Changes in hypothalamic-pituitary-gonadal endocrine function
lead to the striking changes associated with secondary sexual development.
Endocrine changes of puberty are divided into (1) gonadarche, or
the awakening of gonadal action during which increased pituitary gonadotropins
cause the secretion of gonadal steroids, and (2) adrenarche, or
the awakening of adrenal androgen secretion caused by still undefined
Stages of pubertal development are described using a sexual
maturity rating scale popularized by Tanner. Staging provides
an objective, consistent description of physical development (Fig. 540-1). Breast development (caused by ovarian
estrogens) and pubic hair development (caused by adrenal androgens)
are usually, but not always, coordinated in girls (eg, premature
adrenarche or premature thelarche) so that each should be documented.
Similarly, in boys, testicular/penile development and pubic
hair development may not be synchronous because the adrenal gland
can produce its own androgens out of sequence with testicular androgen
secretion, due to either adrenal disease or adrenarche.
A: Genital development and pubic hair growth among boys.
Stage G1 (upper left), prepubertal. Stage G2 (upper
right), enlargement of testis to more than 2.5 cm, appearance
of scrotal reddening, and increase in rugations. Stage G3, increase
in length or 4 cm volume and to a lesser extent breadth of penis
with further growth of testis. Stage G4, further increase in size
of penis and testes and darkening of scrotal skin. Stages G5 and
G6 (lower panels), adult genitalia. Stage P1 (upper
panels), preadolescent, no pubic hair. Stage P2 (middle
left), sparse growth of slightly pigmented, slightly curved
pubic hair mainly at the base of the penis. Stage P3 (middle
right), thicker curlier hair spread laterally. Stage P4
(lower left), adult-type hair that does not yet
spread to medial thighs. Stage P5 (lower right),
adult-type hair spread to medial thighs. B: Appearance of pubic
and labial hair among girls. Stage PH1 (upper left),
prepubertal, no pubic hair. Stage PH2 (upper right, middle
left), sparse growth of long, straight, or slightly curly
minimally pigmented hair, mainly on labia. Stage PH3 (middle
right), considerably darker and coarser hair spreading
over mons pubis. Stage PH4 (lower left), thick
adult-type hair that does not yet spread to the medial surface of
the thighs. Stage PH5 (lower right), hair is adult
type and is distributed in the classic inverse triangle. C: Breast
development. Stage B1 (upper panels), prepubertal,
elevation of the papilla only. Stage B2, breast buds visible or
palpable with enlargement of the areola. Stage B3, further enlargement
of the breast and areola with no separation of their contours (not
shown). Stage B4, projection of areola and papilla to form a secondary
mound over the rest of the breast. Stage B5 (lower panel),
mature breast with ...
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