Breast development happens in certain stages during a woman's life: first before birth, again at puberty, and later during the childbearing years. This starts with a thickening in the chest area called the mammary ridge or milk line. By the time a baby girl is born, nipples and the beginnings of the milk-duct system have formed. The first thing to develop are lobes, or small subdivisions of breast tissue. Mammary glands develop next and consist of 15 to 24 lobes. Mammary glands are influenced by hormones activated in puberty.
Mammary gland , milk-producing gland characteristic of all female mammals and present in a rudimentary and generally nonfunctional form in males. Mammary glands are regulated by the endocrine system and become functional in response to the hormonal changes associated with parturition. In the primitive monotreme mammals e. Unique in monotremes, the mammae lack nipples and are functional in both sexes.
Mammalia are so named based on the presence of the mammary gland in the breast. The mammary gland is an epidermal appendage, derived from the apocrine glands. The human breast consists of the parenchyma and stroma, originating from ectodermal and mesodermal elements, respectively. Development of the human breast is distinctive for several reasons. The human breast houses the mammary gland that produces and delivers milk through development of an extensive tree-like network of branched ducts.
Milk is synthesized by mammary epithelial cells of lactating mammals. The synthetic capacity of the mammary gland depends largely on the number and efficiency of functional mammary epithelial cells. Structural development of the mammary gland occurs during fetal growth, prepubertal and post-pubertal periods, pregnancy, and lactation under the control of various hormones particularly estrogen, growth hormone, insulin-like growth factor-I, progesterone, placental lactogen, and prolactin in a species- and stage-dependent manner. Milk is essential for the growth, development, and health of neonates. Amino acids AA , present in both free and peptide-bound forms, are the most abundant organic nutrients in the milk of farm animals.