| Mammary crest | |
|---|---|
 Natural milk lines in the human body | |
| Details | |
| Identifiers | |
| Latin | crista mammaria |
| Anatomical terminology | |
The mammary ridge or mammary crest is a primordium [1] specific for the development of mammary glands.
| Mammary crest | |
|---|---|
| Natural milk lines in the human body | |
| Details | |
| Identifiers | |
| Latin | crista mammaria |
| Anatomical terminology | |
The mammary ridge or mammary crest is a primordium [1] specific for the development of mammary glands.
The mammary ridge is primordial for the mammary glands on the chest in humans, and is associated with mammary gland and breast development.
In human embryogenesis, the mammary ridge usually appears as a narrow, microscopic ectodermal thickening during the first seven weeks of pregnancy and grows caudally as a narrow, linear ridge. [1] In many mammals, these glands first appear as elevated ridges along the milk lines, which then separate into individual buds located in regions lateral to the ventral midline. The location of these buds varies according to species: they are located in the thoracic region in primates, in the inguinal area in ungulates, and along the entire length of the trunk in rodents and pigs. [2]
A mammary ridge, or crest, usually stops growing at eight weeks and its length is regressed starting at the caudal end and extending cranially, [1] so that what remains is a round, ectodermic placode where the axilla develops. When shortening of the mammary crest is complete, the structure remains prominent in the areas where the mammary glands eventually form. The mammary lines begin to shorten and ectodermal cells begin to divide and grow into the mesenchymal cell layer. [3] A basement membrane separating the expanding ectodermal crest structure and the underlying mesoderm usually remains. The mammary ridge then becomes recognizable in the thoracic region in the human embryo. Nipples develop on the milk lines of therian mammals.
In humans, milk lines form as thickenings of the epidermis of the mammary ridge, along the front surface of both sexes. Milk lines appear in the seventh week of embryonic development before human sexual differentiation, which explains why male humans have nipples. After initial development of the milk lines they go into remission. Most humans have two nipples, but in some cases more than two will develop. These additional nipples usually grow along the milk line.
A recently published study demonstrates that focal fat pads on the front of human torsos are of mammary ridge origin. Eight pairs of fatty mounds were consistently found running along a curved line from the armpits to the groins in nearly all lean women and men, consistent with the location of the embryological mammary ridge line. This finding explains why fat on the front of the body is less responsive to diet and exercise than fat elsewhere in most people—because it is actually of breast origin and therefore sensitive more to hormonal influence than caloric intake or burn. [4]
The breast is one of two prominences located on the upper ventral region of the torso among humans and other primates. Both sexes develop breasts from the same embryological tissues. The relative size and development of the breasts is a major secondary sex distinction between males and females.
The endocrine system is a messenger system in an organism comprising feedback loops of hormones that are released by internal glands directly into the circulatory system and that target and regulate distant organs. In vertebrates, the hypothalamus is the neural control center for all endocrine systems.
The nipple is a raised region of tissue on the surface of the breast from which, in females, milk leaves the breast through the lactiferous ducts to breastfeed an infant. The milk can flow through the nipple passively or it can be ejected by smooth muscle contractions that occur along with the ductal system. Male mammals also have nipples but without the same level of function, and often surrounded by body hair.
A mammary gland is an exocrine gland in humans and other mammals that produces milk to feed young offspring. Mammals get their name from the Latin word mamma, "breast". The mammary glands are arranged in organs such as the breasts in primates, the udder in ruminants, and the dugs of other animals. Lactorrhea, the occasional production of milk by the glands, can occur in any mammal, but in most mammals, lactation, the production of enough milk for nursing, occurs only in phenotypic females who have gestated in recent months or years. It is directed by hormonal guidance from sex steroids. In a few mammalian species, male lactation can occur. With humans, male lactation can occur only under specific circumstances.
Reduction mammoplasty is the plastic surgery procedure for reducing the size of large breasts. In a breast reduction surgery for re-establishing a functional bust that is proportionate to the patient's body, the critical corrective consideration is the tissue viability of the nipple–areola complex (NAC), to ensure the functional sensitivity and lactational capability of the breasts. The indications for breast reduction surgery are three-fold – physical, aesthetic, and psychological – the restoration of the bust, of the patient's self-image, and of the patient's mental health.
Areolar glands, also known as glandulae areolares, Montgomery glands, and tubercula areolae, are 10-15 elevations found on the areola. They are usually arranged in a circle around the nipple, and can be particularly visible when the nipple is erect. Their role is to promote adequate breastfeeding of the infant.
A supernumerary nipple is an additional instance of nipple occurring in mammals, including humans and monkeys. They are often mistaken for moles. Studies variously report the prevalence of supernumerary nipples as approximately 1 in 18 and 1 in 40.
Witch's milk or neonatal milk is milk secreted from the breasts of some newborn human infants of either sex. Production of neonatal milk by infants usually resolves itself and does not require treatment unless it is caused by an underlying condition or medications. It is thought to be caused by the exposure to an elevated level of estrogen to infants during pregnancy or decreased exposure of estrogen to infants after birth. Its production also may be caused by certain medications. The composition of neonatal milk is similar to maternal milk for most of their components except for fats and one type of antibody.
