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Haematopoiesis

Haematopoiesis is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Haematopoiesis rather than just read about it. In short: Haematopoiesis (; from Ancient Greek αἷμα (haîma) 'blood' and ποιεῖν (poieîn) 'to make'; also hematopoiesis in US English, sometimes h(a)emopoiesis) is the formation of blood cellular components. All cellular blood components are derived from haematopoietic stem cells.

Haematopoiesis — main illustration
Haematopoiesis — illustration

Key takeaways

  • Haematopoiesis belongs to science; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect Haematopoiesis to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Haematopoiesis from memory before moving on to harder problems.

Reference excerpt

Haematopoiesis (; from Ancient Greek αἷμα (haîma) 'blood' and ποιεῖν (poieîn) 'to make'; also hematopoiesis in US English, sometimes h(a)emopoiesis) is the formation of blood cellular components. All cellular blood components are derived from haematopoietic stem cells. In a healthy adult human, roughly ten billion (1010) to a hundred billion (1011) new blood cells are produced per day, in order to maintain steady state levels in the peripheral circulation.

Process

Haematopoietic stem cells (HSCs)

Haematopoietic stem cells (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. 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. This phenomenon is called asymmetric division. The other daughters of HSCs (myeloid and 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 heterogeneous and can be divided into two groups; long-term self-renewing HSC and only transiently self-renewing HSC, also called short-terms. This is one of the main vital processes in the body.

Cell types All blood cells are divided into three lineages.

Red blood cells, which are also called erythrocytes, are the oxygen-carrying 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. Lymphocytes are the cornerstone of the adaptive immune system. They are derived from common lymphoid progenitors. The lymphoid lineage is composed of T-cells, B-cells, and natural killer cells. This is lymphopoiesis. Cells of the myeloid lineage, which include granulocytes, megakaryocytes, monocytes, and macrophages, 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 cells which are granulocytes but with an extramedullar maturation. Thrombopoiesis is haematopoiesis of 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. An overview of the terminology is shown below, from earliest to final stage of development:

[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:

Osteoclasts also arise from hemopoietic cells of the monocyte/neutrophil lineage, specifically CFU-GM.

Location

In developing embryos, blood formation occurs in aggregates of blood cells in the yolk sac, called blood islands. As development progresses, blood formation occurs in the spleen, liver and lymph nodes. When bone marrow develops, it eventually assumes the task of forming most of the blood cells for the entire organism. 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. In adults, it occurs mainly in the pelvis, cranium, vertebrae, and sternum.

Extramedullary In some cases, the liver, thymus, and spleen may resume their haematopoietic function, if necessary. This is called extramedullary haematopoiesis. It may cause these organs to increase in size substantially. During fetal development, since bones and thus the bone marrow develop later, the liver functions as the main haematopoietic organ. Therefore, the liver is enlarged during development. Extramedullary haematopoiesis and myelopoiesis may supply leukocytes in cardiovascular disease and inflammation during adulthood. Splenic macrophages and adhesion molecules may be involved in regulation of extramedullary myeloid cell generation in cardiovascular disease.

Maturation

As a stem cell matures it undergoes changes in gene expression that limit the cell types that it can become and moves it closer to a specific cell type (cellular differentiation). These changes can often be tracked by monitoring the presence of proteins on the surface of the cell. Each successive change moves the cell closer to the final cell type and further limits its potential to become a different cell type.

… excerpt ends here. Continue reading the full article.

