1.Embryonic stage
The development of the human mammary gland begins at the end of the first embryonic month, and by the 6th week of embryonic development, the mammary gland line appears on the ectoderm, referred to as the mammary line, and by the 2nd month, there can be multiple epithelial thickening on the mammary base line, forming the mammary crest, which can develop into multiple mammary gland primordia. During the third month of embryonic development, the adjacent part of the milk bud forms the lobular bud, which is the primitive structure of the mammary alveolus, and the distal part of the milk bud develops into the milk duct, and its distal end develops into the nipple. After the birth of the fetus, the connective tissue below the nipple proliferates, making the mammary area prominent and constituting the nipple, and the pair of breasts has basically formed from the external view of the chest. If all of the breast line degenerates during the embryonic period or all of one side degenerates, it is manifested as congenital absence of the breast or unilateral absence of the breast.
2.Infancy and early childhood
When an infant is born, the nipple is sunken and the areola is formed and contains a 15-20 lobe ductal alveolar system with a small amount of colostrum in the alveoli, which is discharged from the nipple within a week after birth and can last until three or four weeks after delivery, during which the alveolar tissue also rapidly degenerates into ductal tissue. During early childhood and childhood, the mammary glands remain relatively stable and quiescent until the onset of puberty.
3.Adolescence
From the age of 9-10, the nucleus of the breast appears and gradually increases in size due to the stimulation of hormones secreted by the ovaries, and basically takes shape by the age of 15. After puberty, the secretion of gonadotropins from the hypothalamus and pituitary gland increases, stimulating the follicles to develop further and producing hormones. Under the action of a series of hormones, the ducts and follicles of the breast develop, the breasts gradually become fuller, and the nipples and areolas increase in size one after another. A recent study by the University of Washington shows that more exercise for girls from the developmental stage (age 12) can effectively prevent breast cancer in adulthood. If women move more during adolescence and into adulthood, their chances of developing breast cancer during menopause are 23% lower than those of sedentary women who are not physically active. In addition, between the ages of 12 and 22, the best time for women to exercise, experts recommend that women take a variety of ways to exercise, such as running and walking.
4.Adulthood
Adult women’s breasts change accordingly with the hormonal changes at different stages of the menstrual cycle. 7-10 days before menstruation, the level of estrogen gradually increases, the breast gland appears proliferation-like changes, manifested as breast epithelial hyperplasia, tissue congestion, etc.. After ovulation, the level of progesterone rises, the ductal epithelial cells in the lobules become enlarged and the ductal secretions increase. Therefore, before menstruation, some women may feel that their breasts are swollen, tense and firm, and even have varying degrees of pain and tenderness. After menstruation, the estrogen and progesterone levels decrease rapidly, the stimulation of estrogen on the mammary glands is weakened, the breast cells atrophy, congestion subsides, and the volume of the lobules and alveoli of the breast shrinks. At this point, the breasts become smaller and softer, and the pain and tenderness disappear. A few days later, with the start of the next menstrual cycle, the breast enters another proliferative phase of change. The numerous repetitions of the menstrual cycle keep the breast in this cyclical change of proliferation and rejuvenation, re-proliferation and rejuvenation. Estrogen and other hormones are not only related to some physiological changes in the breast, but also to some pathological changes in the breast. Higher levels of estrogen in the body during this period can also cause diseases such as breast fibroadenoma, so attention should be paid to timely detection and treatment.
Adult women should develop good dietary habits, increase the intake of animal protein, and perform more exercises such as chest lifting and chest expansion to exercise the pectoral muscles to make them developed and fat, so as to keep the breasts upright and healthy. In addition, the week before menstruation as far as possible to light and high fiber food, avoid spicy food stimulation, aggravating the period of breast pain. Research studies have shown that unmarried women of advanced age and advanced first birth are high risk factors for breast cancer. In this group, it is difficult to maintain normal estrogen levels in their bodies, which increases the risk of developing breast cancer. Therefore, it is recommended that women of childbearing age should marry at an appropriate age and insist on breastfeeding.
5.Pregnancy period
During pregnancy, under the joint action of hormones secreted by ovaries and placenta, breast lobules are highly proliferated and glandular follicles are formed, nipples and areolas are enlarged, coloring is deepened, and areola glands secrete vigorously, which makes breasts fully developed and ready for breastfeeding. During pregnancy, the breasts are fuller and too tight or too small bras will prevent the full development of the breasts. Wearing the right bras to support and protect the enlarged breasts can prevent the breasts from sagging in the future; the nipples should be kept clean during pregnancy. In addition, prenatal checkups should pay special attention to mammography to ensure normal lactation after delivery.
