Starting from the prenatal phase, the developmental phases up to the first suckling period, the genetic, anatomical, endocrinological and nutritional aspects are discussed. The influence of body condition in prepuberty, at the time of puberty, at the first mating use, during pregnancy, especially the last trimester, and during the first lactation will be discussed. The nutritional intensity in the various phases of rearing, prepuberty and during the first gestation proves to be an important exogenous factor for good mammary gland development in the sows. The development of the mammary gland is closely related to that of the subcutaneous fatty tissue. The parenchymal tissue in the udder is particularly affected. A temporary feed restriction followed by a compensatory feeding phase during rearing and pregnancy has a detrimental effect on the development of the parenchymal tissue of the mammary glands in gilts and sows.