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Embryonic Origin (embryonic + origin)
Selected AbstractsEmbryonic origin of mate choice in a lizard with temperature-dependent sex determinationDEVELOPMENTAL PSYCHOBIOLOGY, Issue 1 2006Oliver Putz Abstract Individual differences in the adult sexual behavior of vertebrates are rooted in the fetal environment. In the leopard gecko (Eublepharis macularius), a species with temperature-dependent sex determination (TSD), hatchling sex ratios differ between incubation temperatures, as does sexuality in same-sex animals. This variation can primarily be ascribed to the temperature having direct organizing actions on the brain. Here we demonstrate that embryonic temperature can affect adult mate choice in the leopard gecko. Given the simultaneous choice between two females from different incubation temperatures (30.0 and 34.0°,C), males from one incubation temperature (30.0°,C) preferred the female from 34.0°,C, while males from another incubation temperature (32.5°,C) preferred the female from 30.0°,C. We suggest that this difference in mate choice is due to an environmental influence on brain development leading to differential perception of opposite-sex individuals. This previously unrecognized modulator of adult mate choice lends further support to the view that mate choice is best understood in the context of an individual's entire life-history. Thus, sexual selection results from a combination of the female's as well as the male's life history. Female attractiveness and male choice therefore are complementary. © 2005 Wiley Periodicals, Inc. Dev Psychobiol 48: 29,38, 2006. [source] Characterization of molecular markers to assess cardiac cushions formation in XenopusDEVELOPMENTAL DYNAMICS, Issue 12 2009Young-Hoon Lee Abstract The valves and septa of the mature heart are derived from the cardiac cushions, which develop from discrete swellings in two regions of developing heart tube: the atrioventricular (AV) canal and the ventricular outflow tract (OFT). In higher vertebrates, three distinct lineages contribute to the heart valves and septa, the endocardium, the myocardium, and the cardiac neural crest that will populate the cardiac jelly of the OFT. Very little is known about cardiac cushions development in amphibians. Here, we describe the expression of eight genes during key stages of cardiac cushion development in Xenopus. Among these genes, the Wnt antagonist Frzb1 and the transcription factors Xl-Fli, Sox8, Sox9, and Sox10 are differentially expressed in the mesenchyme of the OFT and AV cushions. These genes can be used in combination with lineage-tracing experiments to determine the embryonic origin of the cardiac cushions mesenchyme in Xenopus. Developmental Dynamics 238:3257,3265, 2009. © 2009 Wiley-Liss, Inc. [source] Muscle stem cells and model systems for their investigationDEVELOPMENTAL DYNAMICS, Issue 12 2007Nicolas Figeac Abstract Stem cells are characterized by their clonal ability both to generate differentiated progeny and to undergo self-renewal. Studies of adult mammalian organs have revealed stem cells in practically every tissue. In the adult skeletal muscle, satellite cells are the primary muscle stem cells, responsible for postnatal muscle growth, hypertrophy, and regeneration. In the past decade, several molecular markers have been found that identify satellite cells in quiescent and activated states. However, despite their prime importance, surprisingly little is known about the biology of satellite cells, as their analysis was for a long time hampered by a lack of genetically amenable experimental models where their properties can be dissected. Here, we review how the embryonic origin of satellite cells was discovered using chick and mouse model systems and discuss how cells from other sources can contribute to muscle regeneration. We present evidence for evolutionarily conserved properties of muscle stem cells and their identification in lower vertebrates and in the fruit fly. In Drosophila, muscle stem cells called adult muscle precursors (AMP) can be identified in embryos and in larvae by persistent expression of a myogenic basic helix,loop,helix factor Twist. AMP cells play a crucial role in the Drosophila life cycle, allowing de novo formation and regeneration of adult musculature during metamorphosis. Based on the premise that AMPs represent satellite-like cells of the fruit fly, important insight into the biology of vertebrate muscle stem cells can be gained from genetic analysis in Drosophila. Developmental Dynamics 236:3332,3342, 2007. © 2007 Wiley-Liss, Inc. [source] Redefining epithelial progenitor potential in the developing thymusEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 9 2007Simona Abstract Cortical and medullary epithelium represent specialised cell types that play key roles in thymocyte development, including positive and negative selection of the T cell repertoire. While recent evidence shows that these epithelial lineages share a common embryonic origin, the phenotype and possible persistence of such progenitor cells in the thymus at later stages of development remain controversial. Through use of a panel of reagents including the putative progenitor marker Mts24, we set out to redefine the stages in the development of thymic epithelium. In the early embryonic day (E)12 thymus anlagen we find that almost all epithelial cells are uniformly positive for Mts24 expression. In addition, while the thymus at later stages of development was found to contain distinct Mts24+ and Mts24, epithelial subsets, thymus grafting experiments show that both Mts24+ and Mts24, epithelial subsets share the ability to form organised cortical and medullary thymic microenvironments that support T cell development, a function shown previously to be lost in the Mts24, cells by E15 when lower cell doses were used. Our data help to clarify stages in thymic epithelial development and provide important information in relation to currently used markers of epithelial progenitors. See accompanying commentary: http://dx.doi.org/10.1002/eji.200737709 [source] Inducible lineage tracing of Pax7-descendant cells reveals embryonic origin of