Biomedical Engineering Reference
In-Depth Information
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Fig. 4.8
Quantitative distinction between scar and physiologic dermis using laser light scatter-
ing from histological tissue sections.
To p
: The laser beam passes through the histologic section,
shown above as a tissue slice cut perpendicular to the long axis of the scar in the guinea pig
defect. The major direction of deformation due to wound contraction (
broken lines
) is perpendic-
ular to the long axis of scar. The resulting scattering pattern is viewed on the photographic plane;
it is characterized by the scattering angle
θ
and the azimuthal (
rotation
) angle
β
. The orientation
index of tissue sections, cut either parallel or perpendicular to the major direction of contraction,
is reported in Table
4.1
.
Bottom
: Four areas of the tissue section were sampled by the light beam
(sampled area shown as circles in photograph of histologic section,
top
). The resulting scattering
patterns are shown below the photograph of the histologic tissue section; they contain informa-
tion on the average orientation and diameter of collagen fibers in each of the areas. Patterns
from physiologic dermis (extreme
left
and extreme
right
) deviate from being perfectly circular,
indicative of a small amount of fiber orientation in the plane of the epidermis. Patterns from scar
tissue (inside
left
and inside
right
) show strong fiber orientation in the plane. (From Ferdman and
Yannas 1993)
