What are breasts?

Breasts are part of the female and male sexual anatomy. For females, breasts are both functional (for breastfeeding) and sexual (bringing pleasure). Male breasts don’t have a function. The visible parts of breast anatomy include the nipples and areolae.

What are breasts made of?

Several kinds of tissue form female breasts. Muscles connect breasts to ribs, but they aren’t part of the breast anatomy. The different types of breast tissue include:

  • Glandular: Also called lobules, glandular tissue produces milk.
  • Fatty: This tissue determines breast size.
  • Connective or fibrous: This tissue holds glandular and fatty breast tissue in place.

What parts make up breast anatomy?

There are many different parts to female breast anatomy, including:

  • Lobes: Each breast has between 15 to 20 lobes or sections. These lobes surround the nipple like spokes on a wheel.
  • Glandular tissue (lobules): These small sections of tissue found inside lobes have tiny bulblike glands at the end that produce milk.
  • Milk (mammary) ducts: These small tubes, or ducts, carry milk from glandular tissue (lobules) to nipples.
  • Nipples: The nipple is in the center of the areola. Each nipple has about nine milk ducts, as well as nerves.
  • Areolae: The areola is the circular dark-colored area of skin surrounding the nipple. Areolae have glands called Montgomery’s glands that secrete a lubricating oil. This oil protects the nipple and skin from chafing during breastfeeding.
  • Blood vessels: Blood vessels circulate blood throughout the breasts, chest and body.
  • Lymph vessels: Part of the lymphatic system, these vessels transport lymph, a fluid that helps your body’s immune system fight infection. Lymph vessels connect to lymph nodes, or glands, found under the armpits, in the chest and other places.
  • Nerves: Nipples have hundreds of nerve endings, which makes them extremely sensitive to touch and arousal.

What about the male breast?

Males have breasts, too. During puberty, the male hormone testosterone usually stops breasts from developing like a female’s. On the outside, males have nipples and areolae. Internally, they have undeveloped milk ducts and no glandular tissue. Male breast problems can include gynecomastia, a benign condition that causes the breasts to enlarge, and very rarely, breast cancer.

What are dense breasts?

Your mammogram report may note that you have dense breasts. Dense breasts have more glandular and fibrous tissue and less fatty tissue. Dense breast tissue and tumors both look white on mammograms, making it more difficult to detect breast cancer. Up to half of women between the ages of 40 and 74 have dense breasts. The condition isn’t related to breast size, look or feel. Women with very dense breasts have a slightly higher risk of breast cancer.

How do breasts work?

Female hormones — namely, estrogen, progesterone and prolactin — play a key role in breast development and function.

  • Estrogen stretches milk ducts and helps them create side branches to carry more milk.
  • Prolactin promotes the production of progesterone and prepares glands for milk production.
  • Progesterone increases the number and size of lobules in preparation for breastfeeding. This hormone also enlarges blood vessels and breast cells after ovulation. You may experience swollen, tender breasts.

What conditions and disorders affect breast anatomy?

Breast cancer is the number one threat to breast health. Approximately 1 in 8 women will receive a breast cancer diagnosis in her lifetime. Other conditions that affect breast health include:

How can I keep my breasts healthy?

Since breast cancer is a top concern, talk to your healthcare provider about when and how often to get mammograms. Recommendations vary depending on risk factors, such as family history of disease. Breast self-exams can help you get familiar with how your breasts look and feel so you more easily notice changes or potential problems.

When should I call the doctor?

You should call your healthcare provider if you experience:

  • Newly discovered lump.
  • Nipple discharge.
  • Breast pain.
  • Changes in the way your breast or skin looks or feels.
  • Nipple that suddenly turns inward (inverted nipple).
  • Breast rash.

A note from Cleveland Clinic

Female breasts can produce milk for breastfeeding and also serve as an erogenous (pleasure) zone. Different types of tissues form the breasts. These tissues can become cancerous. Regular mammograms, or breast screenings, can help detect cancer early when it’s most treatable. Call your healthcare provider anytime you notice a change in the way your breasts look or feel.

Care at Cleveland Clinic

Last reviewed by a Cleveland Clinic medical professional on 10/14/2020.


  • National Breast Cancer Foundation. Breast Anatomy. (https://www.nationalbreastcancer.org/breast-anatomy) Accessed 10/15/2020.
  • National Cancer Institute. Breast Anatomy. (https://training.seer.cancer.gov/breast/anatomy/) Accessed 10/15/2020.
  • Susan G. Komen. Breast Anatomy. (https://ww5.komen.org/BreastCancer/TheBreast.html) Accessed 10/15/2020.

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