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Skeletal muscle fibers form during two periods of development and differ biochemically, functionally and in their morphology. Primary fibers develop in the rat hindlimb during Days 14 to 16 of embryogenesis. These fibers are subsequently surrounded by secondary fibers that eventually constitute the bulk of muscle mass in the limbs. We have used the(More)
The epiblast layer of the chick embryo gives rise to all embryonic tissues. In vitro analyses were carried out to determine whether epiblast cells could form skeletal muscle prior to entry into the primitive streak. Epiblasts were separated from the mesoderm, hypoblast, and primitive streak, dissociated to produce a single cell suspension, and plated at(More)
Epiblast cells downregulate E-cadherin and upregulate N-cadherin as they ingress through the primitive streak and when placed in culture. The factors that promote the alteration in cadherin expression during gastrulation are unknown. The effects of hepatocyte growth factor/scatter factor (HGF/SF) on cadherin expression were tested in cultures of prestreak(More)
MyoD expression is thought to be induced in somites in response to factors released by surrounding tissues; however, reverse transcription-PCR and cell culture analyses indicate that myogenic cells are present in the embryo before somite formation. Fluorescently labeled DNA dendrimers were used to identify MyoD expressing cells in presomitic tissues in(More)
The establishment of cells with myogenic or chondrogenic potential is temporally and spatially separated from terminal differentiation in the developing chick embryo. Both cell types arise from tissue adjacent to the neural tube and notochord, the paraxial mesoderm. A cell culture system was developed in order to study the maturation and differentiation of(More)
We investigated an alternative pathway for emergence of the mesenchymal cells involved in epithelial sheet wound healing and a source of myofibroblasts that cause fibrosis. Using a mock cataract surgery model, we discovered a unique subpopulation of polyploid mesenchymal progenitors nestled in small niches among lens epithelial cells that expressed the(More)
Cells with the potential to form skeletal muscle are present in the chick embryo prior to gastrulation. Muscle differentiation begins after gastrulation within the somites. The role of cadherin-mediated adhesion in the commitment and differentiation of skeletal muscle precursor cells was examined by analyzing the expression of cell-cell adhesion molecules(More)
Myo/Nog cells are essential for eye development in the chick embryo and respond to injury in adult tissues. These cells express mRNA for the skeletal muscle specific transcription factor MyoD, the bone morphogenetic protein (BMP) inhibitor Noggin and the cell surface protein recognized by the G8 monoclonal antibody (mAb). In this study, we determined that(More)
MyoD mRNA is expressed in a subpopulation of cells within the embryonic epiblast. Most of these cells are incorporated into somites and synthesize Noggin. Ablation of MyoD-positive cells in the epiblast subsequently results in the herniation of organs through the ventral body wall, a decrease in the expression of Noggin, MyoD, Myf5, and myosin in the(More)
The epiblast of the chick embryo gives rise to the ectoderm, mesoderm, and endoderm during gastrulation. Previous studies revealed that MyoD-positive cells were present throughout the epiblast, suggesting that skeletal muscle precursors would become incorporated into all three germ layers. The focus of the present study was to examine a variety of organs(More)