Epithelium Squamous

Flat epithelium (E. pl.) is a type of multicellular epithelium that lines the surfaces of internal organs and their derivatives.

The shape and size of cells are not constant. Protoplasm and cytoplasmic organelles are elongated into the luminal surface, rigid, stellate, the nucleus is immersed in the cytoplasm or adjacent to it, some cells have centrioles. Located pp. between the heminex and mesoderm, from where it reaches the gonads (assumed). It is formed from the endoderm, and the coelomia is still absent. At first, many cells are formed, but then they form a syncytium, from which cells (with tegument) later differentiate and divide by mitosis. The next stage of development is associated with the formation of derivative cells, from which the flat epithelial layer is formed. For example, the ectoderm is formed from the ectoboson segment in the mesophores and forms two layers: the first outer one, already consisting of cylindrical cells, the second inner one - from flat ones, surrounded by neurolemma.

This epithelium covers the internal organs: bronchi, esophagus, stomach, intestines and glandular organs, and the reproductive system. In primitive animals it is located in the coelom or body cavity.