notes by dr Claudio Italiano
The blood, a liquid consistency tissue, of a characteristic red color, is
contained in the cardio-arterial-capillary-venous system, in which it is
subjected to continuous circulation, except for its stagnation in the lacunae.
Can be considered formed by two distinct components:
a) the plasma
b) the corpus poured share, represented by red blood cells, white blood cells
and platelets.
Under normal conditions the red blood cells, the white blood cells and the platelets are present in the circulating blood
- Red blood cells or erythrocytes or red blood cells. They constitute the most
numerous figurative elements of the blood and give the blood the characteristic
red color by means of the respiratory pigment contained in them, called "hemoglobin".
Normally they are elements without a nucleus. On observation their appearance
may appear different depending on the medium used for observation or if they are
observed in fresh or after coloring.
Erythropoiesis means the biological process that leads to the formation of red blood cells; for erythrone we mean the whole of erythropoietic tissue and of circulating erythrocyte mass. Erythrocyte count: when counting under a microscope, counting with electronic cell counters tends to be replaced, much safer. Adult white males have an average of 4,800,000 globules per mm3, adult white females averaging 4,300,000, while adult blacks have more, on average 4,400,000 and black women average 3,800,000. Normal erythrocytes have a biconcave lens shape, with a diameter oscillating between 6.7-7.7 μm and an average thickness of 2 + 0.2 μl. They are in the normal condition without nucleus and are stained with the common cytoplasmic dyes with a greater intensity at the periphery. Plasma is, under normal conditions, a yellow liquid with a slight greenish tinge, due to the proportion of bilirubin present in it and to a lipocromo, the "lutein". It normally represents the main part of the blood (about 55% in men and 58% in women), the remaining part being the corpuscular component. The plasma / cellular ratio is the hematocrit or Ht value which is expressed by this percentage. Both the liquid and the corpuscular shares normally participate in its maintenance and in some pathological conditions this relationship can be altered (hemorrhages, primitive and secondary polyglobulias); modifications can also be caused artificially.
Normal hematocrit values:
- men: 40-45%;
- women: 37-47%;
- full-term newborns (umbilical cord blood): 44-62%;
- children (1st year of life): 36-44%;
- children from 10 to 12 years old: 37-44%.
Reduction of the hematocrit value can occur due to a decrease in red blood cells
or a reduction in their volume, and therefore can be found in the case of:
- anemias (be they normocytic, microcytic or macrocytic);
- true microcitemia;
- hemodilution.
On the other hand, an increase in the hematocrit value can occur if:
- primitive or secondary polycythemia;
- hemoconcentration.
Another parameter of considerable importance is that constituted by the
determination of the circulating blood mass. It is necessary to be able to
obtain this value to determine the plasma volume. For this purpose we use
colorants (normally Evans blue is used), which have the property to bind to
plasma proteins and stay in the circulatory stream for a long time. More
recently, the method of human albumin labeled with radioactive chromium (51Cr)
has been introduced.
Normally the plasma volume is in the man of 43.1 cm3 / kg of body weight, while
in the woman it is about 41.5 cm3 / kg.
The body hematocrit value is derived from the ratio between the global
erythrocyte volume and the total blood volume. Under normal conditions the
values oscillate between 60 and 80 cc / kg.
For the determination of the global erythrocyte volume, the method of the
haemats marked with radioactive chromium (5lCr) is normally used, which is
preferred to other methods because of its simplicity of execution and the
precision of the values obtained (the normal values obtained with this
method are: men 26-33 cc / kg, women 22-29 cc / kg).
In different physiological conditions (advanced age, pregnancy, position of the
body, etc.) or pathological (burns, cirrhosis of the liver with ascites, kidney
disease, circulatory decompensation, hemorrhages,
Under normal conditions the organs that generate the corpuscular elements of the
blood (hemopoietic organs) are in the adult subject: the bone marrow, the spleen
and the lymphatic tissues. Red blood cells, platelets, granulocytes,
historeticular cells are generated in the bone marrow and only in a small part
are monocytes, lymphocytes and plasma cells.
In the spleen and lymphatic organs originate: lymphocytes, plasma cells,
historeticular cells and monocytes.
The modalities with which the immature elements of the haematopoietic matrix
reaches the mature elements normally present in the peripheral blood are still
today the object of discussion. Referring to the unitary theory of the Ferrata,
the complete scheme of the hematopoiesis should follow the following path:
The bone marrow occupies the long bone canal, the intertrabecular spaces of the
spongiosa of the flat and short bones and also of the epiphyses of all long
bones.
His study, therefore, is useful in all those conditions in which there is a
suspicion of an affliction of hemopoiesis. Through his biopsy you can have
information about:
- the richness of myeloid tissue;
- the various cytological characteristics of the medullary elements;
- the percentage ratios between the various medullary elements;
- the reproductive and maturative capacity of the cells;
- any alteration of the hematopoiesis and the presence of elements normally
absent in the bone marrow.
Furthermore, its culture can be useful in various infectious diseases.
The technique normally used for bone marrow biopsy is that of bone marrow biopsy
by means of a special needle.
A biopsy needle is usually used, equipped with a mandrel, having a diameter of
1-2 mm, to which a 4 cm 'syringe is inserted.
The points of choice for the puncture are usually:
- the sternum;
- the iliac crest;
- the vertebral spinous apophysis.
Thus the cytological composition of the marrow can be studied; that is, the
myelogram, whose pattern varies according to the different populations and above
all according to the age of the subject:
The numerical data of the myelogram allow to immediately deduce an index and
precisely that relating to erythropoiesis and leucopoiesis. Under normal
conditions the leuco-erythropoietic ratio is around 2. An increase in said
relationship occurs in all those conditions in which a hyperplasia of the white
series occurs, namely:
- in infectious diseases;
- in myeloid leukosis;
A reduction of said relationship occurs due to a hyperplasia of the
erythroblastic series, which can occur in:
- erytheremal myelosis;
- in hemolytic syndromes in general;
- in favism after a jaundice-hemoglobinuric crisis.
Reticular cells 0.1-2%
hemocytoblasts 0.1-1%
myeloblasts 0.1-3.5%
0.5-5% promyelocytes
neutrophil myelocytes 5.0-25%
0.1-3% eosinophil myelocytes
basophil myelocytes 0.0-0.5%
10-30% metamyelocytes
polymorphonuclear neutrophils 7-25%
eosinophilic polymorphonucleate 0.2-3%
basophilic polymorphonucleate 0.0-0.5%
5.0-20% lymphocytes
monocytes 0.0-0.2%
megakaryocytes 0.1-0.5%
plasma cells 0.1-3.5%
Pro-thromboblastic 0.5-5%
polychromatic erythroblasts 2.0-20%
Orthochromatic erythroblasts 2.0-10%