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Human body tissues: Epithelial tissues The epithelial tissues are formed by cells that cover the organ surfaces, such as the surface of skin, the airways, surfaces of soft organs, the reproductive tract, and the inner lining of the digestive tract.The cells comprising an epithelial layer are linked via semi- permeable, tight junctions; hence, this tissue provides a barrier between the external environment and the organ it covers.Functions of epithelial cells include diffusion, filtration, secretion, selective absorption,There are three principal shapes of epithelial cell: squamous (scaly), columnar, and cuboidal.

Human body tissues: Epithelial tissues
The epithelial tissues are formed by cells that cover the organ
surfaces, such as the surface of skin, the airways, surfaces of soft
organs, the reproductive tract, and the inner lining of the digestive
tract. The cells comprising an epithelial layer are linked via semi-
permeable, tight junctions; hence, this tissue provides a barrier
between the external environment and the organ it covers. In
addition to this protective function, epithelial tissue may also be
specialized to function in secretion, excretion and absorption.
Epithelial tissue helps to protect organs from microorganisms,
injury, and fluid loss.
There are three principal shapes of epithelial cell: squamous
(scaly), columnar, and cuboidal. These can be arranged in a
singular layer of cells as simple epithelium, either simple
squamous, simple columnar, or simple cuboidal, or in layers of
two or more cells deep as stratified (layered), or compound, either
squamous, columnar or cuboidal. In some tissues, a layer of
columnar cells may appear to be stratified due to the placement
of the nuclei. This sort of tissue is called pseudostratified. All
glands are made up of epithelial cells. Functions of epithelial cells
include diffusion, filtration, secretion, selective absorption,