The Experts below are selected from a list of 303 Experts worldwide ranked by ideXlab platform
Raymond Saxod - One of the best experts on this subject based on the ideXlab platform.
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Regulation of the chick cutaneous innervation pattern in retinoic acid-induced ectopic feathers and in the naked neck mutant.
The International journal of developmental biology, 1997Co-Authors: L. Pays, F J Hemming, Raymond SaxodAbstract:In chick skin, nerve fibers develop in a typical network formed by arcades around the base of feathers. In this study, we tried to dissociate the morphogenesis of nerve arcades and feathers, and to clarify the implication of several matricial molecules in these two developmental events. For this purpose, cutaneous nerve pattern and distribution of fibronectin, tenascin, and three epitopes of chondroitin sulfate proteoglycans (CSPGs) have been immunohistologically studied in the skin of the specific Apteria of naked neck chick mutants, which lack feathers in the neck area, and in the tarso-metatarsal zone of retinoic acid-treated embryos where ectopic feathers grow. The presence of feathers was always associated with nerve arcades; no arcades were present in featherless areas. Specific immunofluorescence for tenascin and two epitopes of CSPGs revealed different distributions in the naked-neck neo-Apteria as compared to control Apteria. Moreover, the only difference in matricial composition in ectopic feathers concerned a CSPG isoform, bringing additional evidence that extracellular matrix molecules, and especially some (but not all) CSPGs, are involved both directly and indirectly in the cutaneous nerve pattern development.
L. Pays - One of the best experts on this subject based on the ideXlab platform.
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Regulation of the chick cutaneous innervation pattern in retinoic acid-induced ectopic feathers and in the naked neck mutant.
The International journal of developmental biology, 1997Co-Authors: L. Pays, F J Hemming, Raymond SaxodAbstract:In chick skin, nerve fibers develop in a typical network formed by arcades around the base of feathers. In this study, we tried to dissociate the morphogenesis of nerve arcades and feathers, and to clarify the implication of several matricial molecules in these two developmental events. For this purpose, cutaneous nerve pattern and distribution of fibronectin, tenascin, and three epitopes of chondroitin sulfate proteoglycans (CSPGs) have been immunohistologically studied in the skin of the specific Apteria of naked neck chick mutants, which lack feathers in the neck area, and in the tarso-metatarsal zone of retinoic acid-treated embryos where ectopic feathers grow. The presence of feathers was always associated with nerve arcades; no arcades were present in featherless areas. Specific immunofluorescence for tenascin and two epitopes of CSPGs revealed different distributions in the naked-neck neo-Apteria as compared to control Apteria. Moreover, the only difference in matricial composition in ectopic feathers concerned a CSPG isoform, bringing additional evidence that extracellular matrix molecules, and especially some (but not all) CSPGs, are involved both directly and indirectly in the cutaneous nerve pattern development.
Danielle Dhouailly - One of the best experts on this subject based on the ideXlab platform.
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How and when the regional competence of chick epidermis is established: feathers vs. scutate and reticulate scales, a problem en route to a solution.
The International journal of developmental biology, 2004Co-Authors: Fabrice Prin, Danielle DhouaillyAbstract:Most of the chick body is covered with feathers, while the tarsometatarsus and the dorsal face of the digits form oblong overlapping scales (scuta) and the plantar face rounded nonoverlapping scales (reticula). Feathers and scuta are made of beta-keratins, while the epidermis of reticula and inter-appendage or Apteria (nude regions) express a-keratins. These regional characteristics are determined in skin precursors and require an epidermal FGF-like signal to be expressed. Both the initiation of appendages, their outline and pattern depend on signals from the dermis, while their asymmetry and outgrowth depend on epidermal competence. For example, the plantar dermis of the central foot pad induces reticula in a plantar or feathers in an apteric epidermis, in a hexagonal pattern starting from the medial point. By manipulating Shh levels in the epidermis, the regional appendage type can be changed from scuta or reticula to feather, whereas the inhibition of Wnt7a, together with a downregulation of Shh gives rise to reticula and in extreme cases, Apteria. During morphogenesis of plantar skin, the epidermal expression of En-1, acting as a repressor both of Wnt7a and Shh, is linked to the formation of reticula. Finally, in birds, the complex formation of feathers, which can be easily triggered, even in the extra-embryonic somatopleure, may result from a basic genetic program, whereas the simple formation of scales appears secondarily derived, as requiring a partial (scuta) or total (reticula) inhibition of epidermal outgrowth and beta-keratin gene expression, an inhibition lost for the scuta in the case of feathered feet breeds.
F J Hemming - One of the best experts on this subject based on the ideXlab platform.
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Regulation of the chick cutaneous innervation pattern in retinoic acid-induced ectopic feathers and in the naked neck mutant.
The International journal of developmental biology, 1997Co-Authors: L. Pays, F J Hemming, Raymond SaxodAbstract:In chick skin, nerve fibers develop in a typical network formed by arcades around the base of feathers. In this study, we tried to dissociate the morphogenesis of nerve arcades and feathers, and to clarify the implication of several matricial molecules in these two developmental events. For this purpose, cutaneous nerve pattern and distribution of fibronectin, tenascin, and three epitopes of chondroitin sulfate proteoglycans (CSPGs) have been immunohistologically studied in the skin of the specific Apteria of naked neck chick mutants, which lack feathers in the neck area, and in the tarso-metatarsal zone of retinoic acid-treated embryos where ectopic feathers grow. The presence of feathers was always associated with nerve arcades; no arcades were present in featherless areas. Specific immunofluorescence for tenascin and two epitopes of CSPGs revealed different distributions in the naked-neck neo-Apteria as compared to control Apteria. Moreover, the only difference in matricial composition in ectopic feathers concerned a CSPG isoform, bringing additional evidence that extracellular matrix molecules, and especially some (but not all) CSPGs, are involved both directly and indirectly in the cutaneous nerve pattern development.
Fabrice Prin - One of the best experts on this subject based on the ideXlab platform.
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How and when the regional competence of chick epidermis is established: feathers vs. scutate and reticulate scales, a problem en route to a solution.
The International journal of developmental biology, 2004Co-Authors: Fabrice Prin, Danielle DhouaillyAbstract:Most of the chick body is covered with feathers, while the tarsometatarsus and the dorsal face of the digits form oblong overlapping scales (scuta) and the plantar face rounded nonoverlapping scales (reticula). Feathers and scuta are made of beta-keratins, while the epidermis of reticula and inter-appendage or Apteria (nude regions) express a-keratins. These regional characteristics are determined in skin precursors and require an epidermal FGF-like signal to be expressed. Both the initiation of appendages, their outline and pattern depend on signals from the dermis, while their asymmetry and outgrowth depend on epidermal competence. For example, the plantar dermis of the central foot pad induces reticula in a plantar or feathers in an apteric epidermis, in a hexagonal pattern starting from the medial point. By manipulating Shh levels in the epidermis, the regional appendage type can be changed from scuta or reticula to feather, whereas the inhibition of Wnt7a, together with a downregulation of Shh gives rise to reticula and in extreme cases, Apteria. During morphogenesis of plantar skin, the epidermal expression of En-1, acting as a repressor both of Wnt7a and Shh, is linked to the formation of reticula. Finally, in birds, the complex formation of feathers, which can be easily triggered, even in the extra-embryonic somatopleure, may result from a basic genetic program, whereas the simple formation of scales appears secondarily derived, as requiring a partial (scuta) or total (reticula) inhibition of epidermal outgrowth and beta-keratin gene expression, an inhibition lost for the scuta in the case of feathered feet breeds.