Illustrations

Haematopoiesis: Diagram showing the development of different blood cells from haematopoietic stem cell to mature cells
Diagram showing the development of different blood cells from haematopoietic stem cell to mature cells
Haematopoiesis: Sites of haematopoiesis (human) in pre- and postnatal periods
Sites of haematopoiesis (human) in pre- and postnatal periods
Haematopoiesis: More detailed and comprehensive diagram that shows the development of different blood cells in humans:The morphological characteristics of the hematopoietic cells are shown as seen in a Wright's stain, May-Giemsa stain or May-Grünwald-Giemsa stain. Alternative names of certain cells are indicated between parentheses.Certain cells may have more than one characteristic appearance. In these cases, more than one representation of the same cell has been included.Together, the monocyte and the lymphocytes comprise the agranulocytes, as opposed to the granulocytes (basophil, neutrophil and eosinophil) that are produced during granulopoiesis.B., N. and E. stand for Basophilic, Neutrophilic and Eosinophilic, respectively – as in Basophilic promyelocyte. For lymphocytes, the T and B are actual designations.The polychromatic erythrocyte (reticulocyte) at the right shows its characteristic appearance when stained with methylene blue or Azure B.The erythrocyte at the right is a more accurate representation of its appearance in reality when viewed through a microscope.Other cells that arise from the monocyte: osteoclast, microglia (central nervous system), Langerhans cell (epidermis), Kupffer cell (liver).For clarity, the T and B lymphocyte are split to better indicate that the plasma cell arises from the B-cell. Note that there is no difference in the appearance of B- and T-cells unless specific staining is applied.
More detailed and comprehensive diagram that shows the development of different blood cells in humans:The morphological characteristics of the hematopoietic cells are shown as seen in a Wright's stain, May-Giemsa stain or May-Grünwald-Giemsa stain. Alternative names of certain cells are indicated between parentheses.Certain cells may have more than one characteristic appearance. In these cases, more than one representation of the same cell has been included.Together, the monocyte and the lymphocytes comprise the agranulocytes, as opposed to the granulocytes (basophil, neutrophil and eosinophil) that are produced during granulopoiesis.B., N. and E. stand for Basophilic, Neutrophilic and Eosinophilic, respectively – as in Basophilic promyelocyte. For lymphocytes, the T and B are actual designations.The polychromatic erythrocyte (reticulocyte) at the right shows its characteristic appearance when stained with methylene blue or Azure B.The erythrocyte at the right is a more accurate representation of its appearance in reality when viewed through a microscope.Other cells that arise from the monocyte: osteoclast, microglia (central nervous system), Langerhans cell (epidermis), Kupffer cell (liver).For clarity, the T and B lymphocyte are split to better indicate that the plasma cell arises from the B-cell. Note that there is no difference in the appearance of B- and T-cells unless specific staining is applied.
Haematopoiesis: Diagram including some of the important cytokines that determine which type of blood cell will be created.[23] SCF= Stem cell factor; Tpo= Thrombopoietin; IL= Interleukin; GM-CSF= Granulocyte Macrophage-colony stimulating factor; Epo= Erythropoietin; M-CSF= Macrophage-colony stimulating factor; G-CSF= Granulocyte-colony stimulating factor; SDF-1= Stromal cell-derived factor-1; FLT-3 ligand= FMS-like tyrosine kinase 3 ligand; TNF-a = Tumour necrosis factor-alpha; TGFβ = Transforming growth factor beta[23][24]
Diagram including some of the important cytokines that determine which type of blood cell will be created.[23] SCF= Stem cell factor; Tpo= Thrombopoietin; IL= Interleukin; GM-CSF= Granulocyte Macrophage-colony stimulating factor; Epo= Erythropoietin; M-CSF= Macrophage-colony stimulating factor; G-CSF= Granulocyte-colony stimulating factor; SDF-1= Stromal cell-derived factor-1; FLT-3 ligand= FMS-like tyrosine kinase 3 ligand; TNF-a = Tumour necrosis factor-alpha; TGFβ = Transforming growth factor beta[23][24]

Worked examples

Example 1 — a first encounter with Haematopoiesis

Start with the simplest possible case. Write down what Haematopoiesis claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Haematopoiesis before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Haematopoiesis ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Haematopoiesis

In research
Haematopoiesis appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses Haematopoiesis in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
Haematopoiesis is common in secondary-school and first-year university syllabi. It links to neighbouring topics Hematopoiesis, Histology, so understanding it makes those chapters shorter.
In everyday life
Look for Haematopoiesis outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.
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How to study Haematopoiesis in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Haematopoiesis means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Haematopoiesis out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Haematopoiesis in simple terms?

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

Why does Haematopoiesis matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Haematopoiesis?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Haematopoiesis.

Tags

  • Hematopoiesis
  • Histology

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