Editing Haematopoiesis (section)

== Process ==

=== Haematopoietic stem cells (HSCs) ===
{{Main|Hematopoietic stem cell}}
[[Hematopoietic stem cell|Haematopoietic stem cell]]s (HSCs) reside in the medulla of the bone ([[bone marrow]]) and have the unique ability to give rise to all of the different mature blood cell types and tissues.<ref name="Birbrair n/a–n/a"/> HSCs are self-renewing cells: when they differentiate, at least some of their daughter cells remain as HSCs so the pool of stem cells is not depleted.<ref name="Monga">{{Cite journal |vauthors=Monga I, Kaur K, Dhanda S |date=March 2022 |title=Revisiting hematopoiesis: applications of the bulk and single-cell transcriptomics dissecting transcriptional heterogeneity in hematopoietic stem cells |journal=Briefings in Functional Genomics |volume=21 |issue=3 |pages=159–176 |doi=10.1093/bfgp/elac002 |pmid=35265979}}</ref> This phenomenon is called [[Asymmetric cell division|asymmetric division.]]<ref>{{Cite journal |last=Morrison |first=J. |last2=Judith Kimble |year=2006 |title=Asymmetric and symmetric stem-cell divisions in development and cancer |url=https://deepblue.lib.umich.edu/bitstream/2027.42/62868/1/nature04956.pdf |journal=Nature |volume=441 |issue=7097 |pages=1068–74 |bibcode=2006Natur.441.1068M |doi=10.1038/nature04956 |pmid=16810241 |s2cid=715049 |hdl-access=free |hdl=2027.42/62868}}</ref> The other daughters of HSCs ([[myeloid]] and [[Lymphatic system|lymphoid]] progenitor cells) can follow any of the other differentiation pathways that lead to the production of one or more specific types of blood cell, but cannot renew themselves. The pool of progenitors is [[Homogeneity and heterogeneity|heterogeneous]] and can be divided into two groups; long-term self-renewing HSC and only transiently self-renewing HSC, also called short-terms.<ref>{{Cite journal |vauthors=Morrison SJ, Weissman IL |date=Nov 1994 |title=The long-term repopulating subset of hematopoietic stem cells is deterministic and isolable by phenotype. |journal=Immunity |volume=1 |issue=8 |pages=661–73 |doi=10.1016/1074-7613(94)90037-x |pmid=7541305}}</ref> This is one of the main vital processes in the body.{{cn|date=December 2024}}

=== Cell types ===
All blood cells are divided into three lineages.<ref>{{Cite web |title=Hematopoiesis from Pluripotent Stem Cells |url=http://www.ebioscience.com/resources/pathways/hematopoiesis-from-pluripotent-sem-cells.htm |access-date=25 April 2020 |website=Antibodies Resource Library |publisher=ThermoFisher Scientific}}</ref>
* [[Red blood cell]]s, which are also called erythrocytes, are the oxygen-carrying [[red blood cell|cell]]s. [[Red blood cells|Erythrocytes]] are functional, and are released into the blood. The number of reticulocytes, which are immature red blood cells, gives an estimate of the rate of [[erythropoiesis]].
* [[Lymphocyte]]s are the cornerstone of the adaptive immune system. They are derived from common lymphoid progenitors. The lymphoid lineage is composed of [[T-cell]]s, [[B-cell]]s, and [[natural killer cells]]. This is [[lymphopoiesis]].
* Cells of the myeloid lineage, which include [[granulocyte]]s, [[megakaryocyte]]s, monocytes, and [[macrophage]]s, are derived from common myeloid progenitors, and are involved in such diverse roles as [[innate immunity]] and [[blood clotting]]. This is [[myelopoiesis]].

[[Granulopoiesis]] (or granulocytopoiesis) is haematopoiesis of granulocytes, except [[mast cell]]s which are granulocytes but with an extramedullar maturation.<ref>{{Cite book |last=Mahler |title=Haschek and Rousseaux's handbook of toxicologic pathology |date=2013 |publisher=Academic Press |others=associate editors, Brad Bolon and Ricardo Ochoa; illustrations editor, Beth W. |isbn=978-0-12-415759-0 |editor-last=Haschek |editor-first=Wanda |edition=Third |location=[S.l.] |page=1863 |editor-last2=Rousseaux |editor-first2=Colin G. |editor-last3=Wallig |editor-first3=Matthew A.}}</ref>

[[Thrombopoiesis]] is haematopoiesis of [[Platelet|thrombocytes (platelets)]].

