Comparative equilibrium mechanical properties of bovine and lamprey cartilaginous tissues

Abstract

SUMMARY In contrast to all other vertebrate cartilages, the major extracellular matrix protein of lamprey cartilages is not collagen. Instead, there exists a unique family of noncollagenous structural proteins, the significance of which is not completely understood. A custom-built uniaxial testing apparatus was used to quantify and compare equilibrium stress-relaxation behavior(equilibrium moduli, stress decay behavior, recovery times and relaxation times) of (1) lamprey pericardial cartilages with perichondria tested in tension (young adult and aged), (2) annular cartilages without perichondria tested in compression (young adult and aged) and (3) bovine auricular cartilage samples without perichondria tested in both tension and compression. Results of this study demonstrated that all cartilages were highly viscoelastic but with varying relaxation times; approximately 120 min for annular and pericardial cartilages and 30 min for bovine auricular cartilages. For mean equilibrium moduli, young adult lamprey annular cartilages (0.71 MPa)and pericardial cartilages (2.87 MPa) were found to be statistically different. The mean moduli of all bovine auricular cartilages were statistically identical to lamprey cartilages except in the case of aged adult pericardial cartilages, which were statistically larger than all other cartilages at 4.85 MPa. Taken together, the results of this study suggest that lamprey cartilages are able to exhibit mechanical properties largely similar to those of mammalian cartilages despite unique structural proteins and differences in extracellular matrix organization.

Evolutionary origin of synovial joints

“…However, the mineralized as well as non-mineralized cartilaginous skeleton of elasmobranchs can be as stiff and strong as mammalian trabecular bone owing to its collagen and glycosaminoglycan content [37, 51, 52], suggesting that their bendability is not superior to bony skeletons. In comparison, lamprey fibrocartilage compares with mammalian articular cartilage in its mechanical properties [53], and therefore, it is comparatively softer than chondrichthyan cartilage. Lamprey cartilage also expresses lamprin, an elastin-like protein, in their nasal, branchial, and pericardial cartilage, imparting enhanced sketelal flexibility [54].…”

Mechanical properties of cocoons constructed consecutively by a single silkworm caterpillar, Bombyx mori

“…Five or six specimens of each thin cocoon were performed to yield an averaged result. The force-displacement curves were recorded automatically, from which the tensile moduli and tensile strengths of the cocoon specimens can be determined with stress-strain analysis [16].…”