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Bone marrow is a semi-solid tissue found within the spongy (also known as cancellous) portions of bones. [2] In birds and mammals, bone marrow is the primary site of new blood cell production (or haematopoiesis). [3] It is composed of hematopoietic cells, marrow adipose tissue, and supportive stromal cells.
When bone marrow develops, it eventually assumes the task of forming most of the blood cells for the entire organism. [3] However, maturation, activation, and some proliferation of lymphoid cells occurs in the spleen, thymus, and lymph nodes. In children, haematopoiesis occurs in the marrow of the long bones such as the femur and tibia.
A granulocyte, also referred to as a polymorphonuclear leukocyte (PMN), is a type of white blood cell that has multi lobed nuclei, usually containing three lobes, and has a significant amount of cytoplasmic granules within the cell. [1] Granulopoiesis takes place in the bone marrow. [2]
A comprehensive diagram of human hematopoiesis. Granulopoiesis consists of 5 stages, in which the myeloblast is the first recognizable cell. Next in the differentiation sequence is the monoblast and the promyelocyte, which can develop into one of three different precursor cells: the neutrophilic, basophilic or eosinophilic myelocyte.
Hematopoietic stem cells (HSCs) are the stem cells [1] that give rise to other blood cells.This process is called haematopoiesis. [2] In vertebrates, the first definitive HSCs arise from the ventral endothelial wall of the embryonic aorta within the (midgestational) aorta-gonad-mesonephros region, through a process known as endothelial-to-hematopoietic transition.
Bone marrow, also known as myeloid tissue in red bone marrow, can be found in almost any bone that holds cancellous tissue. In newborns , all such bones are filled exclusively with red marrow or hematopoietic marrow, but as the child ages the hematopoietic fraction decreases in quantity and the fatty/ yellow fraction called marrow adipose ...
White blood cells are generally larger than red blood cells. They include three main subtypes: granulocytes, lymphocytes and monocytes. [2] All white blood cells are produced and derived from multipotent cells in the bone marrow known as hematopoietic stem cells. [3] Leukocytes are found throughout the body, including the blood and lymphatic ...
In hematology, myelopoiesis in the broadest sense of the term is the production of bone marrow and of all cells that arise from it, namely, all blood cells. [1] In a narrower sense, myelopoiesis also refers specifically to the regulated formation of myeloid leukocytes (), including eosinophilic granulocytes, basophilic granulocytes, neutrophilic granulocytes, and monocytes.