histology esophagus to large intestine

8/6/2019 Histology Esophagus to Large Intestine

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Features of normal esophageal biopsy:

- Lining epithelium is stratified squamous non-keratinizing epithelium

- Basal layer ( polygonal or cuboidal cells) is one to four cell thick and account for 15% of itsthickness. It is thickest at distal 2 - 3 cm of squamous mucosa adjacent to Z-line.

- Z -line is the squamocolumnar junction which is histologically irregular. The glandularepithelium lying higher than squamous mucosa. The lower esophageal sphincteris located in this area.

Immunohistochemical markers for Barrett's esophagus and associations to esophageal Z-lineappearance.Scand J Gastroenterol. 2001 Sep;36(9):910-5.

- Melanocytes and neuroendocrine cells may be found in the basal layer.

- The lamina propria consists of loose connective tissue. Mucous glands (esophageal cardiacglands) are present in the distal part of the esophagus.

- Vascular connective tissue papillae can indent the lamina propria as far as 2/3rd intomucosal thickness.

- Muscular mucosae is thicker in the esophagus than in any other part of the gut.

- At the esophagogastric junction gastric type glands are branched and divided into groupsby smoothmuscle fibres. Most of the cells are mucus secreting . Glands near theesophagogastric junction also contain parietal cells, chief cells and endocrine cells.

- Submucosal mucous glands are present throughout its length.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11521979&dopt=Abstract








LOCATION-Left upper quandrant-Inferior to the diaphragm-Upper portion is posterior to the liver-May descent to the pelvis

Anatomically divided into 4 regions:

-Cardiac region: Surrounded by esophageal sphincter .- Fundus: Lies against the diaphragm.

- Body (corpus):- Pylorus (pyloric antrum): Ends at the pyloric sphincter which is a thickening of themuscle walls.

Types of cells present in the stomach:

Mucous secreting cells (goblet cells)-Line the luminal surface of the stomach and gastric pits and gastric glands. Produce mucusand bicarbonate.

Mucous neck cells-Present in the neck of the gland. Produce mucin.

Parietal cells (oxyntic cells)- Distributed throughout the length of the gland , but

numerous in the middle portion. Large, rounded cells with eosinophilic cytoplasm andcentrally located nucleus. Produce gastric acid.

Chief cells (peptic or zymogenic cells)-Clustered at the base of the gland. Identified by basally located nuclei and strongly basophilicgranular cytoplasm.Produce pepsinogen, digests protein.



Normal Histological Features:

The gastric mucosa consists of surface epithelium, gastric pits and gastric glands.

The gastric glands extend from the muscular mucosae to extend into the stomach lumen viagastric pits.

The foveolar cells lining the surface and gastric pits are identical throughout the stomachGlands differ in different regions of the stomach.Gastric pits occupy approximately 25% of the mucosa. Pits lie parallel to one another. Theseare separated by the lamina propria. There is more lamina propria separating the pits thanbetween the glands.

In normal gastric biopsy degree of pit and glandular separation should be same throughoutthe biopsy.

Cardia-Small area of predominantly mucus secreting glands surrounding the entrance of theesophagus. Glands are less coiled than in the antral glands.The pits are shorter than theantropyloric pits.

Fundus and body-Major histological region. Consists of straight, tubular glands. Strands of muscularis mucosaeextend between the glands from the base. The glands secrete gastric juices as well asprotective mucus.

Pylorus-Branched glands open into deep irregular shaped pits. Composed of mucus secreting cells.Mucus secreted by pyloric glands lubricate and protect entrance to the duodenum.Scattered 'G' cells (endocrine cells), secrete gastrin.

Note:

Gastric mucosa forms a barrier to diffusion of gastric acid from the gastric lumen.Damage of gastric mucosa > back diffusion of luminal acid > tissue acidosis > vascularcompromise>mucosal congestion and necrosis.

Damaged gastric mucosa> regenerates from generating zone (mucous neck region)1. Cells pass upwards to differentiate into foveolar cells2. Cells pass downwards to differentiate into glandular cells.



The small intestine consists of duodenum, jejunum and ileum and is the principal

site of absorption of food products from gastrointestinal tract. (Total length in man= 4 to 6m)

The epithelial component of the small bowel is composed of villi (finger like projections) andcrypts (crypts of Liberkuhn).

