Biomedical Engineering Reference
In-Depth Information
Table 5.2
Morphological and functional comparison of normal skin, scar and regenerated skin
(guinea pig dorsum; 1 year)
Normal skin
a
Scar
a
Regenerated skin
a
A. Functional properties of entire skin organ
Thickness of dermis plus epi-
dermis: 1.325 ± 0.275 mm
Scar tissue thickness
< 1.2 mm
Thickness of dermis plus epider-
mis, 1.20 ± 0.325 mm [p(normal)
< 0.6]
d
Moisture permeability:
4.5 ± 0.8 g/cm/h
NA
b
4.7 ± 1.9 g/cm/h [p(normal) < 0.8]
d
Tensile strength: 31 ± 4 MPa
NA
b
14 ± 4 MPa [p(normal) < 0.01]
d
Elongation at break: 90 ± 10 % NA
b
65 ± 10 %
NA
b
Curvature of stress-strain
curve: positive
Positive
Resistance of epidermis to
mild abrasion: high
High
High
Neurological test (pin prick):
positive
NA
b
Positive
B. Epidermis
Epidermal thickness: 40 µm
20-40 µm
30-40 µm (variably hyperplastic)
Keratohyaline granules
Present
Larger and more irregular than in
normal
Keratinocytes joined by
desmosomes
Present
Keratinocytes joined by
desmosomes
Melanocytes with
melanosomes
Reduced numbers of
melanocytes
Melanocytes with melanosomes
Langerhans cells
NA
c
Langerhans cells
C. Basement membrane
Basement membrane, includ-
ing hemidesmosomes, con-
tinuous lamina lucida, lamina
densa and anchoring fibrils
NA
c
Basement membrane, including
hemidesmosomes, continuous
lamina lucida, lamina densa, and
anchoring fibrils
D. Dermis
Complex pattern of rete ridges
and associated dermal papillae
No rete ridge pattern
Complex pattern of rete ridges and
associated dermal papillae (less
complex than normal)
Dermal papillae with subpap-
illary plexus, mostly venules
None
Dermal papillae with subpapillary
plexus, mostly venules
Small, unmyelinated nerve
fibers in subepidermal region
None
Small, unmyelinated nerve fibers
in subepidermal region
Collagen fiber axis orientation
slightly oriented in plane of
epidermis; orientation index,
S = 0.20 ± 0.11
a
Collagen fiber axes
highly oriented in
plane of epidermis; S =
0.75 ± 0.10
a
Moderately oriented in plane
of epidermis; S = 0.48 ± 0.05
a
[p(normal) < 0.001; p(scar)
< 0.001]
d
Collagen fiber diameter in
reticular dermis, 26 ± 13 µm;
fibers loosely packed
11 ± 8 µm; fibers tightly
packed
15 ± 10 µm; fibers loosely packed
[p(normal) < 0.10; p(scar) < 0.50]
d
Stellate-shaped fibroblasts
Elongated fibroblasts
Stellate-shaped fibroblasts
Elastin fibers form fine
network; fibers randomly
oriented in epidermal plane
Elastin fibers thinned,
fragmented; highly
oriented
Elastin fibers delicate, not frag-
mented; slightly oriented
