The esophagus provides passage between the oral cavity to the stomach. Compared to other regions of the GI tract, the esophagus is a fairly simple tube. Functional specializations are correspondingly few.The non-keratinized stratified squamous epithelium is present in
The esophageal lining is protected by a stratified squamous epithelium. Because this epithelium is normally not exposed to dryness or to abrasion, it is non-keratinized. Scattered submucosal mucous glands provide lubrication. A well-developed muscularis provides peristaltic propulsion of food. Even when upside down, the esophagus can push food and drink to the stomach.
The basic layers of the GI tract are especially distinct in the esophagus. Esophageal epithelium is non-keratinized stratified squamous. Note that the basal surface of the epithelium can be deeply indented by connective tissue papillae.
In oblique section through the epithelium, the connective tissue papillae can look like "islands", apparently surrounded by epithelium. Beginning students frequently mistake these for glandular structures.
Epithelial continuity is critical for normal function. A breach in the epithelium creates an ulcer. Esophageal epithelium may be transformed to a simple columnar form in the condition called Barrett's esophagus. The epithelium is variously described as resembling that of gastric mucosa i. The cause of this condition remains uncertain, but it may represent a metaplastic response to chronic inflammation caused, e.
At the junction with the stomachthe stratified squamous epithelium of the esophagus makes an abrupt transition to the simple columnar epithelium of the gastric mucosa. Esophageal lamina propria is less cellular fewer lymphocytes than that in the stomach and intestine, presumably because the protective stratified squamous epithelium is more effective at keeping out foreign antigens.Laqab ki jama in urdu
Lymph nodules are uncommon in the esophagus, but they may occur here as elsewhere along the GI tract. Esophageal muscularis mucosa is noticably thicker than that in the stomach and intestine, and includes only longitudinal muscle fibers.
Because the longitudinal fibers occur in bundles, a longitudinal section passing between bundles may not include any evidence of muscularis mucosae. Connective tissue of the esophageal submucosa is typically more fibrous and less cellular than that the lamina propria of the mucosa.Skip to content. Access to the supplemental resources for this session is password-protected and restricted to University of Michigan students. If you are a University of Michigan student enrolled in a histology course at the University of Michigan, please click on the following link and use your Kerberos-password for access to download lecture handouts and the other resources.
The oral cavity is lined by a mucous membrane the oral mucosa consisting of a stratified squamous epithelium, which may or may not be keratinized, and an underlying connective tissue layer, the lamina propria. The surface is kept moist with mucus produced by the major and numerous minor salivary glands.
The oral mucosa is well supplied with nerve endings and, on the dorsal surface of the tongue, special sensory endings for taste. The submucosa underlying the lamina propria of the oral cavity is variable.
At times the lamina propria and submucosa are substantively so similar that they merge imperceptibly. In your slides, the submucosa will be distinguished from the lamina propria only by the presence of minor salivary glands in a loose textured tissue, and we do not ask you to recognize this distinction microscopically.
A stratified squamous non-keratinized epithelium lines the oral surface of the lips, cheeks, floor of mouth, and covers the ventral surface of the tongue In slide human and M monkey of the lip, note that skin stratified, keratinized squamous epithelium with hair follicles covers the external surface View Imageskeletal muscle orbicularis oris muscle forms the core View Imageand a mucosal epithelium stratified, non-keratinizing squamous epithelium covers the internal surface View Image.
A lamina propria underlies the mucosa and small salivary glands labial salivary glands View Image are present in the submucosa. Note the transition zone between the keratinized epithelium of the skin and the nonkeratinized epithelium of the mucosa. In the transition zone, long connective tissue papillae extend deep into the epithelium.
Capillaries are carried close to the surface in these papillae. Because the epithelium is very thin in this region, the lips appear red this arrangement may or may not be apparent in your glass slides. Salivary glands are lacking in the vermillion zonetherefore, the lips must be continuously moistened by the tongue to prevent drying out.
A stratified squamous keratinized epithelium is found on surfaces subject to the abrasion that occurs with mastication, e. Slidewhich you used to study bone and the respiratory system, is a longitudinal section through the palate and includes the lip, gingiva, hard palate, and a portion of the soft palate [orientation]. This tissue is from a term fetus with unerrupted teeth and the epithelium over the hard palate is not yet fully differentiated i.
