An introduction to the XML Document Type Definition. What XML building blocks are defined in a DTD. How to define the elements of an XML document using DTD. How to define the legal attributes of XML elements using DTD. How to define XML entities using DTD. How to test for DTD errors while loading XML documents. Some DTD examples.
19 Jul, 2012 what is 0. The Basement membrane is a layer of fiber that is located under epithelium or endothelium. The epithelium is the tissue that lines the surfaces and cavities of organs, whereas the endothelium lines the inside of blood vessels.
In animals the plasma membrane is the outermost covering of the cell whereas in plants, fungi, and some bacteria it is located beneath the [[cell wall]. Although some cells form another layer above the cell membrane (called cell wall), other cells have the cell membrane as the only protective barrier between the cytoplasm and the outside of the cell. The cell membrane is a phospholipid bilayer interspersed with proteins as depicted in the fluid mosaic model. Its structure and composition makes it selectively permeable (or semipermeable), which means not every substance is allowed to enter or leave the cell.