RE: Blood cells in Avians

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From:"Kellar, Eric" <kellarec@MSX.UPMC.EDU> (by way of histonet)
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Avian erythrocytes (and nonmammalian ones, generally) are oval in shape, and
have a distinct, centrally located nucleus. Although
size varies somewhat  with sex and breed, avian erythrocytes are typically
about 6.0-8.0  wide and 9.0-12  long. The nucleus is
strongly basophilic and the cytoplasm eosinophilic. Frequently you will be
able to make out a clear area around the nucleus; this is an enlarged
perinuclear space. The space is real-it's present in all nucleated cells-but
its enlargement to the point where it can be seen with a light microscope
is probably a preparation artifact.

There is other cell types in avian blood, although you may have some
difficulty in making them out at first.
The thrombocyte cell has functions similar to those of the platelet in
mammals.  Thrombocytes are smaller than erythrocytes,
have large round nuclei, and in most smears have a faintly bluish tinge to
their cytoplasm. One immediately recognizable feature
in good preparations is a small eosinophilic vacuole located at one end of
the nucleus. It appears as an orange dot in most preparations.

Birds have leukocytes, too, and the most numerous leukocyte is the
lymphocyte. These vary in size (as in mammals) and have a
basophilic cytoplasm and a round nucleus. The cell as a whole is usually
round in smears, and the nucleus may be slightly indented.

Monocytes resemble lymphocytes, but are larger; they frequently have a
vacuolated cytoplasm and granular nuclear chromatin.

One very conspicuous leukocyte is the heterophil. Heterophils have a
cytoplasm which stains little (if at all) so that it appears
clear; the most conspicuous feature of these cells is their rod-shaped,
eosinophilic, granules. The heterophil sometimes has a
distinct ruby-colored central granule; and often in smears the rod-shaped
granules are dissolved, leaving the central one only.

The eosinophil is often mistaken for a heterophil, but it can be
distinguished by its slightly basophilic cytoplasm and granules which
are round, not rod-shaped.

Birds also have basophils, which are much more numerous than those of
mammals. Like those of mammals, they contain large
numbers of granules which stain strongly with basic dyes and have a deep
purple color.

Mature avian erythrocytes are oval-shaped and nucleated. Less mature cells
are rounder in shape and more basophilic in color.
Reticulocytes are normally present in peripheral blood at approximately 1-2%
of the total erythrocyte count. Anisocytosis describes
the degree of variability of cell size. Laboratories employ a variety of
schemes to describe and quantitate the degree of anisocytosis.
Automated erythrocytic analysis can result in a calculated measure of
anisocytosis, the Red Cell Distribution Width (RDW%).
The RDW is a numerical expression of the coefficient of variability of the
mean corpuscular volume(MCV).
A typical normal psittacine RDW% is 10-11%. An increase in RDW% denotes an
increase in anisocytosis.

Polychromasia refers to variation in erythrocyte coloration. This variation
largely relates to the maturation of the cell. The younger
form will appear with bluer cytoplasm in Romanowsky stains; the mature form
will stain uniformly orange-pink. A slight degree of
polychromasia is normal. Increases in polychromasia suggest an increased
bone marrow response. No polychromasia correlates
with non-responsive, anemic patients, which is characterized by all cells
exhibiting the same coloration.

Eric C. Kellar
University of Pittsburgh Medical Center

	From:  Siyami Karahan []
	Sent:  Thursday, November 11, 1999 10:13 AM
	Subject:  Nucleated red blood cells

	 Dear histonetters:

	 Does anyone know what are the life spans of red blood cells in
birds and
	fish? what kind of advantages does a nucleadted blood cell have?

	 Thank you


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