Breast in the context of "Progesterone"

The nipple is a raised region of tissue on the surface of the breast from which, in lactating females, milk from the mammary gland leaves the body through the lactiferous ducts to nurse 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. The nipple is surrounded by the areola, which is often a darker colour than the surrounding skin.

Male mammals also have nipples but without the same level of function or prominence. A nipple is often called a teat when referring to non-humans. "Nipple" or "teat" can also be used to describe the flexible mouthpiece of a baby bottle.

A man is an adult male human. Before adulthood, a male child or adolescent is referred to as a boy.

Like most other male mammals, a man's genome usually inherits an X chromosome from the mother and a Y chromosome from the father. Sex differentiation of the male fetus is governed by the SRY gene on the Y chromosome. During puberty, hormones which stimulate androgen production result in the development of secondary sexual characteristics that result in even more differences between the sexes. These include greater muscle mass, greater height, the growth of facial hair and a lower body fat composition. Male anatomy is distinguished from female anatomy by the male reproductive system, which includes the testicles, sperm ducts, prostate gland and epididymides, and penis. Secondary sex characteristics include a narrower pelvis and hips, and smaller breasts and nipples.

Puberty is the process of physical changes through which a child's body matures into an adult body capable of sexual reproduction. It is initiated by hormonal signals from the brain to the gonads: the ovaries in a female, the testicles in a male. In response to the signals, the gonads produce hormones that stimulate libido and the growth, function, and transformation of the brain, bones, muscle, blood, skin, hair, breasts, and sex organs. Physical growth—height and weight—accelerates in the first half of puberty and is completed when an adult body has been developed. Before puberty, the external sex organs, known as primary sexual characteristics, are sex characteristics that distinguish males and females. Puberty leads to sexual dimorphism through the development of the secondary sex characteristics, which further distinguish the sexes.

On average, females begin puberty at age 10½ and complete puberty at ages 15–17; males begin at ages 11½–12 and complete puberty at ages 16–17. The major landmark of puberty for females is menarche, the onset of menstruation, which occurs on average around age 12½. For males, first ejaculation, spermarche, occurs on average at age 13. In the 21st century, the average age at which children, especially females, reach specific markers of puberty is lower compared to the 19th century, when it was 15 for females and 17 for males (with age at first periods for females and voice-breaks for males being used as examples). This can be due to any number of factors, including improved nutrition resulting in rapid body growth, increased weight and fat deposition, or exposure to endocrine disruptors such as xenoestrogens, which can at times be due to food consumption or other environmental factors. However, more modern archeological research suggests that the rate of puberty as it occurs now is comparable to other time periods. Growth spurts began at around 10–12, but markers of later stages of puberty such as menarche had delays that correlated with severe environmental conditions such as poverty, poor nutrition, and air pollution. Puberty that starts earlier than usual is known as precocious puberty, and puberty which starts later than usual is known as delayed puberty.

Obstetrics and gynaecology (also spelled as obstetrics and gynecology; abbreviated as Obst and Gynae, O&G, OB-GYN and OB/GYN) is the medical specialty that encompasses the two subspecialties of obstetrics (covering pregnancy, childbirth, and the postpartum period) and gynaecology (covering the health of the female reproductive system – vagina, uterus, ovaries, and breasts). The specialization is an important part of care for women's health.

Postgraduate training programs for both fields are usually combined, preparing the practising obstetrician-gynecologist to be adept both at the care of female reproductive organs' health and at the management of pregnancy, although many doctors go on to develop subspecialty interests in one field or the other.

A mammary gland is an exocrine gland that produces milk in humans and other mammals. Mammals get their name from the Latin word mamma, "breast". The mammary glands are arranged in organs such as the breasts in primates (for example, humans and chimpanzees), the udder in ruminants (for example, cows, goats, sheep, and deer), and the dugs of other animals (for example, dogs and cats) to feed young offspring. 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.

Mammals are divided into 3 groups: monotremes, metatherians, and eutherians. In the case of monotremes, their mammary glands are modified sebaceous glands and without nipples. Concerning most metatherians and eutherians, only females have functional mammary glands, with the exception of some bat species. Their mammary glands can be termed as breasts or udders. In the case of breasts, each mammary gland has its own nipple (e.g., human mammary glands). In the case of udders, pairs of mammary glands comprise a single mass, with more than one nipple (or teat) hanging from it. For instance, cows and buffalo udders have two pairs of mammary glands and four teats, whereas sheep and goat udders have one pair of mammary glands with two teats protruding from the udder. Each mammary gland produces milk for a single teat and is evolutionarily derived from modified sweat glands.

The human areola (areola mammae, /əˈriːələ/ or /ˌæriˈoʊlə/) is the pigmented area on the breast around the nipple. More generally, an areola is a small circular area on the body with a different histology from the surrounding tissue, or other small circular areas such as an inflamed region of skin.

The mature human female nipple has several small openings arranged radially around the tip of the lactiferous ducts, from which milk is released during lactation. The other small openings in the areola are sebaceous glands, also known as areolar glands.

A bra, short for brassiere or brassière (US: /brəˈzɪər/, UK: /ˈbræsɪər, ˈbræz-/), is a type of form-fitting underwear that is primarily used to support and cover a woman's breasts. A typical bra consists of a chest band that wraps around the torso, supporting two breast cups that are held in place by shoulder straps. A bra usually fastens in the back, using a hook and eye fastener, although bras are available in a large range of styles and sizes, including front-fastening and backless designs. Some bras are designed for specific functions, such as nursing bras to facilitate breastfeeding or sports bras to minimize discomfort during exercise.

Although women in ancient Greece and Rome wore garments to support their breasts, the first modern bra is attributed to 19-year-old Mary Phelps Jacob, who created the garment in 1913 by using two handkerchiefs and some ribbon. After patenting her design in 1914, she briefly manufactured bras at a two-woman factory in Boston, before selling her patent to the Warner Brothers Corset Company, which began mass-producing the garment. The bra gained widespread adoption during the first half of the twentieth century, when it largely replaced the corset. The majority of Western women today wear bras, with a minority choosing to go braless. Bra manufacturing and retailing are key components of the multibillion-dollar global lingerie industry.