Colon Histology 2009

From Embryology
Jump to: navigation, search

Introduction

AEsmall.jpg

This practical class will initially provide an overview of the microanatomy of the normal colon, and discuss the functional significance of the various histological structures. The second part, and majority of the class time, will study of the histopathology of colonic neoplasms. This current page only covers the normal colon histology.


Current 2011 Page: Gastrointestinal Tract - Colon Histology


Colon Function

  • Reabsorption of water and inorganic salts.
  • Secretion of mucus that acts as a lubricant during the transport of the intestinal contents.

Large Intestine Structure

large intestine anatomy
retroperitoneal
  • large intestine - cecum (+appendix), colon, rectum (+anal canal)
  • colon anatomically four parts - ascending, transverse, descending, and sigmoid.
  • layers from lumen outward - mucosa, submucosa, nuscularis externa, adventitia/serosa


Note: This current page contains both additional information and images to the Medicine practical class set and is provided for educational information and study purposes only.

Objectives

  • The aim of this practical class is to relate the normal histology of the colon to its function, and to contrast this with the changes that occur in colonic neoplasia.
  • The histopathology of colonic neoplasms will be correlated with common clinical features and the biological behaviour of the disease.  


Textbook

  • Junqueira, L.C., and Carneiro, J. (2005) Chapter 15. In The Respiratory System in Basic Histology, (11th ed., pp. 311-316). New York: Lange Medical Books/McGraw-Hill
  • Kumar, V., Abbas, A.K., Fausto, N. and Mitchell, R.N. (2007). Chapter 15. In Robbins' Basic Pathology (8th ed., pp. 579-586). Philadelphia, PA: Elsevier Saunders


Slides

histology terminology

UNSW Virtual Slidebox Virtual Slidebox Phase 1 | Histology and neoplasms of the colon

Identify

  1. A mucosa within which exists the epithelium, the intestinal glands (glands of Lieberkuhn), lamina propria and muscularis mucosa. Note that there are NO plicae circulares or villi in the colon but temporary folds exist instead.
  2. A submucosa
  3. A muscularis externa containing inner circular and outer longitudinal smooth muscle layers. Note that taeniae coli are not present in this section of colon (Taeniae coli represent 3 broad longitudinal bands of smooth muscle)
  4. The outermost serosa (Note that the serosa covers the transverse and sigmoid colon and are attached to the body wall by a mesentery which contains loose CT, adipocytes, blood vessels and nerves. The ascending and descending colon are retroperitoneal and the outer layer on their posterior surface is the adventitia)
  5. Lymphatic nodules in the lamina propria and submucosa
  6. A myenteric (Auerbach) nerve plexus (parasympathetic) exists between the muscularis externa layers.

Colon Histology

colon histology overview


Colon histology 001.jpg Colon histology 002.jpg


Crypts of Lieberkühn - (intestinal gland, intestinal crypt) Longitudinal | Transverse

Colon histology 004.jpg Colon histology 005.jpg Colon histology 009.jpg


Colon histology 006.jpg Colon histology 007.jpg

Links

Terms

adipocytes - fat cells.

adventitia - (tunica adventitia) outermost connective tissue layer covering the gastrointestinal tract of the ascending colon, descending colon and the rectum (retroperitoneal structures are covered in adventitia, peritoneal structures are covered in serosa). The transverse colon is peritoneal and therefore covered in a serosa.

Auerbach's plexus - (myenteric plexus) part of the enteric nervous system lying between outer longitudinal and inner circular layers of the muscularis externa. Embryologically formed from neural crest cells.

appendices epiploicae - small pouches in adventitia filled with fatty tissue.

cecum - blind pouch portion of gastrointestinal tract that forms the beginning of the large intestine.

contraction - colon has two forms of muscular contraction: segmented (local) and peristaltic (movement of contents).

Crypts of Lieberkühn - (intestinal gland, intestinal crypt) named after Johann Nathanael Lieberkühn a historic German anatomist.

external anal sphincter muscle - thick region of circular skeletal muscle located at ano-rectal junction under the skin.

FAP - (familial adenomatous polyposis)

goblet cells - simple columnar epithelial cells that secrete mucus, named by the cell's goblet-like shape.

haustra - small pouches generated by sacculation, due mainly to taenia coli shorter length.

HNPCC - (hereditary nonpolyposis colorectal cancer)

internal anal sphincter muscle - thickened region of muscularis externa circular smooth muscle located at ano-rectal junction.

intestinal gland - (Crypts of Lieberkühn, intestinal crypt)

lamina propria - (lamina propria mucosae) the layer of loose connective tissue beneath the gastrointestinal tract epithelium and with the epithelium form the mucosa.

lymphatic nodules - most abundant in the cecum and vermiform appendix, but also irregularly scattered over the rest of the colon.

Meissner's plexus - (submucosal plexus) part of the enteric nervous system lying in the submucosa layer. Embryologically formed from neural crest cells.

mucosa - the gastrointestinal tract epithelial layer, lamina propria and muscularis mucosa together form the mucosa.

muscularis externa - gastrointestinal tract outer smooth muscle layer formed generally by an inner circular and an outer longitudinal layer, in the colon the outer layer form the taenia coli.

muscularis mucosa - thin layer of smooth muscle outside the lamina propria and separating it from the submucosa of the gastrointestinal tract, this layer ends at the recto-anal junction.

myenteric plexus - (Auerbach's plexus) enteric nervous system lying between outer longitudinal and inner circular layers of the muscularis externa. Embryologically formed from neural crest cells.

retroperitoneal - (extraperitoneum) the anatomical space in the abdominal cavity behind (retro) the peritoneum space, used to describe structures, organs and tissues located in this region.

sacculation - process of pouch formation, the colon pursed out to form little pouches.

serosa - outermost connective tissue layer covering the gastrointestinal tract in regions where it passes through body cavities.

submucosa - dense irregular connective tissue that supports the mucosa.

submucosal plexus - (Meissner's plexus) part of the enteric nervous system lying in the submucosa layer. Embryologically formed from neural crest cells.

taenia coli - three longitudinal smooth muscle bands around the gastrointestinal tract.

vermiform - (Latin, vermis = "a worm", and forma = "shape") having a worm-like shape, as in the appendix (vermiform appendix).


Cite this page: Hill, M.A. (2014) Embryology Colon Histology 2009. Retrieved September 23, 2014, from https://php.med.unsw.edu.au/embryology/index.php?title=Colon_Histology_2009

What Links Here?
© Dr Mark Hill 2014, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G