Tissue patterns

In the ways described above, only the genes required at a given moment are expressed. This not only helps to conserve the energy of the cell, but also is critical for correct cellular differentiation, tissue pattern formation and formation of the body plan. 

Apparently there exists in plants in general a rather clear-cut division of labor in the growth of the stem the apical meristem is the site of shoot organogenesis (leaf initiation and tissue pattern determination) but its direct contribution to stem growth is small the great majority of cells that actually constitute the mature... 

PHAs are made from renewable sources such as sugarcane, one of the most significant and traditional Brazilian feedstocks, as well as from other renewable sources such as starch, vegetable oils etc. Their applications range from packaging to disposables and applications in the medical field (matrices for slow drug release, implants, artificial tissues, patterns and suture wire) due to their biocompatibility. These hiopolymers are similar to plastics produced from petroleum and can be laminated, molded and injected easily. Also, they are fully biodegradable in a period of six months to a year. ... 

Matsumoto, T., Sasaki, J., Alsberg, E., Egusa, H., Yatani, H., Sohmura, T., 2007. Three-dimensional cell and tissue patterning in a strained fibrin gel system. PLoS One 2, el211. 

The cellular type of mechanical organization has certain limitations and is suitable mainly for static tissue situations. Animals lead active lives and their mechanical structures are adapted to various dynamic requirements, both in the stresses they have to meet and in the changes which tissues undergo in the course of a lifetime. As a result, in many animal tissues, the cells have lost their primary mechanical function and occupy a very much smaller proportion of the total volume of the tissue than in plants. In animal tissues the mechanical function is taken over by extracellular tissue elements, comprising protein fibres embedded in a polymeric aqueous gel. The restriction of mechanical function to extracellular tissue components permits larger spaces between cells and makes possible a greater freedom in tissue pattern. Thus more than one type of cell may occur in the same tissue and there is scope for continuous reorganization to meet the... 

Maeda, R., Kobayashi, A., Sekine, R., Lin, J.-J., Kung, H.-F. and Maeno, M. (1997) Xmsx-1 modified mesodermal tissue pattern along dorsoventral axis in Xenopus laevis embryo . Development, 124, 2553-60. 

For a more extensive discussion concerning the role of methylated nucleosides at the molecular level in cellular processes, we refer to more detailed reviews34,38,44,45 which have appeared in the last few years. Following different lines of research,in the last decade several data have appeared in the literature which suggest a relationship between the cell or tissue pattern of tRNA species and cell differentiation or malignant transformation. Differences in tRNA patterns have been shown in several instances for malignant tissues versus normal ones, often associated with modulation of activity of the enzymes which methylate tRNA. Also in this case we... 

The cells as they expand and differentiate become part of the continuing pattern of arrangement of the primary root tissues. It could be that the primary tissues impose their pattern upon the differentiating cells by some apically directed influence. When, however, the embryo root is initiated or when root meristems arise in tissue culture masses it is clear that the root meristem precedes the existence of mature root tissues. Further, it has been shown that if root tips are cut off, re-orientated and then replaced on the root stump, the new tissues as they appear are out of line with those of the stump. It is in the apical millimetre or so of the root, in the region of active cell division, that the tissue pattern is determined. The destiny of cells in the meristem is determined by their microenvironments in that region. 

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