Breast is a unique mammalian organ of human beings and mammals. In humans, it is located in the fourth intercostal space of the clavicle midline, one on the left and one on the right. Normal children and men are not obvious. The growth of women in adolescence is due to the stimulation of sex hormones. The breasts of adult women are hemispherical, the nipples are cylindrical, the skin in the central part is reddish, and the sebaceous glands are called areola.
The breast is mainly composed of 15~20 glands (mammary glands), lobules and adipose tissue. Glands are arranged radially, and their mammary ducts face the areola and open to the nipple. During pregnancy and lactation, the glands are the most developed, the breasts are enlarged, protruding forward or drooping; The areola is enlarged, the color is deepened, and vein dilatation can be seen on the surface of breast skin. After menopause, the ovary stops moving, and the volume and fat of the breast are degraded and replaced by fibrous tissue.
Extended data:
Breast development:
Affected by regional and ethnic factors, women's breasts begin to develop at different times. Most female breasts begin to develop at the age of 8- 13, and fully mature at the age of 14- 18. Breast development mostly starts from the left side, and it takes about 3-5 years from the beginning to full maturity.
The first stage (1~9 years old): before puberty, the breast has not yet developed.
The second stage (10~ 1 1 year): at the early stage of breast development, the breast germ under the nipple began to grow and showed an obvious dome-shaped bulge.
The third stage (12~ 13 years old): the breasts are round and adult-shaped, but they are still small.
The fourth stage (14~ 15 years old): the breast grows rapidly, and the nipple and areola protrude forward like a ball.
The fifth stage (16~ 18 years old): normal adult breasts are formed, and the globules of nipple and areola are integrated with the circle of breast.
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