6.Lactation period
Two to three days after delivery, under the action of prolactin secreted by the pituitary gland, each lobe of the breast begins to secrete milk alternately. Lactation is the most special and important period in a woman’s breast life, it is vital to do a good job of breast care during lactation.
(1) Pay attention to nipple care. Daily care of the nipples during breastfeeding is very important. Wash the nipples and areola with warm water before and after each breastfeeding session to keep them clean and dry. If the nipple is broken, use a breast pump to suck out the milk into a bottle for feeding so that the broken nipple can easily heal.
(2) Develop good breastfeeding habits. The number of times and time of breastfeeding should be arranged regularly, with each feeding lasting l0 to 15 minutes, and the milk that cannot be sucked should be sucked up to prevent breast lumps caused by milk retention, thus preventing the occurrence of mastitis, and breast emptying is also conducive to promoting milk secretion. Breastfeeding should be rotated between both breasts to prevent asymmetry of the breasts.
(3) Wear a suitable bra. During breastfeeding, the breasts are thick and full, and the weight of the breasts themselves suddenly increases. A suitable bra can hold up the breasts, reduce the excessive stretching of the breast ligaments, and prevent the breasts from sagging; the nipples often overflow with milk during breastfeeding, so you should choose a loose, soft and absorbent bra to avoid damage caused by friction between the nipples and hard objects.
(4) Actively prevent mastitis. During breastfeeding, improper breast care can easily cause milk stagnation and induce acute mastitis. Before each breastfeeding, massage or hot compress the breasts to help unblock the draining pathway.
7, menopause
During menopause, due to the decline in hormone levels in the body, the lobules and ducts of the breast gradually shrink, while on the contrary, the fatty tissue in the breast increases, and the surrounding fibrous tissue increases and is denser. Due to the deposition of fat and the sagging of the skin on the breast surface, the breasts gradually sag, a phenomenon that becomes more pronounced with age. After middle age, the incidence of breast diseases, especially breast cancer, increases, therefore, women in this period should pay special attention to breast examination and health care. Therefore, women in this period should pay special attention to breast examination and health care. They should insist on monthly breast self-examination and annual medical checkup at a professional hospital to pay attention to small changes in the breast and to detect and treat problems in time. Those who have high risk factors for breast cancer should have regular breast examinations earlier to be more vigilant and achieve early detection, early diagnosis and early treatment, which is crucial to improve the prognosis. Modern women are under high mental stress and these factors can lead to endocrine disorders and promote the occurrence of breast diseases. Therefore, middle-aged women should pay attention to the combination of work and rest, regulate their emotions, keep their spirits relaxed and happy, avoid excessive depression, anger and emotional excitement, good mental state has a positive effect on the prevention of breast disease. In addition, a high-fat diet may promote the synthesis of estrogen in the body and indirectly increase the level of estrogen in the body, so you should avoid high-fat food intake, reasonable weight control, to prevent obesity, thereby reducing the occurrence of breast disease.
8.After menopause
After menopause, the level of estrogen and progesterone in the body will rapidly decline, accelerating the degeneration of the breast gland, this change first occurs in the lobules and alveoli of the breast, histologically manifested as follows: the lobules of the breast are incomplete, shrinking, the number decreases, followed by the atrophy of small ducts, epithelial cells reduce to disappear, the lumen is narrowed, interstitial fibrosis, collagenization, adipose tissue will be filled in large quantities, the nodular sense of the breast is less and less obvious. Women in this stage should pay attention to sudden abnormal sensations, changes in breast volume and shape, and nipple overflow, in addition to monthly breast self-examinations and specialist breast examinations every 1-2 years, and seek timely treatment. It is important to note that women should be cautious about taking hormone replacement agents after menopause, and if they do, they should do so under the guidance of a doctor. In addition, some women use exogenous estrogen for a long time to maintain a plump body and a pretty face, which artificially prolongs the stimulation of estrogen on breast epithelial cells and changes the secretion environment in the body, leading to cell malignancy and inducing breast cancer. Therefore, the abuse of exogenous estrogens should be avoided. In addition, with the improvement of living standard, people’s diet structure and lifestyle have changed, and the high-fat and high-sugar diet and sedentary lifestyle habits increase the risk of breast cancer. Therefore, it is advisable to consume more fresh vegetables and fruits, reduce the intake of high-fat, high-sugar, alcoholic, coffee-based beverages and estrogen-containing health products, exercise in moderation and maintain an ideal body weight, which are also crucial for breast cancer prevention. These, again, apply to women of all ages.