Hématopoïèse

The hématopoïèse is the formation of the blood cells.

The hematopoietic embryonic original cells are at the origin of all the blood lines of cells. While dividing, they give new hematopoietic original cells and cells which will be able to be different, this with an aim of keeping a poll of original cells (this is the case of all the original cells in the bodies). They are able to give, after differentiation, any of the blood cells: red globules, white globules, plates. They are in the red marrow of the bones. These cells are different only when one gene is activated, gene up to now unknown. The specialization of the original cells is a field of key research since it would make it possible to create with large scales in laboratory of the compatible blood cells to the receiver, to very the original cells of the donor.

The hématopoïèse is held at the man, after the birth in the marrow of the bones, and in particular in the adult only in the bone sternal, the bones iliaques and the head of the femur, they are thus places of hematopoietic punctures in the event of suspicion of problems. Before the birth, the hématopoïèse is held initially in the blood small islands of the vitelline blister then in the lymphatic liver, spleen and ganglia.

One distinguishes several stages in the transformation from the original cells into final cells circulating in the blood-vessels.

The original cells are different as progéniteurs who themselves will give place to three processes of Différenciation:

the érythropoïèse,
the leucopoïèse including/understanding the granulopoïèse,
the thrombocytopoïèse.

Érythropoïèse

Process allowing manufacture of the red globules.

Leucopoïèse

Process allowing manufacture of Leucocyte S, under the influence of " interleukines" and of " growth factors of the colonies" (CSF). Different the interleukines is located by numbers, while the growth factors bear the name of the leucocyte which they stimulate.

Thrombocytopoïèse

Process allowing manufacture of the plate S.

Diseases related to the hématopoïèse

They are often due to an excess or a defect of creation of certain blood cells, giving according to, a hemopathy of the blood cells (tumor), aplasia of the red globules.

Hemopathy of the blood globules

leukemia: the tumoral cells are dispersed in blood.
lymphoma: the tumoral cells are dispersed in the secondary lymphoid bodies (ganglion, spleen…).

Aplasia of the blood globules

The role of the blood cells being mainly: the transport of the nutrient O2 and the elimination of part of CO2 by the red globule, the Hémostase by the plates, and immunizing defense; aplasia of a type of globule will give a failure in the function which is intended to him and will give respectively mainly a tiredness, a facility with the hemorrhages, and a higher risk of infection. To note that these aplasias can be due to a lack of certain elements: the lack of important iron gives a Anémie, the lack of folate and of vitamin B12 can also cause aplasias.

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