Chapter 27
The Reproductive System
1057
27
41.
Which structure guides the descent of the testis into the
scrotum?
For answers, see Appendix H.
Puberty
Describe the significant events of puberty and menopause.
FSH and LH levels, elevated at birth, fall to low levels within a
few months and remain low throughout the prepubertal years.
Between the ages of 10 and 15 years, a host of interacting hor-
mones bring on the changes of puberty.
Homeostatic Imbalance
27.11
Failure of the testes to make their normal descent leads to
cryp-
torchidism
(
crypt
5
hidden, concealed;
orchi
5
testicle). Be-
cause cryptorchidism causes sterility and increases the risk of
testicular cancer, surgery is usually performed during early
childhood to rectify this problem.
Check Your Understanding
39.
If a fertilized egg contains X and Y sex chromosomes, a baby
girl will develop, right?
40.
What is the sexually indifferent stage of development?
(c) Female development
Anus
Labia majora
Glans clitoris
Labia
minora
Glans penis
Penis
Scrotum
Anus
(b) Male development
Anus
Labioscrotal
swellings
(labia majora)
Glans clitoris
Urogenital
sinus
Urethral
folds
(labia
minora)
Urethral folds
Glans penis
Labioscrotal
swellings
(scrotum)
Anus
Urethral fold
Labioscrotal
swelling
Urethral groove
Genital
tubercle
Anus
Tail (cut)
(a) Sexually indifferent
stage
Approximately 5 weeks
Figure 27.24
Development of homologous structures of the external genitalia in
both sexes.
The two pictures at the bottom of the figure show the fully developed perineal
region.
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