Squamous epithelial tissue

Skala MC, Squirrell JM, Vrotsos KM, Eickhoff VC, Gendron-Fitzpatrick A, Eliceiri KW, Ramanujam N (2005) Multiphoton microscopy of endogenous fluorescence differentiates normal, precancerous, and cancerous squamous epithelial tissues. Cancer Res 65 1180—1186... 

The asymmetric unit membrane that is unique to the umbrella cells of urinary tract transitional epithelium contains a transmembrane protein that is unique to uro-thelium. In studies performed thus far, the uroplakins are highly specific for transitional epithelium, with moderate sensitivityand are not seen in squamous epithelial tissue. 

Stratified squamous epithelial tissue is a frequently found epithelium in the human body (nasopharyngeal and oral cavities, esophagus, urethra, vagina, cervix, and others). It is a multilayered structure consisting of a layer of actively dividing basal cells anchored to the basement membrane, beneath which one finds connective tissue (stroma). The daughter cells created by the division of the basal cells form the parabasal layer and mature and migrate to the surface layer. 

The presence of human papilloma virus (HPV) is associated with female genital tract diseases such as condyloma, Bowenoid papulosis, and cervical, vaginal, and vulvar intraepithelial neoplasia and carcinoma. A general concern is the association of HPV with cervical cancer (Gl). The HPV consists of an icosahedral viral particle (virion) containing 8000 base pairs, a circular, double-stranded piece of DNA surrounded by a protein capsid. Viral replication takes place within the nuclei of infected squamous epithelial cells (H5). Following infection of epithelial cells, the viral DNA penetrates throughout the entire thickness of the epithelium, but intact viruses are found only in the upper layers of tissue. 

Li C, Zhan X, Li M, Wu X, Li F, Li J, et al. Proteomic comparison of two-dimensional gel electrophoresis profiles from human lung squamous carcinoma and normal bronchial epithelial tissues. Genomics Proteomics Bioinformatics 2003 l(l) 58-67. 

A chronic inhalation MRL of 0.008 ppm was derived based on a minimal LOAEL of 0.24 ppm for histological evidence of mild damage to the nasal epithelial tissue (squamous metaplasia, loss of ciliated cells, goblet cell hyperplasia, and mild dysplasia in biopsied tissue) in formaldehyde exposed chemical workers (Holmstrom et al. 1989c). To derive the MRL, the minimal LOAEL was divided by an uncertainty factor of 30 (3 for the use of a minimal LOAEL and 10 for human variability). 

The epithelium (the biological and medical collective term for covering and glandular tissues) is composed of layers of cells that line the outside and inside surfaces of organs. The outermost layer of the skin is composed of stratified squamous epithelial cells, while other epithelial cells line the insides of the respiratory, gastrointestinal, reproductive and urinary tracts, and also comprise the exocrine and endocrine glands. The functions of epithelial cells include secretion, absorption, protection, transcellular transport, sensation detection and selective permeability. The endotheUum-the irmer lining of blood and lymph vessels-is a specialized form of epithelium. 

On contact with a mucosal surface lined by colimmar, cuboidal, or noncornifled squamous epithelial cells, the gonococci attach to cell membranes by means of surface pUi and are then pinocytosed. The virulence of the organism is mediated primarily by the presence of pili and other outer membrane proteins. After mucosal damage is established, polymorphonuclear leukocytes (PMNs) invade the tissue, submucosal abscesses form, and purulent exudates are secreted. "... 

Another member of the p53 family is p63, which is signihcant in the development of epithelial tissue and squamous cell carcinomas. p63 expression was evaluated in 408 cases of lung cancer by tissue microarray in two different laboratories by Au and associates. Table... 

Figure 5.30 Illustration of the structure of epithelial tissue barriers in the body. Modified from [31] and Stedmann s Medical Dictionary. Epithelial tissues have a variety of histological patterns (a) simple squamous as found in the initial segments of ducts in glands and the alveolus (b) simple cuboidal as found in glandular ducts and ovary (c) simple columnar as found in stomach, intestines, uterus, and cervix ...

Wall of the cyst is composed of a squamous epithelial lining supported by a collagenous basal membrane solid masses are made of cords of epithelial cells with a central core of richly vascularized connective tissue Evolution ... 

The skin is composed of two distinct but intimately associated layers of tissues, namely the epidermis and dermis (Fig. 1). The epidermis is further divided into the viable epidermis (a layer of stratified squamous epithelial cells in various stages of differentiation) and the stratum comeum (a layer of dead cells that form the outer layer of skin). In contrast to most tissues, the epidermis is in a state of flux. The cells at the surface of the skin are replaced continuously by cells migrating up from the lower levels of the skin in a process known by several names, including keratinization, comification, or differentiation. 

Mitotic effect. STE, administered to the buccal mucosa of 15 female HMT rats, 6 months of age, weekly for 1 year, produced hyperorthokeratosis, acanthosis, numerous binucleate spinous cells, and subepithelial connective tissue hyalinization. Verrucous carcinoma and squamous cell carcinoma were not seen. Karyotyping revealed that lymphocytes of tobacco-treated, as well as control rats, had normal chromosome number and morphology. However, approx 25% of buccal epithelial cells of the tobacco-treated rats were tetraploid and 5% octa-ploid, compared with only 11% tetraploid and no octaploid in the controls. Results indicated that the mitotic process could be disturbed by tobacco treatment b Molluscicidal activity. Water extract of the dried leaf, at a concentration of 168 ppm, produced equivocal effect on Lymnaea luteola . 

Male and female Fischer 344 rats and B6C3Fj mice were exposed to 3, 15 or 75 ppm [23, 115 or 577 mg/m J ethylene dibromide for 6 h per day on five days per week for 13 weeks. Rats and mice examined after 13 weeks of exposure showed severe necrosis and atrophy of the olfactory epithelium in the nasal cavity after inhalation of 75 ppm ethylene dibromide. Lower concentrations induced squamous-cell metaplasia, hyperplasia and cytomegaly of the epithelium of the respiratory nasal turbinates. Metaplasia, hyperplasia and epithelial cytomegaly were also seen in other respiratory tissues (larynx, trachea, bronchi, bronchioles) at this dose (Reznik et al., 1980). 

In vitamin A deficiency the internal epithelial surfaces of lungs and other tissues, which are usually rich in mucous secreting cells and in ciliated cells, develop thick layers of keratinizing squamous cells similar to those on the external surface of the body. 

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