4/17/2023 0 Comments Vivo con el alpha pdf gratis![]() The fiber extremities form a specialized contact surface reminiscent of a myotendinous junction (MTJ), while at the equatorial level the sarcolemma (solid black line) can harbor a postsynaptic element (brown) indicating post-neuromuscular junction (NMJ) assembly. In the central scheme, the elongated myofiber contains aligned striated myofibril bundles composed of various MyHCs (yellows), dystrophin in a subsarcolemmal position (thin irregular black line), aligned mitochondria (green), myonuclei (gray) and nascent T-tubule network (light blue lines). Schematic of a myofiber (center) and the corresponding representative features detectable by immunohistochemistry on skeletal myofibers differentiated from mESCs. Directed differentiation into skeletal muscle occurs according to slightly different timelines using mESCs as compared with hPSCs (bottom).Ĭellular features of PSC-derived skeletal myofibers. In some instances, the cellular events occurring during differentiation remain largely unclear (dashed line). Direct reprogramming approaches aim to bypass early developmental stages by overexpressing a myogenic regulator, chiefly Pax3/7 or MyoD (iPAX3/7, iMYOD). The sequence of developmental stages and important signaling pathways associated with each stage are shown. Directed differentiation approaches aim to recapitulate the developmental stages of paraxial mesoderm specification and differentiation by manipulating signaling pathways such as Wnt and BMP. ![]() A comparison of the approaches to generating skeletal muscle from PSCs is shown in the middle. The sequence of the differentiation stages of mESCs and hPSCs into skeletal muscle and their corresponding markers is shown from left to right (top). Comparison of strategies to generate skeletal muscles from PSCs. Skeletal myogenesis from pluripotent stem cells. ao, dorsal aorta IM, intermediate mesoderm smt, somatopleura spl, splanchnopleura n, notochord nt, neural tube D, dorsal L, lateral M, medial V, ventral. The respective contributions of the various mesodermal subtypes to the adult tissues are listed beneath each tissue type for example, the notochord contributes to the formation of the nucleus pulposus in the adult. Concomitantly, neural crest (nc, gray) delaminates from the dorsal neural tube and, while migrating ventrally, contacts dermomyotomal cells to promote myogenic induction through Notch activation and β-catenin stabilization (asterisk). BMP signaling (not shown) produced by the LPM transiently inhibits somitic lineage differentiation. The ventral somite undergoes an epithelial-to-mesenchyme transition to form the sclerotome (scl, blue). Cells delaminate from the VLL to give rise to the myogenic progenitors of the limbs that migrate into the LPM. The dermomyotome also gives rise to the myotome (m, orange), which forms beneath from the four DM lips. Dorsally, the somite differentiates into the dermomyotome (DM, red), which can be further subdivided into central dermomyotome (cDM), dorsomedial lip (DML) and ventrolateral lip (VLL). (B) Spatial relationship between the differentiated somite and the surrounding structures. Ventrally, Shh secreted from the midline plays a major role in sclerotome induction. ![]() ![]() Dorsally, Wnt signaling is required for dermomyotome specification, while BMP signaling produced by the lateral plate mesoderm (LPM) inhibits the differentiation of somitic lineages. Each epithelial somite is patterned into dorsoventral, mediolateral and anteroposterior compartments by signaling factors secreted by the surrounding tissues. The mesodermal subtypes are shown, as well as the future epaxial and hypaxial domains. (A) Spatial relationship between the epithelial somite and the surrounding structures. ![]()
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