The slide is, however, a good overall orientation to the histology of the hard and soft palate. In the adult the epithelium of the hard palate is keratinized.Stratum basale is a single layer of cuboidal to columnar cell rest on a wavy basement membrane.
Locations: oral cavity, pharynx, esophagus, anal canal, and vagina. Such sites are normally subjected to moderate mechanical abrasion and are kept moist by local glandular secretions. It consists of two or more layers of cells, with only the superficial cells having a cuboidal shape.
It is frequently occurs as two-layered epithelium located in the large glandular ducts. It consists of several layers of cells with only the superficial layer having tall columnar cells. Locations: distal portion of the urethra, parotid and mandibular ducts, lacrimal sac and lacrimal duct. It is a form of stratified epithelium found only in the urinary tract lines the ureter and urinary bladder.
It is highly specialized to resist a great degree of stretch and to withstand the toxicity of urine. In relaxed state empty bladder it is consists of layers of cells, the basal layer is cuboidal in shape rests on thin basal lamina. The intermediate layer consists of several layers of polyhedral or pear-shaped cells. The surface cells are large cuboidal or dome-shaped with convex outer surface and concave inner surface.
Their nuclei are large, spherical with prominent nucleoli, some cells are binucleated. In stretched state full bladder it appears only as two or three cell layers thickness. The intermediate and surface layers are extremely flattened. The superficial cells have a thicker plasmalemma that acts as a barrier against diffusion of fluid from the subepithelial tissue to the hypertonic urine.
Stratified epithelium Epithelial Classification simple Stratified modifications glands special types. Figure 1 Figure 2 Figure 3 Figure 4. Copyright Prof.This section is rather thick and over-stained with eosin but does show some interesting features. First find the surface epithelium. If you start at the part with hair follicles you will encounter a point of transition from the keratinized stratified squamous epithelium of the skin outside of the lip to the nonkeratinized stratified squamous epithelium of the lip oral mucosa.
This is an example of a mucocutaneous junction. Where else in the body do you find such junctions? This transition in the lip is seen grossly as the vermillion border. This is a common site for carcinoma of the lip, particularly in heavy smokers. This is a very low power view through a section of the lip which includes the mucocutaneous junction that occurs where the typical skin epithelium of the outer lip is replaced with the epithelium of the oral mucosa.
This image also demonstrates the extent of skeletal muscle within the lip and the presence of labial salivary glands. This is a low power view of the outer portion of the lip, demonstrating the characteristic keratinized, stratified squamous epithelium, associated hair follicles and sebaceous glands. This is a medium power view at the mucocutaneous junction where the keratinized, stratified squamous epithelium of the outer lip on the right gives rise to the non-keratinized, stratified squamous epithelium of the oral mucosa on the left.
This is a medium power view of the lip on the orad side of the mucocutaneous junction.Tu sabias que decia te quiero
Note the thick, non-keratinized stratified squamous epithelium and the abundance of blood vessels within the underlying connective tissue seen to better effect in the next image. Clusters of labial salivary glands are also apparent. A high power view of the junction between epithelium and underlying connective tissue in the oral portion of the lip illustrates the extensive blood supply of this area, a feature which accounts for the reddish hue of this vermilion border of the lip.Squamous metaplasia is a benign non-cancerous change metaplasia of surfacing lining cells epithelium to a squamous morphology.
Common sites for squamous metaplasia include the bladder and cervix. Smokers often exhibit squamous metaplasia in the linings of their airways. These changes don't signify a specific disease, but rather usually represent the body's response to stress or irritation. Vitamin A deficiency or overdose can also lead to squamous metaplasia. In regard to the cervix, squamous metaplasia can sometimes be found in the endocervixas it is composed of simple columnar epitheliumwhereas the ectocervix is composed of stratified squamous non-keratinized epithelium.
Squamous metaplasia may be seen in the context of benign lesions e. From Wikipedia, the free encyclopedia. Nutrition and Cancer. Saunders Elsevier. Surgical pathology Cytopathology Autopsy Molecular pathology Forensic pathology Oral and maxillofacial pathology Gross examination Histopathology Immunohistochemistry Electron microscopy Immunofluorescence Fluorescence in situ hybridization.Tricare copay for urgent care
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Wikimedia Commons. This article related to pathology is a stub. You can help Wikipedia by expanding it.The cervix is a site with special clinical significance, since it is both susceptible to cancer and also relatively accessible for routine diagnostic examination.
