morphology of red blood cells
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Red cell morphology
Normal Red CellFragile, Biconcave, disk like structure.
Have smooth round surface
Diameter ranges from 7.5-7.8µm.
Appears to be of the same size as the nucleus of the small lymphocyte.
Have no nucleus
Whole cell is filled with the HAEMOGLOBIN.
The red colour of red cells is due to the presence or haemoglobin
RBCs survive for approximately 120 days in the peripheral blood
Normal red cell
Normocytic & Normochromic•Normocytic: The term used to express RBCs of normal size is
normocytic.
•Normochromic: Mature red blood cells, under normal
circumstances, will also have an appropriate hemoglobin content, giving
them a red-orange appearance on Wright-stained smears. These cells
will display a central pallor no larger than 3 microns in diameter. This
normal morphology is indicated by the term normochromic.
•It is paramount for RBCs to contain an adequate amount of
hemoglobin for the purpose of transporting oxygen to the tissues and
carbon dioxide back to the lungs.
ABNORMALITIES OF RED CELLS
3 types of abnormalities may occur in red blood cells
i.Anisocytosis: If the size of RBC varies, in the same blood film,
beyond normal limits, it is termed anisocytosis.
ii.Poikilocytosis: When the shapes of RBCs vary more than
expected in normal individuals, in the blood film, it is termed
poikilocytosis.
iii.INCLUSIONS IN RBC: abnormal structures present in red
cells having certain staining charecteristics
Anisocytosis:
Poikilocytosis:
Anisocytosis:
Variations in size are as follows:1)MACROCYTOSIS: When the average size of RBC is more than normal, it is termed macrocytosis.Causes Of Macrocytosis:liver diseasemegaloblastic anaemiaaplastic anaemia,obstructive airway diseaseexcess of alcohol,
Cont…MIROCYTOSIS: When the average size of RBC ina blood film is less than normal it is termed microcytosis.Causes Of Microcytosis:iron deficiency anaemiathalassaemia.There will decrease in MCV.Should be distingused from red cell fragmentation. If in association with decrease in MCV it will be microcytosis.
POIKILOCYTOSISAbnormality in shape may be of the following types:1.Spherocytes2.Ovalocytes3.Burr cells4.Crenated red cells5.Schistocytes6.Tear drop cells7.Acanthocytes8.Target cells9.Sickle cells 10.Pencil cells:
Cont….Spherocytes: small densely staining spherical red cells with no central pallor area
Causes:•Haemolytic anaemia• drugs induced•snake venom•infection with C. perfringens•hereditary spherocytosis•ABO haemolytic disease of the newborn
CONTINU…..
Ovalocytes: these are oval shaped red cells. About 10% RBC in a normal blood film, particularly at the tail end, appear oval and less commonly elliptical in shape.
Causes:•Iron deficiency anaemia,•megaloblastic anaemia
Cont….
Pencil cells: Elongated narrow red cellsFeature of iron deficiency anaemia
Cont….Target : these are hypochromic red cells showing central spot of HbCauses:•Thalassaemia syndromes•sickle cell disease•HbC disease•HbD disease•obstructive jaundice•liver disease•postsplenectomy
Cont....Sickle cells: These are thin crescent shaped, or boat shaped cells elongated, deeply staining red cells with pointed ends.These may be straight, curved or of various other shapes. These are produced by polymerisation of HbS in sickle cell disease.,Causes: Sickle cell disease, including sickle cellanaemia (S/S) sickle cell/ thalassaemia,
Cont....
Sickle cells:
Cont....Acanthocytes: Irregularly crenated cells with irregularly spaced sharp projections. Small number of spicules of inconstant length, thickness , shape ,irregularly disposed over the surface of the cell.
Causes: Associated with abnormal phospholipids metabolism or with inherited abnormalities of red cell membrane proteins. After spleenectomy, hypospleenism and in sever liver disease.
Cont….
Tear drop : Cells shaped like tear drops. It is also called pear shaped cell. these cells are usually found In iron deficiency anaemia
Cont….
Schistocytes: These are fragmented red blood cells of various shapes and sizes.
