WHAT A HEALTH PROVIDER sEEs
W
THE PLANNER
|
Tissue Culture and Engineering
S
cientists have long been able to grow cells in glass or plastic
vessels outside the body, using a technology called cell
culture, or tissue culture. Tissue culture requires that cells be
supplied with a balanced salt solution, similar to that found in
the body (that is, tissue culture medium). The tissue culture
j
medium must contain essential nutrients and growth factors
J
as well. Tissue culture has become important for studying
cells and cell processes as well as developing new diagnostic
I
tests. Tissue culture has led to a relatively new technology
'
called tissue engineering.
Tissue engineering allows scientists to grow new tissues in
a laboratory to replace damaged tissues in a body. Tissue engi-
neers have already developed laboratory-grown versions of skin
and cartilage, using the following procedure: Scaffolding beds of
biodegradable synthetic materials or collagen are used as substrates
that permit body cells such as skin cells or cartilage cells to be cultured
As the cells divide and assemble, the scaffolding degrades, leaving the
new, permanent tissue, which is then implanted in the patient.
Other structures that tissue engineers are developing include
bones, tendons, heart valves, bone marrow, and intestines. Work is
also under way to develop insulin-producing cells for patients with dia-
betes, dopamine-producing cells for patients with Parkinson disease,
and even entire livers and kidneys.
1. W hat type of patient would
benefit from tissue-engineered skin?
. If you develop ed an artificial bone, w hat tissues
w ould it contain?
NATIONAL
GEOGRAPHIC
such as the peritoneum, which covers abdominal organs
and lines the abdominal cavity. It also covers the organs
that lie within the cavity. Serous membranes consist
of two parts: a parietal layer and a visceral layer. The
parietal layer (
pa-Rl-e-tal
) is attached to the cavity
wall; the visceral layer (
VIS-er-al
) covers and attaches
to the organs inside these cavities. Each layer consists
of areolar connective tissue covered by a simple squa-
mous
epithelium
called mesothelium
(
mez'-o-THE-
le-um
). Mesothelium secretes serous fluid, a watery
lubricating fluid that allows organs to glide easily over
one another or to slide against the walls of cavities. Se-
rous membranes are associated with the thoracic cavity
(pleura), the heart (pericardium ), and the abdominal
cavity (peritoneum).
Synovial membranes (
si-NO-ve-al
) line the cavi-
ties of some joints. These membranes are composed of
areolar connective tissue and adipose tissue with col-
lagen fibers; they do not have an epithelial layer. Syno-
vial membranes contain cells called synoviocytes, which
secrete synovial fluid. This fluid lubricates the ends of
bones as they move at joints, nourishes the cartilage cov-
ering the bones, and removes microbes and debris from
the joint cavity.
Despite their complexity, many tissues can be created
in the laboratory using either traditional tissue culture
techniques or a relatively new approach called tissue engi-
neering (see
What a Health Provider Sees).
CONCEPT CHECK
1.
What
is the difference between a simple squamous
epithelium and a stratified columnar epithelium?
2.
What
is the function of fibroblasts in connective
tissue?
3.
How
are skeletal, cardiac, and smooth muscle
similar? How do they differ from one another?
4.
What
are the differences between a synovial
membrane and an epithelial membrane?
Cells specialize into Various Tissues 83
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