Ectodermal cell fate

Cord blood has long been used as a source of MSCs for bone marrow transplantation. The stem cell compartment is more abundant and less mature in cord blood than in bone marrow. Moreover, MSCs in cord blood have a higher proliferative potential because of their extended lifespan and longer telomeres [91-94]. Not only can cord-blood MSCs be harvested without morbidity to the donor, but they also display a robust in vitro capacity for directable or spontaneous differentiation into mesodermal, endodermal, and ectodermal cell fates. Cord-blood MSCs are CD45 and HLA-II and can be expanded without losing their pluripotency. Therefore, cord blood is also undergoing preclinical evaluation as a possible easily accessible source of multipotent cells. 

Activation of Hematopoiesis and Vasculogenesis in the Mouse Embryo Induction and Reprogramming of Ectodermal Cell Fate by Signals from Primitive Endoderm... 

Shh produced In the notochord Induces floor-plate development. The floor plate, In turn, produces Shh, which forms a ventral —> dorsal gradient that Induces additional cell fates. In the dorsal region, BMP proteins secreted from the overlying ectoderm cells act In a similar fashion to create dorsal cell fates. [See I M. Jessell, 2000, Nature Rev. Genet 1 20.]... 

Once the three germ layers are established, they subsequently divide into cell populations with different fates. For instance, the ectoderm becomes divided into those cells that are precursors to the skin epithelium and those that are precursors to the nervous system. There appears to be a progressive restriction in the range of cell types that can be formed from stem cells and precursor cells as development proceeds. An early embryonic stem cell, as we ve seen, can form every type of cell, an ectodermal cell has a choice between neural and epidermal fates, while a keratinocyte precursor can form skin but not neurons. 

Fly neuroblasts, which are stem cells, arise from a sheet of ectoderm cells that is one cell thick. As in vertebrates, the Drosophila ectoderm forms both epidermis and the nervous system, and many ectoderm cells have the potential to assume either a neural or epidermal fate. Under the control of genes that become active only in certain cells, some of the cells increase in size and begin to loosen from the ectodermal layer. At this point, the delaminating cells use Notch signal-... 

Tam PPL (1989) Regionalisation of mouse embryonic ectoderm allocation of prospective ectodermal tissue during gastrulation. Development 107 55-67. Trainor PA, Tan S-S, Tam PPL (1994) Cranial paraxial mesoderm regionalisation of cell fate and impact upon craniofacial development in mouse embryos. Development 120 2397-2408. 

Turner, D. L. and Weintraub, H. (1994) Expression of achaete-scute homolog 3 in Xenopus embryos converts ectodermal cells to a neural fate. Genes Dev. 8, 1434-1447. 

Respecification of Anterior Ectoderm to Hematopoietic and Endothelial Cell Fates by Visceral Endoderm... 

Might the molecules responsible for respecification of cell fate observed in the reprogramming assay be distinct from those involved in activation of hematopoiesis from nascent posterior mesoderm in vfvol The induction (epiblast explant) assay presumably reflects what occurs in vivo, while the reprogramming (anterior ectoderm) assay reflects the potential activity of visceral endoderm signals. Anterior ectoderm is normally fated to form neurectoderm, not blood or endothelial cells. 

Vertebrate limbs grow from small buds composed of an inner mass of mesoderm cells surrounded by a sheath of ectoderm. Secreted signals from both cell layers coordinate limb development and instruct cells about their proper fates within limbs. The first signal, fibroblast growth factor 10 (FGFIO) is secreted from the lateral trunk mesoderm and initiates outgrowth of a limb from specific regions of the em-... 

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