Editing Breast (section)

===Glandular structure===
{{Main articles|Mammary gland}}
[[File:Normal breast histology.png|thumb|Normal [[histology]] of the breast.]]

The breast is an [[apocrine]] gland that produces the [[Breast milk|milk]] used to feed an infant. The [[nipple]] of the breast is surrounded by the [[areola]] (nipple-areola complex). The areola has many sebaceous glands, and the skin color varies from pink to dark brown. The basic units of the breast are the terminal duct lobular units (TDLUs), which produce the fatty breast milk. They give the breast its offspring-feeding functions as a mammary gland. They are distributed throughout the body of the breast. Approximately two-thirds of the lactiferous tissue is within 30&nbsp;mm of the base of the nipple. The terminal lactiferous ducts drain the milk from TDLUs into 4–18 lactiferous ducts, which drain to the nipple. The milk-glands-to-fat ratio is 2:1 in a lactating woman, and 1:1 in a non-lactating woman. In addition to the milk glands, the breast is also composed of connective tissues ([[collagen]], [[elastin]]), white fat, and the suspensory Cooper's ligaments. Sensation in the breast is provided by the [[peripheral nervous system]] innervation by means of the front (anterior) and side (lateral) cutaneous branches of the fourth-, fifth-, and sixth [[intercostal nerves]]. The T-4 nerve ([[Thoracic spinal nerve 4]]), which innervates the [[dermatomic area]], supplies sensation to the nipple-areola complex.<ref name=grabowski>{{cite book |first1 = Gerard J. |last1 = Tortora |first2 = Sandra Reynolds |last2 = Grabowski |title = Introduction to the Human Body: the Essentials of Anatomy and Physiology |date = 2001 |publisher = J. Wiley |location = New York; Toronto |isbn = 978-0-471-36777-2 |edition = Fifth. }}</ref>