===Terminology===
Between 1948 and 1950, the Committee for Clarification of the Nomenclature of Cells and Diseases of the Blood and Blood-forming Organs issued reports on the nomenclature of blood cells.<ref>{{Cite journal |date=May 1948 |title=FIRST report of the committee for clarification of the nomenclature of cells and diseases of the blood and blood-forming organs |url=https://academic.oup.com/ajcp/article-abstract/18/5_ts/443/4828542 |journal=American Journal of Clinical Pathology |volume=18 |issue=5 |pages=443–50 |doi=10.1093/ajcp/18.5_ts.443 |pmid=18913573 |url-access=limited}}</ref><ref>{{Cite journal |date=June 1950 |title=THIRD, fourth and fifth reports of the committee for clarification of the nomenclature of cells and diseases of the blood and blood-forming organs |url=https://academic.oup.com/ajcp/article-abstract/20/6/562/1767294 |journal=American Journal of Clinical Pathology |volume=20 |issue=6 |pages=562–79 |doi=10.1093/ajcp/20.6.562 |pmid=15432355 |url-access=limited}}</ref> An overview of the terminology is shown below, from earliest to final stage of development:{{cn|date=September 2024}}
* [root]blast
* pro[root]cyte
* [root]cyte
* meta[root]cyte
* mature cell name

The root for erythrocyte colony-forming units (CFU-E) is "rubri", for granulocyte-monocyte colony-forming units (CFU-GM) is "granulo" or "myelo" and "mono", for lymphocyte colony-forming units (CFU-L) is "lympho" and for megakaryocyte colony-forming units (CFU-Meg) is "megakaryo". According to this terminology, the stages of red blood cell formation would be: rubriblast, prorubricyte, rubricyte, metarubricyte, and erythrocyte. However, the following nomenclature seems to be, at present, the most prevalent:

{| class="wikitable"
! Committee || "lympho" || "rubri" || "granulo" or "myelo" || "mono" || "megakaryo"
|-
|''Lineage''||[[Lymphoid]]||[[Myeloid]]|| Myeloid || Myeloid || Myeloid
|-
|''CFU''||[[CFU-L]]||[[CFU-GEMM]]→[[CFU-E]]|| CFU-GEMM→[[CFU-GM]]→[[CFU-G]]|| CFU-GEMM→[[CFU-GM]]→[[CFU-M]]|| CFU-GEMM→[[CFU-Meg]]
|-
|''Process''||[[lymphocytopoiesis]]||[[erythropoiesis]]||[[granulocytopoiesis]]||[[monocytopoiesis]]||[[thrombocytopoiesis]]
|-
|''[root]blast''||[[Lymphoblast]]||[[Proerythroblast]]||[[Myeloblast]]||[[Monoblast]]||[[Megakaryoblast]]
|-
|''pro[root]cyte''||[[Prolymphocyte]]||[[Polychromatophilic erythrocyte]]||[[Promyelocyte]]||[[Promonocyte]]||[[Promegakaryocyte]]
|-
|''[root]cyte''|| – ||[[Normoblast]]||[[Eosinophilic myelocyte|Eosino]]/[[neutrophilic myelocyte|neutro]]/[[basophilic myelocyte]]||  ||[[Megakaryocyte]]
|-
|''meta[root]cyte''|| Large [[lymphocyte]]||[[Reticulocyte]]|| Eosinophilic/neutrophilic/basophilic [[metamyelocyte]], Eosinophilic/neutrophilic/basophilic [[band cell]]||[[Early monocyte]]|| -
|-
|''mature cell name''|| Small [[lymphocyte]]||[[Erythrocyte]]||[[granulocytes]] ([[Eosinophil|Eosino]]/[[neutrophil|neutro]]/[[basophil]]) ||[[Monocyte]]||[[thrombocytes]] ([[Platelets]])
|}

[[Osteoclast]]s also arise from hemopoietic cells of the monocyte/neutrophil lineage, specifically CFU-GM.