Areolae become more pigmented and erectile, and Montgomery glands at the periphery of the areola appear more prominent as development progresses. Breast development ( Fig. 3.1A) occurs due to ovarian estrogen secretion, although other hormones are involved. The first evidence of pubic hair is quite subtle and often requires careful inspection. Some girls first demonstrate pubic hair appearance before breast development. Styne MD, in Pubertal Suppression in Transgender Youth, 2019 Female Changesīreast development is the first sign of puberty noted by most examiners but an increase in height velocity is closely temporaly associated. Menarche usually occurs ~2 yr after initiation of breast development.ĭennis M. Lack of development by age 13 yr is considered delayed and warrants endocrinology evaluation. Maturation can sometimes occur asymmetrically owing to fluctuation of the hormonal environments and various end-organ sensitivities. Once thelarche is initiated, normal development of the breast occurs over 2-4 yr and is classified by the sexual maturity rating system (also known as Tanner staging) into five stages (see Chapter 132). These hormones then stimulate the ovaries to produce estradiol, which leads to breast development. This occurs when the hypothalamus releases gonadotropin-releasing hormone, which stimulates the pituitary gland to produce follicle-stimulating hormone and luteinizing hormone. The initiation of thelarche and progression in females is affected by race, with normal thelarche occurring earlier in African American girls than in white or Asian girls. Thelarche, or the onset of pubertal breast development, is hormonally mediated and normally occurs between the ages of 8 and 13 yr.
It is initially depressed or inverted, and later becomes elevated. The areola appears at 5 mo of gestation, and the nipple is seen shortly after birth. This breast bud regresses within the first month of life once estrogen stimulation is no longer present. The breast bud, under the stimulation of maternal estrogen, becomes palpable at wk 34 of gestation. The initial lactiferous ducts form between wk 10 and 20 and become interspersed through the developing mesenchyme, which becomes the fibrous and fatty portions of the breast. The ridge above and below the area of the pectoralis muscle recedes in utero, leaving the mammary primordium, which is the origin of the lactiferous ducts. They extend from the area of the developing axilla to the area of the developing inguinal canal. Kliegman MD, in Nelson Textbook of Pediatrics, 2020 Breast Developmentĭevelopment of the breast begins around wk 5 of gestation, when the ectoderm on the anterior body wall thickens into two ridges known as the mammary ridges.