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Bone marrow
Bone marrow is a semi-solid tissue which may be found within the spongy or cancellous portions of bones . In birds and mammals , bone marrow is the primary site of new blood cell production or hematopoiesis . It is composed of hematopoietic cells , marrow adipose tissue , and supportive stromal cells . On average , bone marrow constitutes 4 % of the total body mass of humans ; in an adult having 65 kilograms of mass ( 143 lb ) , bone marrow typically accounts for approximately 2.6 kilograms ( 5.7 lb ) . Human marrow produces approximately 500 billion blood cells per day , which join the systemic circulation via permeable vasculature sinusoids within the medullary cavity . All types of hematopoietic cells , including both myeloid and lymphoid lineages , are created in bone marrow ; however , lymphoid cells must migrate to other lymphoid organs ( e.g. thymus ) in order to complete maturation .
Bone marrow
Bone marrow examination is the pathologic analysis of samples of bone marrow obtained via biopsy and bone marrow aspiration . Bone marrow examination is used in the diagnosis of a number of conditions , including leukemia , multiple myeloma , anemia , and pancytopenia . The bone marrow produces the cellular elements of the blood , including platelets , red blood cells and white blood cells . While much information can be gleaned by testing the blood itself ( drawn from a vein by phlebotomy ) , it is sometimes necessary to examine the source of the blood cells in the bone marrow to obtain more information on hematopoiesis ; this is the role of bone marrow aspiration and biopsy .
Human musculoskeletal system
Located in long bones are two distinctions of bone marrow ( yellow and red ) . The yellow marrow has fatty connective tissue and is found in the marrow cavity . During starvation , the body uses the fat in yellow marrow for energy . The red marrow of some bones is an important site for blood cell production , approximately 2.6 million red blood cells per second in order to replace existing cells that have been destroyed by the liver . Here all erythrocytes , platelets , and most leukocytes form in adults . From the red marrow , erythrocytes , platelets , and leukocytes migrate to the blood to do their special tasks .
Bone marrow
The composition of marrow is dynamic , as the mixture of cellular and non-cellular components ( connective tissue ) shifts with age and in response to systemic factors . In humans , marrow is colloquially characterized as `` red '' or `` yellow '' marrow ( Latin : medulla ossium rubra , Latin : medulla ossium flava , respectively ) depending on the prevalence of hematopoetic cells vs fat cells . While the precise mechanisms underlying marrow regulation are not understood , compositional changes occur according to stereotypical patterns . For example , a newborn baby 's bones exclusively contain hematopoietically active `` red '' marrow , and there is a progressive conversion towards `` yellow '' marrow with age . In adults , red marrow is found mainly in the central skeleton , such as the pelvis , sternum , cranium , ribs , vertebrae and scapulae , and variably found in the proximal epiphyseal ends of long bones such as the femur and humerus . In circumstances of chronic hypoxia , the body can convert yellow marrow back to red marrow to increase blood cell production .
Bone marrow
In a bone marrow transplant , hematopoietic stem cells are removed from a person and infused into another person ( allogenic ) or into the same person at a later time ( autologous ) . If the donor and recipient are compatible , these infused cells will then travel to the bone marrow and initiate blood cell production . Transplantation from one person to another is conducted for the treatment of severe bone marrow diseases , such as congenital defects , autoimmune diseases or malignancies . The patient 's own marrow is first killed off with drugs or radiation , and then the new stem cells are introduced . Before radiation therapy or chemotherapy in cases of cancer , some of the patient 's hematopoietic stem cells are sometimes harvested and later infused back when the therapy is finished to restore the immune system .
Bone marrow
Another option is to administer certain drugs that stimulate the release of stem cells from the bone marrow into circulating blood . An intravenous catheter is inserted into the donor 's arm , and the stem cells are then filtered out of the blood . This procedure is similar to that used in blood or platelet donation . In adults , bone marrow may also be taken from the sternum , while the tibia is often used when taking samples from infants . In newborns , stem cells may be retrieved from the umbilical cord .
Bone marrow
Bone marrow transplants can be conducted to treat severe diseases of the bone marrow , including certain forms of cancer such as leukemia . Additionally , bone marrow stem cells have been successfully transformed into functional neural cells , and can also potentially be used to treat illnesses such as inflammatory bowel disease .
