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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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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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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 ...