Prenatally, organisms have the bipotentiality to differentiate along either male or female lines, a
process with different stages, each with a narrow window of time, during which testosterone plays a pivotal
role in the case of male sexual differentiation. During puberty, the body directs the masculinization process
with growth of the genitalia and prostate. Body contours become male, with an average height of 10-15
centimeters greater than that of females, a greater bone and muscle mass, a male hair pattern and a male-type
fat distribution. These pubertal developments, largely reversible in case of severe androgen deficiency, require
adult levels of testosterone throughout life. A new area of interest is in exploring how far age-related body
changes (loss of bone and muscle mass, a shift into a higher ratio of body fat/lean body mass) are part of an
age-related decline of testicular testosterone production. Therefore, throughout life, testosterone is essential
for a normal male life.

Keywords: Aging, Bone, Penis, Sex differentiation, Skin