Greven H, Zanger K, Schwinger G
Institut für Zoologie (Morphologie und Zellbiologie, Heinrich-Heine Universität Düsseldorf, Germany.
J Morphol. 1995 Apr;224(1):15-22. doi: 10.1002/jmor.1052240103.
The skin of the aquatic pipid frog, Xenopus laevis, was examined for specific biomechanical features: 1) thickness, 2) maximal strain at break (epsilon f), 3) tensile strength (sigma m), 4) modulus of elasticity (E, stiffness), and 5) the area under the stress-strain curve (W) (breaking energy, toughness). Skin freshly removed from dorsal, ventral, and lateral areas of the body was subjected to uniaxial tension. In both sexes, the dorsal skin is thicker than the ventral. The skin of male frogs was consistently thinner in all body regions than that of females. Most biomechanical parameters showed a considerable range of values in both males (epsilon f = 59-63%, sigma m = 15-16.5 MPa, E = 33.5-38.4 MPa, W = 3.8-4.5 MJ/m3) and females (epsilon f = 102-126%, sigma m = 11.5 MPa, E = 10.4-12 MPa, W = 5.2-6.7 MJ/m3). The disparate epsilon f values in males (low) and females (high) might reflect sexual dimorphism. Static stress-strain curves were typically J-shaped; with the exception of a "toe," the curves rose approximately linearly with increasing strain. The skin of X.laevis, although heterogeneous in structure, possesses features similar to those found in tissues with aligned collagen fibers such as tendons or fish skin. However, in anurans, the skin seems to play a more passive mechanical role during locomotion than in fish.
对非洲爪蟾（Xenopus laevis）这种水生蛙类的皮肤进行了特定生物力学特征的研究：1）厚度，2）断裂时的最大应变（εf），3）拉伸强度（σm），4）弹性模量（E，刚度），以及5）应力-应变曲线下的面积（W）（断裂能，韧性）。从身体背部、腹部和侧面新取下的皮肤进行单轴拉伸试验。在两性中，背部皮肤比腹部皮肤厚。雄蛙所有身体部位的皮肤始终比雌蛙的薄。大多数生物力学参数在雄性（εf = 59 - 63%，σm = 15 - 16.5 MPa，E = 33.5 - 38.4 MPa，W = 3.8 - 4.5 MJ/m³）和雌性（εf = 102 - 126%，σm = 11.5 MPa，E = 10.4 - 12 MPa，W = 5.2 - 6.7 MJ/m³）中都显示出相当大的取值范围。雄性（低）和雌性（高）不同的εf值可能反映了两性异形。静态应力-应变曲线通常呈J形；除了一个“趾部”，曲线随着应变增加大致呈线性上升。非洲爪蟾的皮肤虽然结构不均匀，但具有与肌腱或鱼皮等具有排列整齐胶原纤维的组织相似的特征。然而，在无尾两栖类动物中，皮肤在运动过程中似乎比在鱼类中发挥着更被动的机械作用。