Bone marrow
The red bone marrow is a key element of the lymphatic system , being one of the primary lymphoid organs that generate lymphocytes from immature hematopoietic progenitor cells . The bone marrow and thymus constitute the primary lymphoid tissues involved in the production and early selection of lymphocytes . Furthermore , bone marrow performs a valve - like function to prevent the backflow of lymphatic fluid in the lymphatic system .
Bone marrow
Biological compartmentalization is evident within the bone marrow , in that certain cell types tend to aggregate in specific areas . For instance , erythrocytes , macrophages , and their precursors tend to gather around blood vessels , while granulocytes gather at the borders of the bone marrow .
Bone marrow
At the cellular level , the main functional component of bone marrow includes the progenitor cells which are destined to mature into blood and lymphoid cells . Marrow contains hematopoietic stem cells which give rise to the three classes of blood cells that are found in circulation : white blood cells ( leukocytes ) , red blood cells ( erythrocytes ) , and platelets ( thrombocytes ) .
Bone marrow
To diagnose diseases involving the bone marrow , a bone marrow aspiration is sometimes performed . This typically involves using a hollow needle to acquire a sample of red bone marrow from the crest of the ilium under general or local anesthesia .
Bone marrow
Bone marrow stem cells can be induced to become neural cells to treat neurological illnesses , and can also potentially be used for the treatment of other illnesses , such as inflammatory bowel disease . In 2013 , following a clinical trial , scientists proposed that bone marrow transplantation could be used to treat HIV in conjunction with antiretroviral drugs ; however , it was later found that HIV remained in the bodies of the test subjects . Harvesting
Bone marrow
The stroma of the bone marrow includes all tissue not directly involved in the marrow 's primary function of hematopoiesis . Stromal cells may be indirectly involved in hematopoiesis , providing a microenvironment that influences the function and differentiation of hematopoeietic cells . For instance , they generate colony stimulating factors , which have a significant effect on hematopoiesis . Cell types that constitute the bone marrow stroma include :
Bone marrow
Medical imaging may provide a limited amount of information regarding bone marrow . Plain film x-rays pass through soft tissues such as marrow and do not provide visualization , although any changes in the structure of the associated bone may be detected . CT imaging has somewhat better capacity for assessing the marrow cavity of bones , although with low sensitivity and specificity . For example , normal fatty `` yellow '' marrow in adult long bones is of low density ( - 30 to - 100 Hounsfield units ) , between subcutaneous fat and soft tissue . Tissue with increased cellular composition , such as normal `` red '' marrow or cancer cells within the medullary cavity will measure variably higher in density .
Stem cell
Pluripotent adult stem cells are rare and generally small in number , but they can be found in umbilical cord blood and other tissues . Bone marrow is a rich source of adult stem cells , which have been used in treating several conditions including liver cirrhosis , chronic limb ischemia and endstage heart failure . The quantity of bone marrow stem cells declines with age and is greater in males than females during reproductive years . Much adult stem cell research to date has aimed to characterize their potency and self - renewal capabilities . DNA damage accumulates with age in both stem cells and the cells that comprise the stem cell environment . This accumulation is considered to be responsible , at least in part , for increasing stem cell dysfunction with aging ( see DNA damage theory of aging ) .
Bone marrow
The earliest fossilised evidence of bone marrow was discovered in 2014 in Eusthenopteron , a lobe - finned fish which lived during the Devonian period approximately 370 million years ago . Scientists from Uppsala University and the European Synchrotron Radiation Facility used X-ray synchrotron microtomography to study the fossilised interior of the skeleton 's humerus , finding organised tubular structures akin to modern vertebrate bone marrow . Eusthenopteron is closely related to the early tetrapods , which ultimately evolved into the land - dwelling mammals and lizards of the present day .
Bone marrow
The normal bone marrow architecture can be damaged or displaced by aplastic anemia , malignancies such as multiple myeloma , or infections such as tuberculosis , leading to a decrease in the production of blood cells and blood platelets . The bone marrow can also be affected by various forms of leukemia , which attacks its hematologic progenitor cells . Furthermore , exposure to radiation or chemotherapy will kill many of the rapidly dividing cells of the bone marrow , and will therefore result in a depressed immune system . Many of the symptoms of radiation poisoning are due to damage sustained by the bone marrow cells .
