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Breast development and morphology

Jose Russo, MD
Section Editor
Anees B Chagpar, MD, MSc, MA, MPH, MBA, FACS, FRCS(C)
Deputy Editor
Wenliang Chen, MD, PhD


The breast undergoes dramatic changes in size, shape, and function in association with puberty, pregnancy, lactation, and menopause. It is also the origin of the most common malignancy in women [1]. The risk of developing breast cancer has been linked to both endogenous (eg, nulliparity, early menarche, older age at first pregnancy) and exogenous hormonal influences [2-5]. (See "Factors that modify breast cancer risk in women" and "Menopausal hormone therapy: Benefits and risks".)

The molecular mechanisms underlying the development of breast cancer, particularly estrogen-associated breast carcinogenesis, are incompletely understood. Increasing evidence points to developmental differences in the breast that may influence the risk of developing cancer. Thus, an understanding of breast development and morphology, and the biochemical factors that influence them, is pertinent to the study of both premalignant and malignant conditions affecting the breast.


The mature adult breast lies between the second and sixth ribs in the vertical axis and between the sternal edge and the midaxillary line in the horizontal axis. Breast tissue also projects into the axilla as the axillary tail of Spence. The breast comprises three major structures: skin, subcutaneous tissue, and breast tissue, which is composed of both epithelial and stromal elements. The epithelial components are branching ducts that connect the structural and functional units of the breast (the lobules) to the nipple (picture 1). The stroma, which comprises the majority of the breast volume in the nonlactating state, is composed of adipose and fibrous connective tissue (picture 2).

The skin of the breast is thin and contains hair follicles, sebaceous glands, and exocrine sweat glands. The nipple has abundant sensory nerve endings and sebaceous and apocrine sweat glands but not hair follicles. The areola is more or less circular and pigmented, measuring 15 to 60 mm in diameter. The Morgagni tubercles, which are located near the periphery of the areola, are elevations formed by the openings of the ducts of the Montgomery glands, large sebaceous glands that represent an intermediate stage between sweat and mammary glands.

The superficial pectoral fascia envelops the breast and is continuous with the superficial abdominal fascia (of Camper). The undersurface of the breast lies on the deep pectoral fascia, covering the pectoralis major and serratus anterior muscles. Connecting these two fascial layers are fibrous bands (the Cooper suspensory ligaments) that represent a natural means of support for the breast.

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Literature review current through: Nov 2017. | This topic last updated: Jun 26, 2017.
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