Thrombopoiesis is the process of thrombocyte generation.Thromobocytes are ligations of the cytoplasm from megakaryocytes. A single megakaryocyte can give rise to thousands of thrombocytes.
In cell biology, the cytoplasm is all of the material within a cell, enclosed by the cell membrane, except for the cell nucleus. The material inside the nucleus and contained within the nuclear membrane is termed the nucleoplasm. The main components of the cytoplasm are cytosol – a gel-like substance, the organelles – the cell's internal sub-structures, and various cytoplasmic inclusions. The cytoplasm is about 80% water and usually colorless.
The term "thrombocytopoiesis" is sometimes used to emphasize the cellular nature.
Thrombopoietin stimulates megakaryopoiesis, the process of megakaryocyte maturation and differentiation. Thrombopoietin, upon release, binds to its receptor, c-mpl, found on megakaryocyte progenitor cells. Following binding, intracellular signalling leads to megakaryocyte growth, maturation, membrane stability, platelet granule formation and the demarcation of the cytoplasm into regions destined to fragment into mature platelets. These "proplatelet processes" further fragment into platelets. This last step of proplatelet process and platelet formation, in vitro, has been shown to be independent of thrombopoietin.
Thrombopoietin (THPO) also known as megakaryocyte growth and development factor (MGDF) is a protein that in humans is encoded by the THPO gene.
A megakaryocyte is a large bone marrow cell with a lobated nucleus responsible for the production of blood thrombocytes (platelets), which are necessary for normal blood clotting. Megakaryocytes usually account for 1 out of 10,000 bone marrow cells in normal people, but can increase in number nearly 10-fold during the course of certain diseases. Owing to variations in combining forms and spelling, synonyms include megalokaryocyte and megacaryocyte.
The term cell growth is used in the contexts of biological cell development and cell division (reproduction). When used in the context of cell development, the term refers to increase in cytoplasmic and organelle volume, as well as increase in genetic material following the replication during S phase.growth|. This is not to be confused with growth in the context of cell division, referred to as proliferation, where a cell, known as the "mother cell", grows and divides to produce two "daughter cells".
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;
Platelets, also called thrombocytes, are a component of blood whose function is to react to bleeding from blood vessel injury by clumping, thereby initiating a blood clot. Platelets have no cell nucleus: they are fragments of cytoplasm that are derived from the megakaryocytes of the bone marrow, and then enter the circulation. Circulating unactivated platelets are biconvex discoid (lens-shaped) structures, 2–3 µm in greatest diameter. Platelets are found only in mammals, whereas in other animals thrombocytes circulate as intact mononuclear cells.
Immune thrombocytopenia (ITP) is a type of thrombocytopenic purpura defined as isolated low platelet count (thrombocytopenia) with normal bone marrow and the absence of other causes of thrombocytopenia. It causes a characteristic purpuric rash and an increased tendency to bleed. Two distinct clinical syndromes manifest as an acute condition in children and a chronic condition in adults. The acute form often follows an infection and has a spontaneous resolution within two months. Chronic immune thrombocytopenia persists longer than six months with a specific cause being unknown.
Thrombocytopenia is a condition characterized by abnormally low levels of thrombocytes, also known as platelets, in the blood.
Primary myelofibrosis is a relatively rare bone marrow cancer. It is currently classified as a myeloproliferative neoplasm, in which the proliferation of an abnormal clone of hematopoietic stem cells in the bone marrow and other sites results in fibrosis, or the replacement of the marrow with scar tissue.
GATA-binding factor 1 or GATA-1 is the founding member of the GATA family of transcription factors. This protein is widely expressed throughout vertebrate species. In humans and mice, it is encoded by the GATA1 and Gata1 genes, respectively. These genes are located on the X chromosome in both species.
Beta-thromboglobulin is a protein that is stored in alpha-granules of platelets and released in large amounts after platelet activation.
A promegakaryocyte is a precursor cell for a megakaryocyte, arising from a megakaryoblast.
Gray platelet syndrome (GPS), or platelet alpha-granule deficiency, is a rare congenital autosomal recessive bleeding disorder caused by a reduction or absence of alpha-granules in blood platelets, and the release of proteins normally contained in these granules into the marrow, causing myelofibrosis.
Thrombopoietic agents are drugs that induce the growth and maturation of megakaryocytes. Some of them are currently in clinical use: romiplostim, eltrombopag, oprelvekin and thrombopoietin. Several others are under clinical investigation such as lusutrombopag and avatrombopag.
Platelet membrane glycoproteins are surface glycoproteins found on platelets (thrombocytes) which play a key role in hemostasis. When the blood vessel wall is damaged, platelet membrane glycoproteins interact with the extracellular matrix.
Eltrombopag is a medication that has been developed for certain conditions that lead to thrombocytopenia. It is a small molecule agonist of the c-mpl (TpoR) receptor, which is the physiological target of the hormone thrombopoietin. Eltrombopag was discovered as a result of research collaboration between GlaxoSmithKline and Ligand Pharmaceuticals. Designated an orphan drug in the United States and European Union, it is being manufactured and marketed by Novartis under the trade name Promacta in the USA and is marketed as Revolade in the EU. Novartis acquired the drug as a part of its asset swap deal with GlaxoSmithKline.
The Harrington–Hollingsworth experiment was an experiment that established the autoimmune nature of the blood disorder immune thrombocytopenic purpura. It was performed in 1950 by the academic staff of Barnes-Jewish Hospital in St. Louis, Missouri.
The thrombopoietin receptor also known as the myeloproliferative leukemia protein or CD110 is a protein that in humans is encoded by the MPL oncogene.
Romiplostim is a fusion protein analog of thrombopoietin, a hormone that regulates platelet production.
CFU-Meg is a colony forming unit. Haematopoiesis in the bone marrow starts off from a haematopoietic stem cell (HSC) and this can differentiate into the myeloid and lymphoid cell lineages. In order to eventually produce a megakaryocyte, the haematopoietic stem cell must generate myeloid cells, so it becomes a common myeloid progenitor, CFU-GEMM. This in turn develops into CFU-Meg, which is the colony forming unit that leads to the production of megakaryocytes.
Congenital amegakaryocytic thrombocytopenia (CAMT) is a rare inherited disorder.
The nuclear-cytoplasmic ratio is a measurement used in cell biology. It is a ratio of the size of the nucleus of a cell to the size of the cytoplasm of that cell.
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