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Skin Pattern (skin + pattern)
Selected AbstractsLight and scanning microscopic studies of integument differentiation in the grass snake Natrix natrix L. (Lepidosauria, Serpentes) during embryogenesisACTA ZOOLOGICA, Issue 1 2009Elwira Swad Abstract We analysed the differentiation of body cover in the grass snake (Natrix natrix L.) over the full length of the embryo's body at each developmental stage. Based on investigations using both light and scanning electron microscopes, we divided the embryonic development of the grass snake integument into four phases. The shape of the epidermal cells changes first on the caudal and ventral parts of the embryo, then gradually towards the rostral and dorsal areas. In stage V on the ventral side of the embryo the gastrosteges are formed from single primordia, but on the dorsal side the epidermis forms the scale primordia in stage VII. This indicates that scalation begins on the ventral body surface, and spreads dorsally. The appearance of melanocytes between the cells of the stratum germinativum in stage VII coincides with changes in embryo colouration. The first dermal melanocytes were detected in stage XI so in this stage the definitive skin pattern is formed. In the same stage the epidermis forms the first embryonic shedding complex and the periderm layer begins to detach in small, individual flakes. This process coincides with rapid growth of the embryos. [source] The reaction-diffusion system: a mechanism for autonomous pattern formation in the animal skinGENES TO CELLS, Issue 6 2002Shigeru Kondo How do animals acquire their various skin patterns? Although this question may seem easy, in fact it is very difficult to answer. The problem is that most animals have no related structures under the skin; therefore, the skin cells must form the patterns without the support of a prepattern. Recent progress in developmental biology has identified various molecular mechanisms that function in setting the positional information needed for the correct formation of body structure. None of these can explain how skin pattern is formed, however, because all such molecular mechanisms depend on the existing structure of the embryo. Although little is known about the underlying molecular mechanism, many theoretical studies suggest that the skin patterns of animals form through a reaction-diffusion system,a putative ,wave' of chemical reactions that can generate periodic patterns in the field. This idea had remained unaccepted for a long time, but recent findings on the skin patterns of fish have proved that such waves do exist in the animal body. In this review, we explain briefly the principles of the reaction-diffusion mechanism and summarize the recent progress made in this area. [source] Cutis marmorata telangiectatica congenita and chronic autoimmune urticaria in a young manTHE JOURNAL OF DERMATOLOGY, Issue 3 2007Lucilla MELANI ABSTRACT A 20-year-old man with mental impairment, was referred to us for evaluation of recurring idiopathic urticaria episodes, characterized by a diffuse spreading of wheals and severe itching lacking response to traditional antihistamines. Upon physical examination, he showed a persistent, generalized, reticular, red-bluish vascular skin pattern in association with diffuse arborizing telangiectasias. Such lesions were present from an early age. Laboratory and instrumental tests, performed in order to exclude any condition associated with livedo did not evidence pathological results. He was found to be positive for antinuclear autoantibodies (ANA; 1:640). Histopathologically, numerous dilated capillary vessels associated with sparse extravasated erythrocytes were observed in the upper dermis. We performed an autologous serum skin test (ASST), which resulted in a positive, suggesting an autoimmune basis of the condition. On the basis of clinical and histopathological findings, and in the absence of other clinical and laboratory data suggesting other neoplastic, immunological or systemic diseases, the diagnosis of cutis marmorata telangiectatica congenita (CMTC) associated with chronic autoimmune urticaria (CAIU) was made. CMTC is a rare congenital vascular disorder, consisting in an anomalous, persistent, red-bluish marbling of the skin, that can be associated with a wide spectrum of cutaneous and extracutaneous anomalies. In our case, neither physical examination nor instrumental investigation demonstrated any of these anomalies, with the exception of cognitive impairment. We report this case because of the rarity of a diagnosis of CMTC in an adult patient, because this condition has almost always previously been diagnosed in infancy, or it comes to observation because of the presence of associated disorders, as in our case for chronic urticaria. [source] The reaction-diffusion system: a mechanism for autonomous pattern formation in the animal skinGENES TO CELLS, Issue 6 2002Shigeru Kondo How do animals acquire their various skin patterns? Although this question may seem easy, in fact it is very difficult to answer. The problem is that most animals have no related structures under the skin; therefore, the skin cells must form the patterns without the support of a prepattern. Recent progress in developmental biology has identified various molecular mechanisms that function in setting the positional information needed for the correct formation of body structure. None of these can explain how skin pattern is formed, however, because all such molecular mechanisms depend on the existing structure of the embryo. Although little is known about the underlying molecular mechanism, many theoretical studies suggest that the skin patterns of animals form through a reaction-diffusion system,a putative ,wave' of chemical reactions that can generate periodic patterns in the field. This idea had remained unaccepted for a long time, but recent findings on the skin patterns of fish have proved that such waves do exist in the animal body. In this review, we explain briefly the principles of the reaction-diffusion mechanism and summarize the recent progress made in this area. [source] | ||||||||||