Dense irregular connective tis-
sue, thin skin.
dense irregular connective tissue
dermis of thin skin. The epidermis is composed of
; the dermis is composed of dense
irregular connective tissue and lies beneath the
epidermis. “Dense” refers to the high abundance
of collagen F
bers (but fewer cells) compared to
loose connective tissue. “Irregular” indicates that
the orientation of the F
ber bundles is in many dif-
ferent directions (or randomly oriented bundles).
This type of connective tissue contains mostly
lagen f bers
with a lesser number of other F
such as elastic F
bers. The skin has a thick layer
of dense irregular connective tissue, with F
arranged in various directions to resist stretching
forces in any direction. Dense irregular connective
tissue is prominent in the dermis of the skin, mam-
mary glands, and capsules of many organs.
Hypertrophic Scars and Keloids.
are disorders caused by
in the skin by
. They often
occur after burns, radiation injury, or surgical procedures.
appear raised, are characterized by red-
ness, and usually remain within the margins of the original
wound. There is a tendency for spontaneous regression
over time. If the scar tissue grows beyond the boundaries
of the original wound and does not regress, it is called a
. A keloid is more severe and more difF
cult to treat
than a hypertrophic scar. Treatments of hypertrophic scars
and keloids include cryosurgery (freezing), laser surgery,
and steroid injections. This photomicrograph is a keloid
on the earlobe; the collagen F
bers appear thicker and
. The number of
A representation o± dense irreg-
ular connective tissue.
The background represents
Collagen f bers
are represented by randomly
arranged, thick, pink bundles, and
elastic f bers
indicated by thinner dark lines. A few
are scattered sparsely among these F bers. Most col-
lagen and elastic F bers are produced by F broblasts.
Maintaining the normal metabolism of collagen is
very important to the body.
Malfunctioning collagen can cause a series of con-
nective tissue diseases such as
(see Table 4-1). Overproduction of collagen
in the dermis of the skin can cause