The cervix is also prone to inflammation ; see WebPath for an illustrative example. The cervix includes the opening os from the uterus into the vagina. The tissues associated with this opening are capable of extreme stretching during childbirth.
In the vicinity of the os is a transition from the simple columnar, endometrial -type epithelium of the endo cervix to the stratified squamous nonkeratinized epithelium of the ecto cervix, which is continous with that of the vagina.
Oral Cavity, Salivary Gland, Pharynx, Esophagus, and Stomach and Quiz 4
The endocervical mucosa contains many epithelial crevices which confer a glandular appearance. Before puberty, the epithelial transition occurs near the os. However, enlargement of the uterus and cervix during puberty cause the endocervical mucosa to evert, resulting in a transitional zone of columnar epithelium on the outer surface of the cervix, called the ectropion.
Squamous metaplasia eventually converts this zone into stratified squamous epithelium, but in the process some invaginations of columnar epithelium may lose their connection to the surface.
Continuing secretion at such sites results in the formation of small Nabothian cysts. The epithelial changes which occur around the cervical os seem to predispose this site to malignant transformation.
For examples of cervical dysplasia, see WebPath and WebPath. The cervical stroma is largely fibrous, with a high proportion of elastic fibers, interwoven with smooth muscle.
The stroma is also highly vascularized and richly innervated. The vagina is lined by non-keratinized stratified squamous epithelium.
The epithelial cells accumulate glycogen as they approach the surface. S upporting fibromuscular tissue is highly vascular and richly innervated, with no clear differentiation of mucosa and submucosa unlike esophaguswhich has a superficially similar epithelium. Trichrome stain facilitates observation of smooth muscle. The vulvar vestibule between labia majora and labia minora is lined by stratified squamous epithelium, non-keratized to thinly keratinized.
Opening into the vestibule are Bartholin's glands lined by columnar mucus-secreting cells and highly variable Skene's glands analogous to the male prostate. ERG Index.A pseudostratified epithelium is a type of epithelium that, though comprising only a single layer of cellshas its cell nuclei positioned in a manner suggestive of stratified epithelia.
As it rarely occurs as squamous or cuboidal epitheliait is usually considered synonymous with the term pseudostratified columnar epithelium. The term pseudostratified is derived from the appearance of this epithelium in section which conveys the erroneous pseudo means almost or approaching impression that there is more than one layer of cells, when in fact this is a true simple epithelium since all the cells rest on the basement membrane.Dessert table ideas for birthday
The nuclei of these cells, however, are disposed at different levels, thus creating the illusion of cellular stratification. Not all ciliated cells extend to the luminal surface; such cells are capable of cell division providing replacements for cells lost or damaged. Pseudostratified epithelia function in secretion or absorption. If a specimen looks stratified but has ciliathen it is a pseudostratified ciliated epithelium, since stratified epithelia do not have cilia.
From Wikipedia, the free encyclopedia. Tissue type. This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. Anatomical Record. Pathologic Basis of Disease. Epithelial tissue. Squamous Cuboidal Columnar.
Simple squamous epithelium Endothelium Mesothelium Simple cuboidal epithelium Simple columnar epithelium Pseudostratified columnar epithelium Respiratory epithelium Stratified squamous epithelium Stratified cuboidal epithelium Stratified columnar epithelium Transitional epithelium Urothelium. Tubular gland Alveolar gland. Serous glands Mucous glands. Authority control TH : H2. Categories : Epithelial cells. Hidden categories: CS1 maint: multiple names: authors list Articles with short description Short description matches Wikidata Articles needing additional references from January All articles needing additional references All accuracy disputes Articles with disputed statements from November Wikipedia articles with TH identifiers.
Namespaces Article Talk. Views Read Edit View history. Help Learn to edit Community portal Recent changes Upload file. Download as PDF Printable version. Wikimedia Commons. Illustration depicting Pseudostratified Ciliated Columnar Epithelium. Anatomical terms of microanatomy [ edit on Wikidata ].
Difference Between Keratinized and Nonkeratinized Epithelium
Simple Stratified. Simple Stratified Pseudostratified. Table of epithelia of human organs. TH : H2.
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