World Library  
Flag as Inappropriate
Email this Article

Codocyte

Article Id: WHEBN0002929810
Reproduction Date:

Title: Codocyte  
Author: World Heritage Encyclopedia
Language: English
Subject: Sepsis, Macrocytic anemia, Abnormal basal metabolic rate, Hypoalbuminemia, ICD-10 Chapter XVIII: Symptoms, signs and abnormal clinical and laboratory findings
Collection:
Publisher: World Heritage Encyclopedia
Publication
Date:
 

Codocyte

Codocytes in human blood (Giemsa stain)


Codocytes, also known as target cells or Mexican hat cells,[1][2] are red blood cells that have the appearance of a shooting target with a bullseye. In optical microscopy these cells appear to have a dark center (a central, hemoglobinized area) surrounded by a white ring (an area of relative pallor), followed by dark outer (peripheral) second ring containing a band of hemoglobin. However in electron microscopy they appear very thin and bell shaped. Because of their thinness they are referred to as leptocytes and because of the wavy bowl shape they are referred to as Mexican hat cells. On routine smear morphology, some people like to make a distinction between leptocyes and codocytes- suggesting that in leptocytes the central spot is not completely detached from the peripheral ring, i.e. the pallor is in a C shape rather than a full ring.[3]

These cells are characterized by a disproportional increase in the ratio of surface membrane area to volume. This is also described as a "relative membrane excess." It is due to either increased red cell surface area (increased beyond normal), or else a decreased intracellular hemoglobin content (which may cause an abnormal decrease in cell volume without affecting the amount of membrane area). The increase in the surface area to volume ratio also gives the cell decreased osmotic fragility, as it allows it to take up more water for a given amount of osmotic stress.

In vivo (within the blood vessel), the codocyte is a bell-shaped cell. It assumes a "target" configuration only when processed to obtain a blood film. In the film these cells appear thinner than normal, primarily due to their pallor (by which thickness is judged on microscopy).[4]

Contents

  • Causes 1
  • Symptoms 2
  • References 3
  • External links 4

Causes

Target cells may appear in association with the following conditions:

In patients with obstructive liver disease, lecithin cholesterol acetyltransferase activity is depressed, which increases the cholesterol-to-phospholipid ratio and produces an absolute increase in the surface area of the red cell membrane. In contrast, membrane excess is only relative in patients with iron-deficiency anemia and thalassemia because of the reduced quantity of intracellular hemoglobin.[4] When a cell membrane collapses it becomes static and stops pulsating.[6] Target cell formation decreases the amount of oxygen that is circulated through the blood and unable to deliver it to all areas of the body.[7]

Symptoms

Elevations in target cells are the result of a shift in the exchange equilibrium between the red blood cells and the cholesterol. Also the surface membrane to volume ratio is increased.[8] Target cells are more resistant to osmotic lysis, which is mostly seen in dogs. Hypochromic cells in iron deficiency anemias also can show a target appearance.[9] Target cells are abnormally resistant to saline.

References

  1. ^ "Mexican Hat Cell". 
  2. ^ "The Target Cell: An Overview". Retrieved 2009-02-08. 
  3. ^ Clinical Hematology: Theory and Procedures, Volume 936 By Mary Louise Turgeon, Lippincott Williams & Wilkins, 07-Dec-2004 - Chapter 6, p 103of 570
  4. ^ a b William's Haematology, 7th Edition
  5. ^ Tierney, Lawrence M.; McPhee, Stephen J.; Papadakis, Maxine A. (2006). Current Medical Diagnosis and Treatment 2007 (Current Medical Diagnosis and Treatment). McGraw-Hill Professional. p. 498.  
  6. ^ innovateus.net
  7. ^ e.howhealth.com
  8. ^ biomedx.livebloodunderthemicroscope
  9. ^ cornell.edu.targetcells

External links

  • http://arbl.cvmbs.colostate.edu
  • http://biomedx.com/microscopes/training/LB2.html
  • http://www.ornl.gov
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and USA.gov, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for USA.gov and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
 
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
 
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.
 


Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.