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Mammary Gland

Like other organs in the female reproductive system, the mammary gland responds to hormonal changes with marked structural structures. 

(Note that normal breast tissue is mostly adipose; glandular tissue typically comprises only a small proportion of a breast.)

In the inactive state, mammary gland tissue appears to consist of ducts only, separated by extensive fibrous and adipose connective tissue stroma.  Adipose tissue is concentrated between lobules.  

During pregnancy and lactation, the ducts extend and their secretory ends enlarge.  Secretory cells acquire large, lipid-containing vesicles that resemble mucous cells (although the secretory product is milk, not mucous).  Organization is not as precise (no neat alveoli) as in most other large exocrine glands.

Myoepithelial cells surround the secretory units and, under neural stimulation, forcibly expel their contents.

Bands of smooth muscle may be found in subcutaneous breast tissue, especially in the vicinity of the nipple.

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SIUC / School of Medicine / Anatomy / David King
Last updated:  20 May 2022 / dgk