bench definition, bench meaning | English dictionary. bench. n an apparatus for experimentation in optics, typically consisting of an adjustable arrangement of light source, lenses, prisms, etc. bench.
3 Principal characteristics of cells that make up epithelium. -Cells are closely apposed-they adhere to one another via specialized cell junctions-Exhibit both structural and functional polarity-Epithelium creates a selective barrier between the external environment and the underlying connective tissue.î î î.Cells are closely apposed-they adhere to one another via specialized cell junctions-Exhibit both structural and functional polarity-Epithelium creates a selective barrier between the external environment and the underlying connective tissue. î î î.
The most distinctive xylem cells are the long tracheary elements that transport water. Tracheids and vessel elements are distinguished by their shape; vessel elements are shorter, and are connected together into long tubes that are called vessels.Xylem also contains two other cell types: parenchyma and fibers.Xylem can be found: 1  in vascular bundles, present in non-woody plants and non-woody parts of woody plants. 2  in secondary xylem, laid down by a meristem called the vascular cambium in woody plants.n most plants, pitted tracheids function as the primary transport cells. The other type of tracheary element, besides the tracheid, is the vessel element. Vessel elements are joined by perforations into vessels. In vessels, water travels by bulk flow, as in a pipe, rather than by diffusion through cell membranes.