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The normal reproductive physiological development in the adolescent permits the identification of pathologic conditions that deviate from the predictable sequence of hormonal, anatomic, and histologic changes of puberty. A comprehensive overview of the hypothalamic-pituitary-gonadal axis with the associated hormonal changes of puberty is presented in Chapter 540. The current chapter focuses on the normal anatomic and histologic changes in the major reproductive organs of female and male adolescents during puberty with specific reference to hormonal influences.

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Breast

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Major breast changes occur during 2 stages of reproductive development: puberty and pregnancy. The onset of breast development, or thelarche, heralds both anatomic and histologic changes in the breast. Estrogen is the most influential hormone affecting breast development during puberty. It binds to breast tissue, resulting in stimulation of growth of the glandular ductal system, whereas progesterone is linked to alveolar growth. Other hormones, including insulin, growth hormone, thyroxine, prolactin, and cortisol, and their interactions with estrogen, also play important roles in pubertal breast development. For example, estrogen requires the presence of insulin to stimulate epithelial growth and of growth hormone to affect ductal proliferation.

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Developmental Anatomy and Histology

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There are 4 stages of breast development during the life cycle: prepuberty (atrophic ducts), puberty (lobuloalveolar and ductal growth), lactation (milk secretion), and senescence (regression to atrophic ducts). The first histologic changes at the onset of pubertal breast development consist of proliferation of ductal and stromal tissue and fat deposition resulting in increased volume and the visible breast bud. Lobuloalveolar growth during puberty is influenced by estrogen, progesterone, prolactin, growth hormone, and adrenal steroids. Ductal growth is primarily influenced by estrogen, growth hormone, and adrenal steroids. Maturation to the stage of lactation is mainly stimulated by prolactin and adrenal steroids. The rate of growth and size of the breasts may differ, but major inequities usually disappear with maturity. Abnormalities in development and breast masses are described in Chapter 74.

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Vagina

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The vaginal epithelium is sensitive to hormonal influence. Sequential changes occur throughout the life cycle, including during birth, childhood, puberty, menstrual cycles, pregnancy, and menopause.

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Developmental Anatomy and Histology

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At birth, the vagina is 4 cm long, lengthens approximately 1 cm during early childhood and 8 cm during late childhood, and reaches mature length of 10 to 12 cm by menarche. The vagina at birth resembles the mature vagina with deep cryptic rugae and folds secondary to maternal estrogenic effect. As maternal estrogen levels fall in the infant, the vaginal wall becomes dry, thin, nonelastic, and nonrugated. The vagina remains in this quiescent state until the onset of puberty. During early puberty, increased estrogen levels affect the vaginal epithelia. Such pubertal changes can be noted on examination by identification of the more mature dull pink color of the vaginal mucosa, increased vaginal secretions, and increased vaginal wall flexibility compared with ...

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