Vibrational Spectroscopic Imaging of Soft Tissue

Infrared and Raman Spectroscopic Imaging, Second Edition. Edited by Reiner Salzer, Heinz W. Siesler. 

Epithelium is the biological and medical collective term for cover and glandular tissues. It is composed of layers of cells that line the outside and the inside surfaces of organs. The outermost layer of the skin is composed of stratified squamous epithelial cells. Other epithelial cells line the inner layers of the respiratory. 

The superficial layer is used to classify the stratification into simple, which consists of a single layer of cells, and stratified, which consists of more than one layer of cells. Stratified epithelium is usually composed of three layers. Cell division takes place in the basal cell layer (layer 1). Cells migrate and differentiate in the intermediate cell layer (layer 2) until they reach the superficial cell layer (layer 3). Specializations include keratinized and ciliated cells. Keratinized epithelium, which contains the cytoskeletal protein keratin and provides a tough impermeable barrier, occurs mainly in the skin. Ciliated cells have apical plasma membrane extensions composed of microtubules capable of beating rhythmically to move mucus or other substances through a duct. Cfiia are common in the respiratory system. 

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