A lot goes into making milk. A lactating breast is described in Gray's Anatomy as, "as being composed of glandular and adipose tissue held together by a loose framework of fibres called Cooper's ligaments." The lobes are made up of lobules, which are groups of clusters of alveoli ( Latin alveolus, "little cavity") containing lactocytes (mammary secretory epithelial cells) that make breastmilk (Tobon & Salazar, 1975; Fawcett, 1986). Alveoli are connected to tiny ducts that join together, forming larger ducts that drain the lobules. These larger ducts merge into one big milk duct for each lobe. Under the areola the one big milk duct widens into a lactiferous sinus (cavity) (Bannister et al. 1995; Vorherr, 1974) before narrowing at the base of the nipple and ending in its own opening on the surface of the nipple. The fatty (adipose) tissue of the breast is typically situated between lobes rather than within lobules.
Anterior pituitary glands make and secrete prolactin. Prolactin is also produced in the breast, brain, uterine lining, parts of the central nervous system and the immune system. One of prolactin's effects is to regulate lactation. Oxytocin, the second hormone involved in milk production, is a neurotransmitter in the brain. Oxytocin acts on the mammary glands, causing milk to be 'let down' into alveoli from where it can be extracted by compressing the areola and sucking at the nipple. Sucking by the infant at the nipple is relayed by spinal nerves to the hypothalamus.
The specifics of lactating and exactly how the breast works can be a lot to absorb when you are actually in the thick of it, sleepless, with a new baby. Come to your local Le Leche League meeting in Bedford, NH on the second Friday of each month at 7 pm or on the fourth Friday of each month at 1 pm. For further information, such as the location, contact Abbey at 603-315-8137 or Jodie at 424-0629. You can also email them at firstname.lastname@example.org for Abbey or JodieLLL@comcast.com