Human breast development

This review presents an atlas of the histology of the normal physiological states of the human breast including prenatal, prepubertal, and pubertal de velopment, adult resting gland, pregnancy, lactation, and postinvolution. T he aim is to produce a pictorial overview of the main stages in development and the common findings in the adult that are considered to be within the range of normality. Unlike inbred strains of animals, in humans it is clear that the chronology of ductal and lobular development is not predictable, either in the fetus, the infant, the peripubertal breast, or the adult. Thi s is probably due to the individual variation in hormone levels both in ute ro and after birth. For many of the developmental time points there are ver y little data available. In this review we indicate the current state of kn owledge of human breast development and some of the main similarities and d ifferences with the rodent, the main animal model. The major phases of grow th and development are described and accompanied by photographs that are re presentative of each stage. Stress is placed on terminology as there is con fusion in the literature. This article is written as an accessory to the co mpanion review on breast cancer.