The main function of the integument of vertebrates is to separate and protect the organism from the environment. Present-day vertebrates display profound alterations of the skin related to protection which have developed during a long history of evolution. Modifications of the epidermis that is in direct contact with the environment have been essential to maintain stability of the interior milieu in water, in the air and on land, and to provide protection against the perils of the environment. Development of keratinized epidermal appendages, such as cornified “teeth” in lampreys and breeding tubercles in fishes; scales, claws and shell of reptiles; scales, claws, beak and feathers of ayes; and scales, claws, hooves, nails, quills, wool, hairs and horns of mammals, have been indispensible not only for protective purposes but also for mating behavior, locomotion, predation, homoiothermy etc. Evolution of these keratinized structures has been extensively studied by classical histological methods, but the concepts are speculative rather than factual, including development of feathers from scales and hairs from interscale epidermis (Spearman 1964). Evolution of epidermal appendages is not yet understood.
KeywordsEpidermal Cell Stratum Corneum Polar Lipid Lipid Droplet Intercellular Space
Unable to display preview. Download preview PDF.
- Jenkinson McEwan D, Roberts RJ (1980) (eds) Surface ecosystems and the interactions within them which overcome skin defence mechanisms. Proc R Soc Edinb 79B: 213Google Scholar
- Matoltsy AG (1977) The membrane of horny cells. In: Seiji M, Bernstein IA (eds) Biochemistry of cutaneous epidermal differentiation. Univ Tokyo Press, Tokyo, pp 93–109Google Scholar
- McLaughlin PJ, Dayhoff MO (1969) Evolution of species and proteins In: Dayhoff MO (ed) Atlas of protein sequence and structure. Natl Biochem Res Found Maryland, vol 4: 39Google Scholar
- Mittal AK, Banerjee TK (1980) Keratinization versus mucus secretion in fish epidermis. In: Spearman RIC, Riley PA (eds) The skin of vertebrates. Academic Press, London New York, pp 1–12Google Scholar
- Spearman RIC (1964) The evolution of mammalian keratinized structures. In: Ebling FJ (ed) Symp Zool Soc Lond 12. Academic Press, London New York, pp 67Google Scholar
- Stettenheim P (1972) The skin of birds. In: Farner DS, King JR (eds) Avian biology, vol II. Academic Press, London New York, pp 1–63Google Scholar
- Warnke U (1979) Information transmission by means of electrical biofields. In: Popp FA, Becker G, König HL, Peschka W (eds) Electromagnetic bio-information. Urban and Schwarzenberg, München Wien Baltimore, pp 55–79Google Scholar