Bone marrow in the context of "Bone marrow transplant"

A bone is a rigid organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the organs of the body, produce red and white blood cells, store minerals, help regulate acid-base homeostasis, provide structure and support for the body, and enable mobility and hearing. Bones come in a variety of shapes and sizes and have complex internal and external structures.

Bone tissue (also known as osseous tissue or bone in the uncountable) is a form of hard tissue, specialised connective tissue that is mineralized and has an intercellular honeycomb-like matrix, which helps to give the bone rigidity. Bone tissue is made up of different types of bone cells: osteoblasts and osteocytes (bone formation and mineralisation); osteoclasts (bone resorption); modified or flattened osteoblasts (lining cells that form a protective layer on the bone surface). The mineralised matrix of bone tissue has an organic component of mainly ossein, a form of collagen, and an inorganic component of bone mineral, made up of various salts. Bone tissue comprises cortical bone and cancellous bone, although bones may also contain other kinds of tissue including bone marrow, endosteum, periosteum, nerves, blood vessels, and cartilage.

Typhoid fever, also known as typhoid, is a disease caused by Salmonella enterica serotype Typhi bacteria, also called Salmonella typhi. Symptoms vary from mild to severe, and usually begin six to 30 days after exposure. Often there is a gradual onset of a high fever over several days. This is commonly accompanied by weakness, abdominal pain, constipation, headaches, and mild vomiting. Some people develop a skin rash with rose colored spots. In severe cases, people may experience confusion. Without treatment, symptoms may last weeks or months. Diarrhea may be severe, but is uncommon. Other people may carry it without being affected, but are still contagious. Typhoid fever is a type of enteric fever, along with paratyphoid fever. Salmonella enterica Typhi is believed to infect and replicate only within humans.

Typhoid is caused by the bacterium Salmonella enterica subsp. enterica serovar Typhi growing in the intestines, Peyer's patches, mesenteric lymph nodes, spleen, liver, gallbladder, bone marrow and blood. Typhoid is spread by eating or drinking food or water contaminated with the feces of an infected person. Risk factors include limited access to clean drinking water and poor sanitation. Those who have not yet been exposed to it and ingest contaminated drinking water or food are most at risk for developing symptoms. Only humans can be infected; there are no known animal reservoirs. Salmonella typhi which causes typhoid fever is different from the other Salmonella bacteria that usually cause salmonellosis, a common type of food poisoning.

Hematopathology or hemopathology (both also spelled haem-, see spelling differences) is the study of diseases and disorders affecting and found in blood cells, their production, and any organs and tissues involved in hematopoiesis, such as bone marrow, the spleen, and the thymus. Diagnoses and treatment of diseases such as leukemia and lymphoma often deal with hematopathology; techniques and technologies include flow cytometry studies and immunohistochemistry.

In the United States, hematopathology is a board-certified subspecialty by the American Board of Pathology. Board-eligible or board-certified hematopathologists are usually pathology residents (anatomic, clinical, or combined) who have completed hematopathology fellowship training after their pathology residency. The hematopathology fellowship lasts either one or two years. A physician who practices hematopathology is called a hematopathologist.

In oncology, polycythemia vera (PV) is an uncommon myeloproliferative neoplasm in which the bone marrow makes too many red blood cells. Approximately 98% of PV patients have a JAK2 gene mutation in their blood-forming cells (compared with 0.1-0.2% of the general population).

Most of the health concerns associated with PV, such as thrombosis, are caused by the blood being thicker as a result of the increased red blood cells.

White blood cells (scientific name leukocytes), also called immune cells or immunocytes, are cells of the immune system that are involved in protecting the body against both infectious disease and foreign entities. White blood cells are generally larger than red blood cells. They include three main subtypes: granulocytes, lymphocytes and monocytes.

All white blood cells are produced and derived from multipotent cells in the bone marrow known as hematopoietic stem cells. Leukocytes are found throughout the body, including the blood and lymphatic system. All white blood cells have nuclei, which distinguishes them from the other blood cells, the anucleated red blood cells (RBCs) and platelets. The different white blood cells are usually classified by cell lineage (myeloid cells or lymphoid cells). White blood cells are part of the body's immune system. They help the body fight infection and other diseases. Types of white blood cells are granulocytes (neutrophils, eosinophils, and basophils), and agranulocytes (monocytes, and lymphocytes (T cells and B cells)). Myeloid cells (myelocytes) include neutrophils, eosinophils, mast cells, basophils, and monocytes. Monocytes are further subdivided into dendritic cells and macrophages. Monocytes, macrophages, and neutrophils are phagocytic. Lymphoid cells (lymphocytes) include T cells (subdivided into helper T cells, memory T cells, cytotoxic T cells), B cells (subdivided into plasma cells and memory B cells), and natural killer cells. Historically, white blood cells were classified by their physical characteristics (granulocytes and agranulocytes), but this classification system is less frequently used now. Produced in the bone marrow, white blood cells defend the body against infections and disease. An excess of white blood cells is usually due to infection or inflammation. Less commonly, a high white blood cell count could indicate certain blood cancers or bone marrow disorders.

Platelets or thrombocytes (from Ancient Greek θρόμβος (thrómbos) 'clot' and κύτος (kútos) 'cell') are a part of blood whose function (along with the coagulation factors) is to react to bleeding from blood vessel injury by clumping to form a blood clot. Platelets have no cell nucleus; they are fragments of cytoplasm from megakaryocytes which reside in bone marrow or lung tissue, and then enter the circulation. Platelets are found only in mammals, whereas in other vertebrates (e.g. birds, amphibians), thrombocytes circulate as intact mononuclear cells.

One major function of platelets is to contribute to hemostasis: the process of stopping bleeding at the site where the lining of vessels (endothelium) has been interrupted. Platelets gather at the site and, unless the interruption is physically too large, they plug it. First, platelets attach to substances outside the interrupted endothelium: adhesion. Second, they change shape, turn on receptors and secrete chemical messengers: activation. Third, they connect to each other through receptor bridges: aggregation. Formation of this platelet plug (primary hemostasis) is associated with activation of the coagulation cascade, with resultant fibrin deposition and linking (secondary hemostasis). These processes may overlap: the spectrum is from a predominantly platelet plug, or "white clot" to a predominantly fibrin, or "red clot" or the more typical mixture. Berridge adds retraction and platelet inhibition as fourth and fifth steps, while others would add a sixth step, wound repair. Platelets participate in both innate and adaptive intravascular immune responses.