Myeloid tissue, in the

bone marrow Bone marrow is a semi-solid tissue found within the spongy (also known as cancellous) portions of bones. In birds and mammals, bone marrow is the primary site of new blood cell production (or haematopoiesis). It is composed of hematopoietic ce ...

sense of the word ''

myeloid Myeloid tissue, in the bone marrow sense of the word '' myeloid'' ('' myelo-'' + ''-oid''), is tissue of bone marrow, of bone marrow cell lineage, or resembling bone marrow, and myelogenous tissue (''myelo-'' + '' -genous'') is any tissue of, ...

'' ('' myelo-'' + ''

-oid In linguistics, a suffix is an affix which is placed after the stem of a word. Common examples are case endings, which indicate the grammatical case of nouns, adjectives, and verb endings, which form the conjugation of verbs. Suffixes can carry ...

''), is tissue of bone marrow, of bone marrow cell lineage, or resembling bone marrow, and myelogenous tissue (''myelo-'' + '' -genous'') is any tissue of, or arising from, bone marrow; in these

senses A sense is a biological system used by an organism for sensation, the process of gathering information about the world through the detection of stimuli. (For example, in the human body, the brain which is part of the central nervous system rec ...

the terms are usually used

synonym A synonym is a word, morpheme, or phrase that means exactly or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are all ...

ously, as for example with chronic myeloid/myelogenous leukemia. In hematopoiesis, myeloid or myelogenous cells are

blood cell A blood cell, also called a hematopoietic cell, hemocyte, or hematocyte, is a cell produced through hematopoiesis and found mainly in the blood. Major types of blood cells include red blood cells (erythrocytes), white blood cells (leukocytes), ...

s that arise from a progenitor cell for

granulocyte Granulocytes are cells in the innate immune system characterized by the presence of specific granules in their cytoplasm. Such granules distinguish them from the various agranulocytes. All myeloblastic granulocytes are polymorphonuclear. They ha ...

s, monocytes, erythrocytes, or platelets (the

common myeloid progenitor CFU-GEMM is a colony forming unit that generates myeloid cells. CFU-GEMM cells are the oligopotential progenitor cells for myeloid cells; they are thus also called common myeloid progenitor cells or myeloid stem cells. "GEMM" stands for granulocy ...

, that is, CMP or CFU-GEMM), or in a narrower sense also often used, specifically from the lineage of the

myeloblast The myeloblast is a unipotent stem cell which differentiates into the effectors of the granulocyte series. It is found in the bone marrow. Stimulation of myeloblasts by G-CSF and other cytokines triggers maturation, differentiation, proliferation a ...

(the

myelocyte A myelocyte is a young cell of the granulocytic series, occurring normally in bone marrow (can be found in circulating blood when caused by certain diseases). Structure When stained with the usual dyes, the cytoplasm is distinctly basophilic ...

s, monocytes, and their daughter types). Thus, although all blood cells, even lymphocytes, are normally born in the bone marrow in adults, myeloid cells in the narrowest sense of the term can be distinguished from lymphoid cells, that is, lymphocytes, which come from common lymphoid progenitor cells that give rise to

B cell B cells, also known as B lymphocytes, are a type of white blood cell of the lymphocyte subtype. They function in the humoral immunity component of the adaptive immune system. B cells produce antibody molecules which may be either secreted or ...

s and T cells. Those cells' differentiation (that is, lymphopoiesis) is not complete until they migrate to lymphatic organs such as the spleen and thymus for programming by antigen challenge. Thus, among leukocytes, the term ''myeloid'' is associated with the

innate immune system The innate, or nonspecific, immune system is one of the two main immunity strategies (the other being the adaptive immune system) in vertebrates. The innate immune system is an older evolutionary defense strategy, relatively speaking, and is the ...

, in contrast to ''lymphoid'', which is associated with the adaptive immune system. Similarly, ''myelogenous'' usually refers to nonlymphocytic white blood cells, and ''erythroid'' can often be used to distinguish "erythrocyte-related" from that sense of ''myeloid'' and from ''lymphoid''. The word '' myelopoiesis'' has several senses in a way that parallels those of ''myeloid'', and myelopoiesis in the narrower sense is the regulated formation specifically of myeloid leukocytes (myelocytes), allowing that sense of ''myelopoiesis'' to be contradistinguished from erythropoiesis and lymphopoiesis (even though all blood cells are normally produced in the marrow in adults). Myeloid neoplasms always concern bone marrow cell lineage and are related to

hematopoietic Haematopoiesis (, from Greek , 'blood' and 'to make'; also hematopoiesis in American English; sometimes also h(a)emopoiesis) is the formation of blood cellular components. All cellular blood components are derived from haematopoietic stem cells. ...

cells. Myeloid tissue can also be present in the liver and spleenSemester 4 medical lectures at Uppsala University 2008 by Leif Jansson in fetuses, and sometimes even in adults as well, which leads to extramedullary hematopoiesis. There is one other sense of ''myeloid'' that means "pertaining to the spinal cord", but it is much less commonly used. ''Myeloid'' should not be confused with '' myelin'', referring to an insulating layer covering the axons of many neurons.

References

External links

{{Myeloid blood cells and plasma Blood cells Tissues (biology)

See also

References

External links