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Normal Morphogenesis (normal + morphogenesi)
Selected AbstractsDan is required for normal morphogenesis and patterning in the developing chick inner earDEVELOPMENT GROWTH & DIFFERENTIATION, Issue 1 2007Takahiro Yamanishi During vertebrate inner ear development, compartmentalization of the auditory and vestibular apparatuses along two axes depends on the patterning of transcription factors expressed in a region-specific manner. Although most of the patterning is regulated by extrinsic signals, it is not known how Nkx5.1 and Msx1 are patterned. We focus on Dan, the founding member of the Cerberus/Dan gene family that encodes BMP antagonists, and describe its function in morphogenesis and patterning. First, we confirmed that Dan is expressed in the dorso-medial region of the otic vesicle that corresponds to the presumptive endolymphatic duct and sac (ed/es). Second, we used siRNA knockdown to demonstrate that depletion of Dan induced both a severe reduction in the size of the ed/es and moderate deformities of the semicircular canals and cochlear duct. Depletion of Dan also caused suppression of Nkx5.1 in the dorso-lateral region, suppression of Msx1 in the dorso-medial region, and ectopic induction of Nkx5.1 and Msx1 in the ventro-medial region. Most of these phenotypes also appeared following misexpression of the constitutively active form of BMP receptor type Ib. Thus, Dan is required for the normal morphogenesis of the inner ear and, by inhibiting BMP signaling, for the patterning of the transcription factors Nkx5.1 and Msx1. [source] A Transgenic Insertional Inner Ear Mutation on Mouse Chromosome 1,THE LARYNGOSCOPE, Issue 4 2000Rick A. Friedman MD Abstract Objectives/Hypothesis To clone and characterize the integration site of an insertional inner ear mutation, produced in one of fourteen transgenic mouse lines. The insertion of the transgene led to a mutation in a gene(s) necessary for normal development of the vestibular labyrinth. Study Design Molecular genetic analysis of a transgene integration site. Methods Molecular cloning, Southern and northern blotting, DNA sequencing and genetic database searching were the methods employed. Results The integration of the transgene resulted in a dominantly inherited waltzing phenotype and in degeneration of the pars superior. During development, inner ear fluid homeostasis was disrupted. The integration consisted of the insertion of a single copy of the transgene. Flanking DNA was cloned, and mapping indicated that the genomic DNA on either side of the transgene was not contiguous in the wild-type mouse. Localization of unique markers from the two flanks indicated that both were in the proximal region of mouse chromosome 1. However, in the wild-type mouse the markers were separated by 6.3 cM, indicating a sizable rearrangement. Analysis of the mutant DNA indicated that the entire region between the markers was neither deleted nor simply inverted. Conclusions These results are consistent with a complex rearrangement, including at least four breakpoints and spanning at least 6.3 cM, resulting from the integration of the transgene. This genomic rearrangement disrupted the function of one or more genes critical to the maintenance of fluid homeostasis during development and the normal morphogenesis of the pars superior. [source] Normal Development of the Muscular Region of the Interventricular Septum.ANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 3 2009Summary In a first paper, we concluded that the muscular region of the interventricular septum is developed by the trabecular branches and showed evidence that the developing interventricular septum elongates in a direction opposite to that of atria. Nevertheless, to date the literature is lacking precise information on the importance of myocardial proliferation not only in this process but also in the morphogenesis of the ventricular cavities. The aim of this study was to determine the spatial and temporal distribution of high-intensity foci of cycling myocytes in the ventricular region of the heart of chicken embryos during cardiac septation. Histological studies, detection of the proliferating cell nuclear antigen by light and confocal microscopy and flow cytometric analysis were carried out. The results corroborate that the developing interventricular septum grows in a direction opposite to that of atria. A remoulding mechanism that results in fenestrated trabecular sheets and trabecular branching is discussed. Our findings allowed us to summarize the normal morphogenesis of the muscular region of the interventricular septum in a way that is different from that suggested by other researchers. [source] | ||||||||||