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Animal tissues
Animal tissues can be grouped into four basic types. Multiple tissue types comprise organs and body structures. While all animals can generally be considered to contain the fourtissue types, the manifestation of these tissues can differ depending on the type of organism. For example, the origin of the cells comprising a particular tissue type may differ developmentally fordifferent classifications of animals. The epithelium in all animals is derived from the ectoderm and endoderm with a small contribution from the mesoderm which forms the endothelium. By contrast, a trueconnective tissue is present only in a single layer of cells held together via occluding junctions called tight junctions, to create a selectively permeable barrier. This tissue covers all organismalsurfaces that come in contact with the external environment such as the skin, the airways, and the digestive tract. It serves functions of protection, secretion, and absorption, and is separated fromother tissues below by a basal lamina. Endothelium, which comprises the vasculature, is a specialized type of epithelium.
Epithelial Tissue
This is a connective tissue in which the ground substance ormatrix is composed of elastin, which is impregnated with salts of calcium and magnesium.
Muscular Tissue
Muscles of the body are made up of elongated muscle cells also known as muscle fibre. Themovement of the body is brought about by the contraction and relaxation of contractile protein present in muscle cells.
Plant tissues
Examples of tissue in other multicellular organisms are vasculartissue in plants, such as xylem and phloem. Plant tissues are categorized broadly into three tissue systems: the epidermis, the ground tissue, and the vascular tissue. Together they are often referredto as biomass.
Meristematic Tissues (Meristems)
The main function of meristematic tissue is to continuously form a number of new cells and help in growth.
Permanent Tissues
These tissues are...
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