Immunodetection of type I acidic keratins associated to periderm granules during the transition of cornification from embryonic to definitive chick epidermis |
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| Institution: | 1. Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China;3. Key Laboratory of Theory and Therapy of Muscles and Bones, Ministry of Education, Shanghai University of Traditional Chinese Medicine, Shanghai, People''s Republic of China;2. Department of Pathology and Laboratory Medicine, University of Rochester Medical Center, Rochester, New York;4. Department of Obstetrics and Gynecology, Urology, and Neurobiology and Anatomy, University of Rochester Medical Center, Rochester, New York;6. Center for Musculoskeletal Research, University of Rochester Medical Center, Rochester, New York;5. Oita University, Oita, Japan;1. Department of Entomology, Faculty of Science, Cairo University, Giza, Egypt;2. College of Science and Art, Dammam University, Saudi Arabia;1. Institute of Veterinary Pathology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland;2. Division of Swine Medicine of the Department for Farm Animals, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland;3. Division of Veterinary Epidemiology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland |
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| Abstract: | The change in the modality of cornification from embryonic to definitive epidermis in the chick has been studied using immunocytochemistry and electron microscopy to show that the initial soft cornification based on an acidic type I alpha-keratin transits to a definitive hard cornification based on beta-proteins in the claw, scales and feathers. The first two periderm layers contain acidic keratins associated with periderm granules and participate in a mild form of cornification before shedding of the periderm. The transition from embryonic to adult cornification is best seen in the transitional layers of the claw where numerous periderm granules merge with packets or bundles of corneous beta-proteins. This process is hardly seen in scale and feathers where periderm granules remain most in the periderm or in the feather sheath. Periderm granules disappear in corneocytes generated underneath the periderm in scales or in the transitional layer in claws and are replaced by beta-proteins associated to other types of acidic alpha-keratins. This process produces a mechanically resistant corneous material underneath the softer periderm, adapted to terrestrial demand for mechanical protection in scales and in the dorsal part of the claw, the unguis. In the ventral part of the claw, the sub-unguis, scarce or no beta-proteins are accumulated resulting in a softer corneous layer. The study indicates that specific alpha-keratins form the cytoskeletal framework of definitive corneocytes in claws, scales and feathers, and that specialized corneous beta-proteins are deposited over this framework to produce epidermal layers with higher mechanical resistance. |
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| Keywords: | Chick embryo Claw Epidermis Periderm granules Cornification Immunocytochemistry |
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