Normal villous to crypt length length ratio is approximately 3:1 to 5:1.When 4 normal villi are identified in a specimen, it usually indicates that the entire specimenhas a normal villous architecture (although presence of focal lesion can not be completelyruled out).Due to high rate of cell turnover numerous mitotic figures are noted in the crypts.

Cells in the villi and crypts: The villous epithelium is composed of columnar absorptive cells (Enterocytes) & mucinsecreting cells (Goblet cells).

The enterocytes are characterized by basally located nuclei which are evenly aligned.PAS positive brush border is present on the luminal surface of enterocytes.Goblet cells are scattered among the enterocytes. Goblet cells contain Alcian blue positivesialomucin.

The third cell type are the Paneth cells, present in the crypts. These are characterised bybrightly eosinophilic, supranuclear, cytoplasmic granules.Endocrine cells are present in the crypts as single cells or in clusters. Unlike paneth cellsthese are present in the basal part of the cells (infranuclear position).

Inflammatory cells: These are present in the lamina propria and usually consists of plasma cells andlymphocytes. Intraepithelial lymphocytes occur in the ratio of 20 lymphocytes per 100enterocytes (1 lymphocyte per 5 enterocytes).IELs are T-lymphocytes and express CD3, CD5 & CD8. CD4 is not expressed.

Duodenum: The villi are shorter and broader than jejunal villi, with branching extensions.Brunner's glands are lobular collections of mucin secreting glands that empty into cryptsthrough ducts. Brunner's glands contain neutral PAS positive mucin.Brunner's glands are abundant in the first part of duodenum, less prominent in second partand not present in the third and fourth parts.In duodenum there is gradual transition of the epithelium across the gastroduodenal

junction.Antral-type gastric epithelium extends into the proximal duodenum (upto 6mm).In proximal duodenum the villi are lines by cells showing features of both antral andintestinal mucosa.More numbers of mononuclear cells are normally present in the duodenum than rest of thesmall intestine.

Ileum:Increased number of goblet cells.Villi are shorter more finger-like in shape.Lymphoid nodules (Peyer's patches) are prominent in the ileum.



Histological features in a Normal Large Intestinal Biopsy:

MUCOSAL ARCHITECTURE:

There is increase in thickness of the mucosa from the caecum (500 micrometer) to therectum (1000 micrometer).

Crypts are aligned parallel to the crypt bases. Crypts are straight and narrow and mostlyunbranched separated by a thin rim of lamina propria. The distance between the crypts andthe internal diameter of the crypts are constant.

Slight variation in crypt architecture, intercryptal spacing and occasional crypt branchingmay occur in normal biopsies.

Crypts are deeper in the rectum and sigmoid colon than in the proximal part of the colon.

SURFACE EPITHELIUM:

Composed of absorptive (tall columnar), goblet and endocrine cells.

Ratio of the number of tall columnar cells to goblet cells is 4:1.

Paneth cells are usually present in the caecum & proximal colon (usually confined to thecrypt bases).

Presence of Paneth cells more distally indicates metaplastic change seen in chronicinfection.

The proliferative zone in the base of the crypt is composed of low cuboidal stem cells.

Surface epithelial cells overlying lymphoid follicles are more cuboidal and compactlyarranged rather than columnar cells elsewhere (this should not be mistaken for dysplasticcells in ulcerative colitis).

LAMINA PROPRIA:

Loose, areolar connective tissue which appears highly cellular due to the presence of chronicinflammatory cells in the superficial part of the lamina propria.

Predominantly plasma cells are present together with scattered lymphocytes (mostly T-cells).

Inflammatory cells in the deeper part and separation of crypt bases from muscularismucosae by a band of plasma cells and lymphocytes is indicative of chronic inflammatorybowel disease.

Occasional neutrophils are present in the lamina propria of normal colonic biopsies.



Neutrophils in the surface and crypt epithelium is indicative of a pathological process.

Lymphoid follicles of B-lymphocytes are present in colonic mucosa and may extend throughmuscularis mucosae into submucosa.

At these points mucosal crypts extend into the mucosa forming lymphoid-glandular

complexes (should not be mistaken for a pathological process).

MUSCULARIS MUCOSAE:

Thin smooth muscle layer (inner circular and outer longitudinal layer).

SUBMUCOSA:

There is loose connective tissue with collagen and elastic fibres. Meissner's plexus of autonomic nerve fibres with ganglion cells are present. Detailed examination of this layer isnecessary in Hirschsprung's disease.

histology esophagus to large intestine

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