Lactiferous ducts are ducts that converge and form a branched system connecting the nipple to the lobules of the mammary gland. When lactogenesis occurs, under the influence of hormones, the milk is moved to the nipple by the action of smooth muscle contractions along the ductal system to the tip of the nipple. They are also referred to as galactophores, galactophorous ducts, mammary ducts, mamillary ducts or milk ducts.
Human placental lactogen (hPL), also called human chorionic somatomammotropin (hCS) or human chorionic somatotropin, is a polypeptide placental hormone, the human form of placental lactogen. Its structure and function are similar to those of human growth hormone. It modifies the metabolic state of the mother during pregnancy to facilitate energy supply to the fetus. hPL has anti-insulin properties. hPL is a hormone secreted by the syncytiotrophoblast during pregnancy. Like human growth hormone, hPL is encoded by genes on chromosome 17q22-24. It was identified in 1963.
Mastopexy is the plastic surgery mammoplasty procedure for raising sagging breasts upon the chest of the woman, by changing and modifying the size, contour, and elevation of the breasts. In a breast-lift surgery to re-establish an aesthetically proportionate bust for the woman, the critical corrective consideration is the tissue viability of the nipple-areola complex (NAC), to ensure the functional sensitivity of the breasts for lactation and breast-feeding.
Ectrodactyly–ectodermal dysplasia–cleft syndrome, or EEC, and also referred to as EEC syndrome and split hand–split foot–ectodermal dysplasia–cleft syndrome is a rare form of ectodermal dysplasia, an autosomal dominant disorder inherited as a genetic trait. EEC is characterized by the triad of ectrodactyly, ectodermal dysplasia, and facial clefts. Other features noted in association with EEC include vesicoureteral reflux, recurrent urinary tract infections, obstruction of the nasolacrimal duct, decreased pigmentation of the hair and skin, missing or abnormal teeth, enamel hypoplasia, absent punctae in the lower eyelids, photophobia, occasional cognitive impairment and kidney anomalies, and conductive hearing loss.
Amastia refers to a rare clinical anomaly in which both internal breast tissue and the visible nipple are absent on one or both sides. It affects both men and women. Amastia can be either isolated or comorbid with other syndromes, such as ectodermal dysplasia, Syndactyly and lipoatrophic diabetes. This abnormality can be classified into various types, and each could result from different pathologies. Amastia differs from amazia and athelia. Amazia is the absence of one or both mammary glands but the nipples remain present, and athelia is the absence of one or both nipples, but the mammary gland remains.
Ptosis or sagging of the female breast is a natural consequence of aging. The rate at which a woman's breasts drop and the degree of ptosis depends on many factors. The key factors influencing breast ptosis over a woman's lifetime are cigarette smoking, her number of pregnancies, higher body mass index, larger bra cup size, and significant weight change. Post-menopausal women or people with collagen deficiencies may experience increased ptosis due to a loss of skin elasticity. Many women and medical professionals mistakenly believe that breastfeeding increases sagging. It is also commonly believed that the breast itself offers insufficient support and that wearing a bra prevents sagging, which has not been found to be true.
A fat pad is a mass of closely packed fat cells surrounded by fibrous tissue septa. They may be extensively supplied with capillaries and nerve endings.
Lactation describes the secretion of milk from the mammary glands and the period of time that a mother lactates to feed her young. The process naturally occurs with all sexually mature female mammals, although it may predate mammals. The process of feeding milk in all female creatures is called nursing, and in humans it is also called breastfeeding. Newborn infants often produce some milk from their own breast tissue, known colloquially as witch's milk.
Breast development, also known as mammogenesis, is a complex biological process in primates that takes place throughout a female's life.
Supernumerary nipples–uropathies–Becker's nevus syndrome is a skin condition that may be associated with genitourinary tract abnormalities. Supernumerary nipples, also referred to as polythelia or accessory nipples, is a pigmented lesion of the skin that is present at birth. This pigmentation usually occurs along the milk lines, which are the precursors to breast and nipple development. Clinically, this congenital condition is generally considered benign, but some studies have suggested there may be an association with kidney diseases and cancers of the urogenital system.
A mammary alveolus is a small cavity or sac found in the mammary gland. Mammary alveoli are the site of milk production and storage in the mammary gland. Mammary alveoli cluster into groups called mammary lobules, and each breast may contain 15 to 20 of these lobules. The lobules drain milk through the lactiferous ducts out of the nipples.
Establishment of breastfeeding refers to the initiation of providing breast milk of mother to baby. According to the World Health Organization(WHO), breastfeeding is the best way to provide nourishment, including essential nutrients, energy and antibodies, to infants and toddlers. The start of breastfeeding is supported by the milk production which depends on the development of internal and external breast structure and hormonal control on milk secretion. Besides milk supply, adopting the correct approach of breastfeeding helps build up the maternal bond, which in turn promotes breastfeeding. Not only does nursing strengthen the mother-child relationship, but it also improves the intelligence and immunity of breastfed children and diminishes breastfeeding mothers' risks to have ovarian and breast cancer.