The bHLH transcription factor dHAND is required for establishment of SHH signaling by the limb bud organizer in posterior mesenchyme, a step crucial to development vertebrate paired appendages. We show that transcriptional repressor GLI3 restricts expression mesenchyme prior activation mouse buds. dHAND, turn, excludes anterior genes such as Gli3 and Alx4 from mesenchyme. Furthermore, genetic interaction directs SHH/FGF feedback loop restricting BMP antagonist GREMLIN posteriorly. These...

Growth of limb cells in culture conditions with subsequent vivo transplantation allows the dissection patterning.

dHAND is a basic helix-loop-helix (bHLH) transcription factor essential for cardiovascular development. Here we analyze its pattern of expression and functional role during chick limb was observed in the lateral plate mesoderm prior to emergence buds. Coincident with initiation, became restricted posterior half bud. Experimental procedures that caused mirror-image duplications resulted along anterior-posterior axis. Retroviral overexpression bud produced preaxial polydactyly, corresponding...

Abstract Cell death and cell proliferation are basic cellular processes that need to be precisely controlled during embryonic development. The developing vertebrate limb illustrates particularly well how correct morphogenesis depends on the appropriate spatial temporal balance between proliferation. Precise knowledge of patterns development is required understand their modifications may contribute generation great diversity phenotypes result from spontaneous mutations or induced genetic...

We have analyzed a new limb mutant in the chicken that we name oligozeugodactyly (ozd). The limbs of this longitudinal postaxial defect, lacking posterior element zeugopod (ulna/fibula) and all digits except digit 1 leg. Classical recombination experiments show mesoderm is defective tissue layer ozd buds. Molecular analysis revealed develop absence Shh expression, while other organs express normally. Neither Ptc1 nor Gli1 are detectable However, Bmp2 dHAND expressed wing leg bud mesoderm,...

ABSTRACT In this work we have attempted to characterize the programmed cell death process in chick embryonic interdigital tissue. Interdigital is a prominent phenomenon during limb development and has role of sculpturing digits. Morphological changes regressing tissue studied by light, transmission scanning electron microscopy were correlated with occurrence internucleosomal DNA fragmentation, evaluated using agarose gels. Programming was also analyzed testing chondrogenic potential...

Abstract The ventricular fiber architecture has been studied anatomically and histologically in 25 human hearts. Special attention paid to the form of insertion myocardial fibers existence or nonexistence an independent system for each ventricle. Three different layers—superficial (subepicardial), middle, deep (subendocardial)—have distinguished according direction through mass. All are common both ventricles with exception a thick middle layer peculiar left tendinous cords, central fibrous...

Abstract Removal of the posterior wing bud leads to massive apoptosis remaining anterior mesoderm. We show here that this finding correlates with an increase in level repressor form Gli3 protein, due absence Sonic hedgehog (Shh) protein signaling. Therefore, we used mesoderm as a model system analyze relationship between and developing limb. With increased Gli3R levels, demonstrate concomitant Bmp4 expression signaling deprived Shh Several experimental approaches can be prevented by...

The pattern and structure of the blood vessels interdigital spaces leg bud have been studied by means Indian ink injections transmission electron microscopy in chick duck embryos. results show that necrotic process responsible for freeing digits is followed regression vessels. In webbed foot duck, processes are not vascular regression. Transmission microscopic studies both immature structures lacking basal lamina. Dead cells presumably endothelial origin were detected lumen regressing but...

Abstract eHAND is a bHLH transcription factor with important functions during embryogenesis. Here, we report that has dynamic pattern of expression limb development. In chick embryos, first observed in the ventral mesoderm emerging limb. Its then restricted to an anteroventral area at mid‐level proximodistal axis. At later stages, autopod encompassing tendons digits. mouse only domain conserved, early not being detectable and late differing clearly from chick. A constant feature all areas...

Fine structural study of interdigital membranes during formation the digits duck foot reveals that necrosis is accompanied by a high deposition collagenous material in epithelio-mesenchymal interface, rupture basal lamina and detachment ectodermal cells into amniotic sac. These changes are similar to those observed regressing membrane chick although their intensity temporal extension less pronounced duck. It suggested these account for disappearance marginal zone membranes. The possible...

ABSTRACT There is recent evidence showing that in addition to the well-known mesenchymal necrotic mechanism involved disappearance of interdigital membranes, ectodermal tissue may also play an active role formation free digits most vertebrates. Ultrastructural study regressing membrane chick leg revealed significant changes at epitheliomesenchymal interface. Disruptions basal lamina and intense deposition collagenous material were conspicuous observed extracellular matrix. In cells showed...

ABSTRACT In an attempt to clarify the mechanism of production syndactyly induced by Janus Green B (JGB) we have studied morphology and structural modifications chick embryo leg bud after JGB administration means (1) neutral red vital staining, (2) whole-mount cartilage staining β) light microscopy transmission scanning electron microscopy. The results show that well-known inhibition interdigital cell death is accompanied a precocious alteration epithelial tissue especially...