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Intermediate Mesoderm (intermediate + mesoderm)
Selected AbstractsXenopus Wnt11b is identified as a potential pronephric inducerDEVELOPMENTAL DYNAMICS, Issue 1 2010Stéphanie Tételin Abstract In this study, we aimed to establish if known wnt signaling molecules could be responsible for inducing early pronephros specification, using a novel and effective in vitro bioassay in Xenopus embryos. Anterior somites have the unique biological activity to signal to unspecified intermediate mesoderm to induce pronephros formation in Xenopus embryos. We have used a molecular candidate gene approach to analyze both canonical and noncanonical wnt expression in isolated anterior and posterior somites and dissected presumptive pronephros, pronephric anlagen, and pronephros from stage 12.5,35 embryos. We have identified potential candidate wnt genes expressed in the right time and place to specify pronephric development. These candidates were then directly tested in an in vitro pronephrogenesis assay based on Holtfreter sandwich cultures. Results revealed that noncanonical wnt11b and wnt11 can induce pronephros formation in vitro. Loss-of-function experiments confirmed that these genes are necessary for normal pronephros development. Developmental Dynamics 239:148,159, 2010. © 2009 Wiley-Liss, Inc. [source] Origin and development of the pronephros in the chick embryoJOURNAL OF ANATOMY, Issue 6 2003Tamiko Hiruma Abstract The process by which the pronephros develops was morphologically examined in chick embryos from Hamburger,Hamilton stage (ST) 8+ to ST34. The intermediate mesoderm, from which the pronephros arises, was first seen as a faint ridge of undifferentiated mesoderm between the segmental plate and lateral plate at ST8+. It formed a cell cord at the level of the 6th to the presumptive 13th somites at ST9 to ST10. This cell cord then separated into dorsal and ventral parts, the former becoming the nephric duct and the latter the tubules by ST14. The primordia of the external glomeruli (PEGs) appeared at ST15 through some epithelial cells protruding in the nephrostome (the opening of the nephric tubule into the body cavity). PEGs formed gradually in the caudal direction until ST18, while the pronephric tubules and PEGs in cranial locations disappeared. At this stage, only a few PEGs remained at the level of the 13th and 14th somites and these developed from ST23 to ST29 to become ultrastructurally similar to the glomeruli of the functional kidney. From these observations in the avian pronephros, we infer that the pronephric duct and tubules both form from a cell cord in the intermediate mesoderm and at the same time, but later develop differently. [source] Vitamin A distribution and content in tissues of the lamprey, Lampetra japonicaTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 2 2004Heidi L. Wold Abstract Vitamin A (retinol and retinyl ester) distribution and content in tissues of a lamprey (Lampetra japonica) were analyzed by morphological methods, namely, gold chloride staining, fluorescence microscopy to detect specific vitamin A autofluorescence, and electron microscopy, as well as high-performance liquid chromatography (HPLC). Hepatic stellate cells showed an abundance of vitamin A stored in lipid droplets in their cytoplasm. Similar cells storing vitamin A were present in the intestine, kidney, gill, and heart in both female and male lampreys. Morphological data obtained by gold chloride staining method, fluorescence microscopy, transmission electron microscopy, and HPLC quantification of retinol were consistent. The highest level of total retinol measured by HPLC was found in the intestine. The second and third highest concentrations of vitamin A were found in the liver and the kidney, respectively. These vitamin A-storing cells were not epithelial cells, but mesoderm-derived cells. We propose as a hypothesis that these cells belong to the stellate cell system (family) that stores vitamin A and regulates homeostasis of the vitamin in the whole body in the lamprey. Fibroblastic cells in the skin and somatic muscle stored little vitamin A. These results indicate that there is difference in the vitamin A-storing capacity between the splanchnic and intermediate mesoderm-derived cells (stellate cells) and somatic and dorsal mesoderm-derived cells (fibroblasts) in the lamprey. Stellate cells derived from the splanchnic and intermediate mesoderm have high capacity and fibroblasts derived from the somatic and dorsal mesoderm have low capacity for the storage of vitamin A in the lamprey. Anat Rec Part A 276A:134,142, 2004. © 2004 Wiley-Liss, Inc. [source] A New Look on the Origin of the Gonad and the Müllerian Duct: the Sturgeon (Acipencer) as a Model for Vertebrate Urogenital DevelopmentANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 2005K. -H. The origin of the vertebrate gonad and the Müllerian duct are still a matter of debate. According to the majority of recent textbooks, the gonad is a product of the proliferating coelothelium and therefore derived from the mesoderm of the lateral plate region. The Müllerian duct grows parallel to the Wolffian duct, but it is not clear to what extent the latter contributes actively to the development of the former. In the last decade, we reinvestigated early gonadogenesis and Müllerian duct development in a number of vertebrate model species using various morphological techniques (TEM, SEM, immunohistochemistry). The conclusion of our studies is that rudimentary or regressing nephrostomial tubules, particularly cells of their nephrostomes, must be regarded as the immediate precursors of the somatic cells of the gonadal crest and the Müllerian infundibular field. According to this concept, both structures are derivatives of the intermediate mesoderm. Nephrostomial tubules are regular components of the primitive pro- and mesonephros. They connect the nephric tubule or the nephric corpuscle to the coelomic cavity and open into the latter by means of a funnel-like mouth, the nephrostome (coelomostome). In the larval sterlet, Acipenser ruthenus, short, segmentally arranged nephrostomial tubules with well-developed nephrostomes are present in the region of the cranial opisthonephros. Cells of the medial nephrostomial lips proliferate, surround the germ cells that have accumulated in this location and form a continuous gonadal crest. Cells of the lateral nephrostomial lips proliferate also, spread out on the coelomic surface, replace the original flat mesothelial cells over the Wolffian duct and the cranial opisthonephros and form the Müllerian infundibular field. At about 28 days, a flat pocket begins to invaginate the infundibular field. This pocket is the primordium of the Müllerian ostium abdominale. The findings in Acipenser can be generalized and transferred to other vertebrates. [source] | ||||||||||