A structural model used to evaluate the changing microstructure of maturing rat skin

Area of Science:

• Biomechanics
• Materials Science
• Dermatology

Background:

• Soft biological tissues, like skin, exhibit complex non-linear mechanical responses.
• The collagenous network is a primary determinant of skin's mechanical properties.
• Understanding skin's microstructure is crucial for diagnosing and treating conditions affecting its mechanical integrity.

Purpose of the Study:

• To adapt and validate a microstructurally based model for analyzing the non-linear mechanical response of rat skin's collagenous network.
• To investigate the effects of maturation and specimen orientation on skin's mechanical properties.
• To assess the model's suitability for characterizing changes in skin microstructure.

Main Methods:

• Quasi-static uniaxial tensile testing of rat dorsal skin (1-4 months old).
• Specimen preparation from longitudinal and transverse (lateral) orientations relative to the spine.
• Application of a microstructurally based, three-parameter model to experimental data.
• Qualitative comparison with microscopical observations.

Main Results:

• The model indicated increased lateral fiber stiffness with maturation, greater in the lateral than longitudinal direction.
• Maturation led to a shift in the 'heel' region of the stress-strain curve, attributed to reduced fiber crimping.
• The model effectively fitted response curves with a distinct 'heel' region but was less suitable for featureless 'heel' regions.

Conclusions:

• The adapted microstructurally based model shows promise for analyzing skin's collagenous microstructure.
• The model can potentially identify pathological changes in skin's mechanical properties.
• Findings highlight developmental changes in collagen fiber organization and mechanical contribution.