Studies on solid state physics of keratinised hard tissue: human nail

Abstract

Vertebrate body contains both soft and hard tissues to carry out life processes. Among the hard tissues horn, hoof, feather, claw and nail are the derivatives of the skin. Generally, skin is known as integument. However, the hard tissues, which serve as exoskeleton, can also be referred as integuments as they are highly useful in protecting the body from the environmental influences, acting as thermo- insulators and thermo regulators. In nail, the dorsal unguis is brought and flattened while the sub unguis is reduced to a small remnant, which lies under the tip of the nail. The root of the nail is the place of growth of the unguis and lies embedded in a pocket under the skin called the nail groove or sulcus unguis. The nail bed lies beneath both the nail and its root. The proximal part or matrix is the most important and is concerned in the formation of the nail. Its anterior portion in man may be seen through the base of the transparent thumbnail and forms the whitish lunula, the crescent shaped area. The stratum germinativum above the base of the nail forms a rather rough margin where the nail emerges from the sulcus unguis. As far as organic matter is concerned, the major portion of the nail is made up of albuminoid proteins called keratins. These fibrous proteins are characterized by their very high insolubility in usual protein solvents, because of high sulphur content, which is in the form of cystine. Indeed, biologists have developed specific areas like anatomy, physiology and biochemistry of the calcified tissues, and valuable treatises have been presented as a result of these studies. But no newline7 newlineattention is paid to make systematic investigations on solid state properties of the keratinous hard tissue material such as nail.