adult satellite cellsGENESIS: THE JOURNAL OF GENETICS AND DEVELOPMENT, Issue 7 2010Christoph Lepper Descendants of E9.5 Pax7-expressing (in red, ,-gal+) central dermomyotome cells contribute to myofibers (in green, MF-20+, a myosin heavy chain protein) in the E16.5 mouse embryo. Nuclei are blue (DAPI). The ,-gal+/MF-20_ cells that are intermingled with myofibers are likely myogenic progenitors. See the article by Lepper and Fan in this issue. [source] Highlighted article: "Inducible lineage tracing of Pax7-descendant cells reveals embryonic origin of adult satellite cells" by lepper and fanGENESIS: THE JOURNAL OF GENETICS AND DEVELOPMENT, Issue 7 2010Article first published online: 13 JUL 2010 No abstract is available for this article. [source] Hepatic progenitor cells, stem cells, and AFP expression in models of liver injuryINTERNATIONAL JOURNAL OF EXPERIMENTAL PATHOLOGY, Issue 5 2006Wolf D. Kuhlmann Abstract Adult hepatocytes and liver-cell progenitors play a role in restoring liver tissue after injury. For the study of progenitor cells in liver repair, experimental models included (a) surgical removal of liver tissue by partial hepatectomy; (b) acute injury by carbontetrachloride; (c) acute injury by d -galactosamine (GalN) and N -nitrosomorpholine (NNM); and (d) chemical hepatocarcinogenesis by feeding NNM in low and high doses. Serological and immunohistological detection of alpha-fetoprotein gene expression served to follow pathways of cellular differentiation. Stem cells were not required in models of surgical removal of parenchyma and in carbon tetrachloride intoxication of adult hepatocytes. In contrast, regeneration of liver occurred through biliary epithelial cells in injuries induced by GalN and NNM. These biliary epithelial cells, collectively called oval cells, are most probably derived from the canals of Hering. Proliferating bile duct cells reached a level of differentiation with reactivation of foetal genes and significant alpha-1-fetoprotein (AFP) synthesis signalling a certain degree of retrodifferentiation with potential stemness. Due to the same embryonic origin of bile ducts and hepatocytes, biliary epithelium and its proliferating progeny (oval cells) have a defined role in liver regeneration as a transit and amplification compartment. In their early proliferation stage, oval cells were heavily engaged in DNA synthesis ([3H]thymidine labelling). Pulse-chase experiments during experimental hepatocarcinogenesis exhibited their development into hepatocytes with high risk for transformation and leading to foci of altered hepatocytes. Hepatocellular carcinomas may arise either from proliferating/differentiating oval cells or from adult hepatocytes; both cell types have stem-like properties. AFP-positive and AFP-negative carcinomas occurred in the same liver. They may represent random clonal origin. The heterogeneity of phenotypic marker (AFP) correlated with a process of retrodifferentiation. [source] Development of the avian lymphatic system,MICROSCOPY RESEARCH AND TECHNIQUE, Issue 2 2001Jörg Wilting Abstract Recently, highly specific markers of the lymphatic endothelium have been found enabling us to reinvestigate the embryonic origin of the lymphatics. Here we present a review of our studies on the development of the lymphatic system in chick and quail embryos. We show that the lymphatic endothelium is derived from two sources: the embryonic lymph sacs and mesenchymal lymphangioblasts. Proliferation studies reveal a BrdU-labeling index of 11.5% of lymph sac endothelial cells by day 6.25, which drops to 3.5% by day 7. Lymphangioblasts are able to integrate into the lining of lymph sacs. Lymphatic endothelial cells express the vascular endothelial growth factor (VEGF) receptors-2 and -3. Their ligand, VEGF-C, is expressed almost ubiquitously in embryonic and fetal tissues. Elevated expression levels are found in the tunica media of large blood vessels, which usually serve as major routes for growing lymphatics. The homeobox gene, Prox1, is expressed in lymphatic but not in blood vascular endothelial cells throughout all stages examined, namely, in developing lymph sacs of day 6 embryos and in lymphatics at day 16. Experimental studies show the existence of lymphangioblasts in the mesoderm, a considerable time before the development of the lymph sacs. Lymphangioblasts migrate from the somites into the somatopleure and contribute to the lymphatics of the limbs. Our studies indicate that these lymphangioblasts already express Prox1. Microsc. Res. Tech. 55:81,91, 2001. © 2001 Wiley-Liss, Inc. [source] Neurofibromatosis type 1 is a disorder of dysplasia: The importance of distinguishing features, consequences, and complications,BIRTH DEFECTS RESEARCH, Issue 1 2010Vincent Michael Riccardi BACKGROUND: The disorder neurofibromatosis type 1 (NF1) is caused by mutations in the NF1 gene, which influences the availability of activated Ras and the latter's control of cellular proliferation. Emphasis on this aspect of NF1 has focused attention on the tumor suppression function of NF1 and thereby displaced attention from the gene's role in initial normal tissue formation, maintenance, and repair. METHODS: Clinical and neuroimaging data systematically compiled over more than 30 years are analyzed to document the involvement of multiple organs and tissues, often with an embryonic origin. In addition, recent literature based on selective knockout mouse experiments is cited to corroborate embryonic dysplasia as an element of NF1 pathogenesis. RESULTS: Tissue dysplasia, both ab initio and as part of tissue maintenance and wound healing, is a key clinical and pathogenetic aspect of NF1 and thereby provides a rationale for differentiating the elements of NF1 into features, consequences, and complications. CONCLUSIONS: NF1 is a histogenesis control gene that also has properties that overlap with those of a tumor suppressor gene. Both its neoplastic and dysplastic manifestations become more amenable to understanding and treatment if they are differentiated at three levels,specifically, features, consequences and complications. Birth Defects Research (Part A), 2010. © 2009 Wiley-Liss, Inc. [source] | |||||||||||||