Differentiation of cells

The specific role of vitamin A in tissue differentiation has been an active area of research. The current thinking, developed in 1979, involves initial dehvery of retinol by holo-B >V (retinol-binding protein) to the cell cytosol (66). Retinol is then ultimately oxidized to retinoic acid and binds to a specific cellular retinoid-binding protein and is transported to the nucleus. Retinoic acid is then transferred to a nuclear retinoic acid receptor (RAR), which enhances the expression of a specific region of the genome. Transcription occurs and new proteins appear during the retinoic acid-induced differentiation of cells (56). 

The differentiation of cells occurs concomitantly to modifications of wall components. The nature of the pectins of the walls changes under the action of enzymes, among which esterases, secreted between the apical meristematic cells and the more basal differentiated cells. The apposition of new layers of pectins with different compositions at the inner surface of the walls is another mechanism by which the cells adapt their immediate environment. Using the 2F4 antibody, we have observed, in plant suspensions as well as in tissues, a third mechanism involved in wall modification. Numerous invaginations of the... 

The developmental processes which produce the AOS parallel to those of the MOS and, although they become separate systems as soon as the organisation of the forebrain begins, do not differ except in the details specific to each system. The differentiation of cell types within the organ, synapse formation in the AOB and the establishment of more central tertiary connections occur in a similar but not identical sequence. In general, the differences amount to alterations in the timing of ontogenetic events, with primary olfaction usually in advance of the... 

Late-acting HGFs, like CSF-1 or EPO, are sufficient for the proliferation and differentiation of cells that are committed to the lineage they regulate and which selectively express their receptors. However, immature multipotent hematopoietic cells have been shown to coexpress different lineage-specific as well as... 

After fertilization, the cells divide, giving rise to a blastocyst. During this time, there is little morphological differentiation of cells, except that some are located on the surfaces and others internally. The development of the blastocyst gives an internal cavity (the blastocoele) and hence further surfaces and positional differences. However, there are few specific teratogenic effects, which occur at this time, the major effects being death or overall developmental retardation. 

Retinoid Hormones Retinoids are potent hormones that regulate the growth, survival, and differentiation of cells via nuclear retinoid receptors. The prohormone retinol is synthesized from vitamin A, primarily in liver (see Fig. 10-21), and many tissues convert retinol to the hormone retinoic acid (RA). 

This study reports on the potentiality of applying a membrane biohybrid system in the field of tissue engineering and regenerative medicine evidencing the crucial points in the in-vitro reconstruction of the physiological tissue model. A number of issues need to be addressed the morphological and physicochemical properties of the membrane, the optimal density of immobilized cells, the interaction of cells with the membrane, the differentiation of cells as well as the maintenance of viability and... 

Cell studies on scaffolds of nano- and submicrometer-scaled fibers have shown that these dimensions promote not only cell adhesion, but also have beneficial effects on proliferation and differentiation of cells [174-177], These effects are more prominent with decreasing fiber diameters. It seems relevant that the cells can be guided and bridged by the artificial fibers. Meshes with aligned fibers are particularly promising, e.g., for guiding the growth of nerve cells (Fig. 8) [178],... 

M. Simlonesai, N. Sinuonescu, and G. E Fabric. Segmental differentiations of cell... 

Vitamin A (retinol) improves the humoral and cellular tolerance of a person who suffers from an infection. By affecting the differentiation of cells and regulating the metabolism of steroids, vitamin A stimulates the activity of macrophages and T-cytotoxic lymphocytes. It also raises secretion of cytokines and production of antibodies (Hughes 1999, Pfahl and Chytil 1996). 

GH, together with other hormones, can induce differentiation of cells of the 3T3 mouse fibroblast line into adipocytes in vitro [98,99]. The change involves morphological alterations, enzymic differentiation, increased hormone responsiveness, triglyceride accumulation and a limited mitogenic response. Somatomedin C has no effect on this transformation. 

Epidermal growth factor1 (EGF) EGF Promote differentiation of cells that line the gut... 

This triggers differentiation of cells in the bone marrow to produce erythrocytes. 

Oxoretinol induces differentiation of cells in culture (Achkar et td., 1996). In the developing Xenopus embryo, 4-oxoretinaldehyde is the major retinoid, acting tis a precursor of both 4-oxoretinol and 4-oxoretinoic acid, both of which activate the RAR (Blumberg et al., 1996). This developmented role of... 

The Development of Multieellular Organisms Requires the Orehestrated Differentiation of Cells... 

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