Expert Analysis: A girl with normal development has menstruation from the age of 13-18 until her reproductive organs mature, and this physiological period is called puberty. During this period, in addition to menstruation, the girl’s breasts, which are her secondary sex characteristics, are clearly developed. Inside the breast there are alveoli and ducts, the alveolar cells that function as lactation and the ducts that are the pathways for milk. These two structures are stimulated by the female hormones (also called hormones) secreted by a woman’s ovaries. Adolescent girls rarely lactate. The breast does not produce milk during development. The reason for this is the source of lactogen, which is produced by an endocrine gland in the human brain called the pituitary gland (about a gram in size, resembling a fava bean), but it is also controlled by the inhibitory factor of lactogen secreted by the hypothalamus, which limits the secretion of lactogen by the pituitary gland, so lactation is a special function of maternal child-rearing. Lactation does not occur in women in general, and in adolescent girls in particular. Lactation is an abnormality. There are two reasons for this abnormality: first, a lactogenic glandular tumor has occurred in the pituitary gland; second, although no lactogenic tumor has occurred, the cells of the pituitary gland are stimulated by the prolactin-promoting factor secreted by the hypothalamus, resulting in excessive secretion of lactogen, called hyperprolactinemia. The diagnosis can be further confirmed by cranial CT or MRI and measurement of serum prolactin level. If there is a tumor, it can be treated with gamma knife and cured without craniotomy: if it is not a tumor, but only hyperprolactinemia, it can be treated with symptomatic medication, but it must be taken under the guidance of a doctor. Learn to self-examine the breast Before the ovaries secrete luteinizing hormone, the glandular lobules have extremely limited development. After sexual maturity, especially during pregnancy, the glandular lobules can develop fully under the combined and repeated action of progesterone and estrogen. Otherwise, the epithelial cells of the terminal milk ducts are prone to abnormalities, such as cystic hyperplasia.