Uncommited cell

The term uncommitted cell is ambiguous. For opponents of the precommitment hypothesis it may mean a pluripotential or totipotential cell which may gain its antibody-synthesizing capacity as a consequence of contact with antigen. Proponents of the precommitment hypothesis accept that immature uncommitted cells do exist, but they postulate that uncommitted cells cannot be triggered by antigen. 

Uncommitted Migration Committed Terminally-differentiated Neural Crest Cell Determination Progenitors Derivatives... 

Figure 5.2 All types of blood cells are formed from uncommitted blood (hematopoietic) stem cells in a process called differentiation. Specific protein factors drive the development of erythrocytes (red blood cells), platelets, and the w/hite blood cells including neutrophils and eosinophils, basophils, all with multi-lobed nuclei, and the mononuclear monocytes and lymphocytes that provide specific protein and cellular defenses to the body.

Fig. 6.11 The way is shown from a pluripotent stem cell to a multipotent, uncommitted colony-forming cell, to a committed colony-forming cell (CFO with an already restricted repertoire, and finally to a terminally differentiated blood cell. (For more information, see also ref. 30.)...

Akai PS, Mosmaun TR (1999) Primed and replicating but uncommitted T helper precursor cells show kinetics of differentiation and commitment similar to those of naive T helper cells. Microbes hifect 1 51—58. 

Fig. 1. Neurulation. (A) During the first phase of neurulation, naive uncommitted ectoderm is induced to form neural plate tissue via BMP inhibitory signals (noggin, chordin, follistatin) secreted from the underlying mesoderm. (B) During the second phase of neurulation the two halves of the open neural plate begin to curl up to form a hollow neural tube. During this time neural crest cells (ncc), which express Snail are induced at the neural plate border and begin to migrate in response to Wnt6 and Bmp expression in the surface ectoderm and dorsal neural tube respectively. (See Color Insert.)...

This suggests that cells that are committed to switch can be induced to go to C7l rather than Cy3. But even the detailed analysis of Layton et al. [9] could not distinguish between induction of the specific switch to IgGl and the selection of precursor cells committed to the IgGl isotype, because an identifying marker for the latter cells was missing. In any case, the isotype commitment would have had occurred after activation of the yet uncommitted splenic B cell. 

The bone marrow functions as a primary lymphoid organ and serves as the principal source of uncommitted stem cells, including both myeloid and ery-throid precursor cells. The bone marrow architecture is highly organized and complex, consisting of a matrix or cellular stroma derived from local mesenchymal cells, as well as cells of hemopoietic parenchyma that are descendants... 

The initial phase of neural development is characterized by cellular proliferation (Cowan, 1979). As cell numbers increase, the epithelium thickens becoming separated into a ventricular zone and a less well defined and transient outer region, the subventricular zone, which becomes populated by committed precursor cells. In mammalian development, lineage commitment of CNS neural precursor cells is first apparent at around midgestation (Bailey, 1987). For instance, in the rat, the first terminally differentiated (i.e. post-mitotic) neurons develop at about embryonic day 11 (Ell) (Nomes and Das, 1974). This, however, does not necessarily imply that uncommitted precursor cells are thereafter depleted from the neural anlage nor that committed precursor cells have necessarily... 

Cell commitment Lineage- commitment Uncommitment Uncommitment... 

There are two n-channel transistors on the left and two p-channel transistors on the right. There is also a ground or VSS buss line running vertically on the left and a VDD line on the right. Figure 8.75 shows the equivalent electrical schematic of the structure in Fig. 8.74. In Fig. 8.76 is shown only one pair of n- and p-channel transistors and locations within the device area where one of the customizing layers, the contacts, maybe placed. The physical representation of a particular library cell contains information of how the uncommitted transistors in the device columns should be connected. 

In obtaining experimental evidence for the precommitment hypothesis, the basic problem is to distinguish whether a cell, at the time when it is exposed to antigen, is yet uncommitted or already committed. 

The second prediction was tested by Radovich and Talmage (1967). Lethally irradiated mice received transfers of 10 or 5 X 10 normal spleen cells on the same day as transfer, horse red cells were also injected and sheep red cells were given four days later. The results of the experiment showed, that contrary to what would be expected if the cells were uncommitted, the competition was more pronounced at the higher cell concentration. 

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