Cause: Associated with red cell damage due tosevere burns, drugs, toxins, DIC. Also found in uraemia
CRENATED RED CELLS: Echinocytes or crenated cells have evenly distributed blunt spicules of uniform size on their surface.A few crenated cells are seen in the blood film of healthy subjects.These are formed if anticoagulated blood is allowed to stand for long periods
Cont….
Burr cells: Burr cells are also echinocytes but their spicules are reversible.
Causes: •Uraemia•acute blood loss•Pyruvate kinase deficiency
Cont….STOMATOCYTOSISIn dry films , the central biconcave area appears slit like. In wet preparations, the stomatocyte is a cup shaped red cell.Also occurs as an artifact because the change can be produced by decrease pH .
They are found in:•Hereditary stomatocytosis•Liver disease•Alcoholism
Cont…Hypochromasia or hypochromic red cells: these are the red cells which are deficient in Hb. They appear ring shaped because the centeral palor is increased.
They are found in• iron deficiency anaemia•Thalassaemia•sideroblastic anaemia
Dimorphic appearance
It is the Presence of two different populationsof red cells, e.g:• hypochromic cells with normal red cells, or•hypochromic cells with macrocytic cells
Commonly seen following successful treatment for anemia and post-blood transfusion
INCLUSIONS IN RBC:
Abnormal structures which are present In red cells are called inclusions. These are normally abscent in red cells.These includes:
•Howell-Jolly bodies•Cabot Rings •Heinz Bodies•Siderocytes•Basophilic stippling•Malarial parasite
Cont….Howell-Jolly bodies:These are small (<1 μm in diameter) rounded fragments of the nuclear material staining reddish-blue to blue-black. These usually occur singly in RBC but may be multiple. During maturation in the bone marrow erythrocytes normally expel their nuclei, but in some cases a small portion of DNA remains.Causes:•splenectomy •Splenic atrophy •alcoholism•sickle cell anaemia•megaloblastic anaemia.
Cont….Cabot rings: These are Reddish-blue threadlike rings in
RBCs. These are remnants of the nuclear membrane
and appear as a ring or figure 8 pattern.
Very rare finding in patients
with Megaloblastic anemia
severe anemia's
lead poisoning
and dyserythropoiesis
Cont….
Heinz Bodies:•Represent areas of denatured hemoglobin. They appear highly
refractile bodies near the pariphery of cell In unstained wet cover
glass preparation.
•With a supravital stain like crystal violet, Heinz bodies appear as
round blue precipitates.
•Presence of Heinz bodies indicates red cell injury and is usually
associated with G6PD-deficiency.
Heinz Bodies
Siderocytes:
these are red cells containing non haemoglobin iron granules.
Iron granules appear bright blue.
They are found in haemolytic anaemia.
Cont….Basophilic stippling: These are fine to coarse, deep blue to purple,
small but multiple inclusions of varying sizes.
They are given the name due to purplish colour.
Normally one in 10000 cells may show basophilic stippling.
Increased no is seen in:
•Thalassaemia
•megaloblastic anaemia
•liver disease
•lead poisoning
•infections
Cont….Malarial parasite:Malarial parasite may be present in red cells in verious forms like:
•Trophozoite•Schizont•gametocytes
ROULEAUX FORMATIONA stack like arrangement of red blood cells
in blood or in diluted suspensions of blood
in which their biconcave surfaces are next
to each other.
The RBC's here have stacked together in
long chains. This is known as "rouleaux
formation"
It happens with increased serum proteins,
particularly fibrinogen and globulins.
CHANGES ASSOSIATED WITH A COMPANSATORY INCREASE IN
ERYTHROPOIESES
POLYCHROMASIARefers to having red blood cell of
multiple colors, particularly gray-
blue.
This is due to differing amounts
of haemoglobin in each cell , which
is due to inappropriate, premature
release from the bone marrow:
ERYTHROBLASTEMIAThe presence in the peripheral blood of abnormally large number nucleated red cells.They are found in sever anemia.Large number is characteristic of haemolytic disease of newborn.After spleenectamy.Sickle cell anemia.Leukemia .Myelofibrosis.
PIMS