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Ultrastructure and physical properties of an adhesive surface, the toe pad epithelium of the tree frog, Litoria caerulea White
- Source :
- Journal of Experimental Biology. 212:155-162
- Publication Year :
- 2009
- Publisher :
- The Company of Biologists, 2009.
-
Abstract
- SUMMARY Knowledge of both surface structure and physical properties such as stiffness and elasticity are essential to understanding any adhesive system. In this study of an adhesion surface in the tree frog, Litoria caerulea White, a variety of techniques including atomic force microscopy were used to investigate the microstructure and properties of an epithelium that adheres through wet adhesion. Litoria toe pads consist of a hexagonal array of flat-topped epithelial cells, separated by mucus-filled channels. Under an atomic force microscope, this `flat' surface is highly structured at the nanoscale, consisting of a tightly packed array of columnar nanopillars (described as hemidesmosomes by previous authors), 326±84 nm in diameter, each of which possesses a central dimple 8±4 nm in depth. In fixed tissue (transmission electron microscopy), the nanopillars are approximately as tall as they are broad. At the gross anatomical level, larger toe pads may be subdivided into medial and lateral parts by two large grooves. Although the whole toe pad is soft and easily deformable, the epithelium itself has an effective elastic modulus equivalent to silicon rubber (mean Eeff=14.4±20.9 MPa; median Eeff=5.7 MPa), as measured by the atomic force microscope in nanoindentation mode. The functions of these structures are discussed in terms of maximising adhesive and frictional forces by conforming closely to surface irregularities at different length scales and maintaining an extremely thin fluid layer between pad and substrate. The biomimetic implications of these findings are reviewed.
- Subjects :
- Materials science
Friction
Surface Properties
Physiology
Aquatic Science
Microscopy, Atomic Force
Epithelium
law.invention
Microscopy, Electron, Transmission
Biomimetics
Dimple
law
Elastic Modulus
Animals
Composite material
Molecular Biology
Elastic modulus
Ecology, Evolution, Behavior and Systematics
Nanopillar
biology
Adhesiveness
Anatomy
Toes
Litoria caerulea
Nanoindentation
Microstructure
biology.organism_classification
Insect Science
Animal Science and Zoology
Adhesive
Anura
Electron microscope
Research Article
Subjects
Details
- ISSN :
- 14779145 and 00220949
- Volume :
- 212
- Database :
- OpenAIRE
- Journal :
- Journal of Experimental Biology
- Accession number :
- edsair.doi.dedup.....61d88445de9f232a55a4cd8f93eabe3f
- Full Text :
- https://doi.org/10.1242/jeb.019232