Mammary glands are made up of a system of ducts surrounded by glandular tissue, which secretes milk. Milk formation is stimulated by the hormones prolactin and growth hormone ; secretion of these hormones is in turn stimulated by the act of suckling. Mammary glands differ somewhat in form from species to species of mammals. Those of monotremes are simple aggregations of glandular tissue along the abdominal wall.
Milk is secreted into depressions and is licked off of the fur by the young. In many species e. In others e. Mammary glands also differ in location and number. Some marsupials have up to 19 or 20 nipples, located in a pouch. Eutherians with large litter sizes have nipples arrayed in lines on each side of the body; in extreme cases, such as the African rat Mastomys, they run from the axillae armpits along the body to the sides of the thighs.
Many mammals have a single pair, but among these the location varies. Manatees, for example, have a pair of axillary nipples; in humans, the nipples are pectoral; in horses, abdominal. The basic components of the mammary gland are the alveoli hollow cavities, a few millimetres large lined with milk-secreting cuboidal cells and surrounded by myoepithelial cells.
These alveoli join up to form groups known as lobules, and each lobule has a lactiferous duct that drains into openings in the nipple. The myoepithelial cells can contract, similar to muscle cells, and thereby push the milk from the alveoli through the lactiferous ducts toward the nipple, where it collects in widenings sinuses of the ducts. As the infant begins to suckle, the hormonally mediated "let down reflex" ensues and the mother's milk is secreted into - not sucked from the gland by - the baby's mouth.
Reference Terms. Related Stories. According to a new study, dental epithelial stem cells from mice can generate mammary ducts and This new amyloid protein is known to be the lipopolysaccharide binding protein LBP and accumulated very Oxytocin causes milk to eject from the glands. With the decrease in the production of estrogen around menopause , mammary glands shrink, causing breasts to appear softer and less full with age.
Female breast cancer is one of the most common cancers, affecting 1 in 8 women. Hormone therapy may alter the risk of breast cancer Breast cancer in cisgender men and transfeminine people not on hormone therapy is much rarer but does occur.
Transmasculine people who were on puberty blockers will have a level of breast cancer risk similar to cisgender men and transfeminine people not on gender-affirming hormone therapy. Breast cancer can start from multiple locations in the breast, including the mammary glands, milk ducts, and other tissues.
Left undetected, breast cancer can spread to other organs through the blood and lymph node system. Mammary duct ectasia most commonly occurs near or after menopause. Ectasia is a noncancerous thickening of the milk ducts.
It does not always cause symptoms, but sometimes can present as breast pain and swelling, nipple discharge, or a nipple that pulls inward.
Ectasia does not always require treatment, but sometimes antibiotics or surgical removal of the duct may be required. Fluid-filled cysts in the breasts are usually benign. Breast cysts develop in milk ducts and are fairly common in later childbearing years.
About 1 in 4 breast lumps are cysts. It is unknown what causes cysts, but they may develop as a result of hormonal fluctuations. In addition to tumors and cysts, lumps in the breast can indicate fibrocystic breast changes. Fibrocystic breast change is a common, benign condition that affects people primarily before menopause.
It is characterized by lumpy breast tissue. Mastitis is an infection that occurs in the breast tissue. It most commonly affects women who are breastfeeding. Mastitis is caused by bacteria that enter the breast through a milk duct or a crack in the skin. Mastitis symptoms include breast swelling, tenderness, redness, fever, and flu-like muscle aches. At-home treatment usually resolves mastitis, but some cases may require antibiotics.
Breast pain can happen as a result of a number of things, including cysts, hormonal fluctuations, pregnancy, infection, breastfeeding, and sometimes cancer. Depending on the cause, breast pain can often be managed at home. It is important, however, to have persistent or severe pain and all lumps evaluated by a healthcare provider. Clinical breast exams and self-exams used to be considered a gold standard for early detection of breast cancer.
Even without monthly self-breast exams, most people are familiar with their breasts and often notice changes or lumps through normal activities like showering or changing clothes. In such a case, a clinical breast exam is often performed. Mammograms are X-rays of the breast. During a mammogram, you will stand in front of a specialized X-ray machine.
A technician will place your breast on a plate, then bring another plate down to flatten the breast. Finally, the technician will take a picture of your breast. This will be repeated from the top and the side on both breasts.
A mammogram may be recommended to identify a lump that you or your healthcare provider have detected in your breast. They are also used as a screening tool to detect breast cancer. The American College of Obstetriciansand Gynecologists recommends that women at average risk of breast cancer get a mammogram every one to two years beginning at age 40, and no later than 50; screening should continue until at least age 75 years.
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