In everyday speech a piece of tissue is a thin sheet of paper, used to wrap a present or, in a slightly different form, to blow the nose, or to be used in the toilet. In biology the word tissue refers to living material made up of cells or groups of cells of similar type or types. We may speak, for example, of nerve tissue or of fatty tissue, of glandular tissue or of connective tissueThe various organs of the body are made up of different types of tissue, according to the function that the organ fulfils. Brain, bone, muscle, skin, lung and liver tissue all appear very different under the microscope but they all contain variable amounts of connective tissue, essentially holding the remaining tissue in place. Structures such as tendons and ligaments, which have a purely “holding together” function are made up almost entirely of connective tissue. Collagen and elastin are the principal forms of connective tissue.. Individual organs of the body, such as the brain, the heart, the liver or the kidneys, are made up of several tissue types, almost always including connective tissueThe various organs of the body are made up of different types of tissue, according to the function that the organ fulfils. Brain, bone, muscle, skin, lung and liver tissue all appear very different under the microscope but they all contain variable amounts of connective tissue, essentially holding the remaining tissue in place. Structures such as tendons and ligaments, which have a purely “holding together” function are made up almost entirely of connective tissue. Collagen and elastin are the principal forms of connective tissue..