Bone marrow
The bone marrow stroma contains mesenchymal stem cells ( MSCs ) , also known as marrow stromal cells . These are multipotent stem cells that can differentiate into a variety of cell types . MSCs have been shown to differentiate , in vitro or in vivo , into osteoblasts , chondrocytes , myocytes , marrow adipocytes and beta - pancreatic islets cells .
Bone marrow
MRI is more sensitive and specific for assessing bone bone composition . MRI enables assessment of the average molecular composition of soft tissues , and thus provides information regarding the relative fat content of marrow . In adult humans , `` yellow '' fatty marrow is the dominant tissue in bones , particularly in the ( peripheral ) appendicular skeleton . Because fat molecules have a high T1 - relaxivity , T1 - weighted imaging sequences show `` yellow '' fatty marrow as bright ( hyperintense ) . Furthermore , normal fatty marrow loses signal on fat - saturation sequences , in a similar pattern to subcutaneous fat .
Bone marrow
fibroblasts ( reticular connective tissue ) macrophages , which contribute especially to red blood cell production , as they deliver iron for hemoglobin production . adipocytes ( fat cells ) osteoblasts ( synthesize bone ) osteoclasts ( resorb bone ) endothelial cells , which form the sinusoids . These derive from endothelial stem cells , which are also present in the bone marrow .
Bone marrow
The blood vessels of the bone marrow constitute a barrier , inhibiting immature blood cells from leaving the marrow . Only mature blood cells contain the membrane proteins , such as aquaporin and glycophorin , that are required to attach to and pass the blood vessel endothelium . Hematopoietic stem cells may also cross the bone marrow barrier , and may thus be harvested from blood .
Bone marrow
Bone Marrow Details System Immune system ( Lymphatic system ) ( Endocrine system ) Identifiers Latin Medulla ossium MeSH D001853 TA A13. 1.01. 001 FMA 9608 Anatomical terminology ( edit on Wikidata )
Bone marrow
Animal bone marrow has been used in cuisine worldwide for millennia , such as the famed Milanese Ossobuco .
White blood cell
White blood cells ( WBCs ) , also called leukocytes or leucocytes , are the cells of the immune system that are involved in protecting the body against both infectious disease and foreign invaders . 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 .
Stem cell
In practice , stem cells are identified by whether they can regenerate tissue . For example , the defining test for bone marrow or hematopoietic stem cells ( HSCs ) is the ability to transplant the cells and save an individual without HSCs . This demonstrates that the cells can produce new blood cells over a long term . It should also be possible to isolate stem cells from the transplanted individual , which can themselves be transplanted into another individual without HSCs , demonstrating that the stem cell was able to self - renew .
Stem cell
Stem cell therapy is the use of stem cells to treat or prevent a disease or condition . Bone marrow transplant is a form of stem cell therapy that has been used for many years without controversy . No stem cell therapies other than bone marrow transplant are widely used .
Stem cell
Adult stem cells , also called somatic ( from Greek σωματικóς , `` of the body '' ) stem cells , are stem cells which maintain and repair the tissue in which they are found . They can be found in children , as well as adults .
Stem cell
Bone marrow , which requires extraction by harvesting , that is , drilling into bone ( typically the femur or iliac crest ) . Adipose tissue ( fat cells ) , which requires extraction by liposuction. ( citation needed ) Blood , which requires extraction through apheresis , wherein blood is drawn from the donor ( similar to a blood donation ) , and passed through a machine that extracts the stem cells and returns other portions of the blood to the donor .
Bone marrow
The stem cells are typically harvested directly from the red marrow in the iliac crest , often under general anesthesia . The procedure is minimally invasive and does not require stitches afterwards . Depending on the donor 's health and reaction to the procedure , the actual harvesting can be an outpatient procedure , or can require 1 -- 2 days of recovery in the hospital .
Bone marrow
When `` yellow '' fatty marrow becomes replaced by tissue with more cellular composition , this change is apparent as decreased brightness on T1 - weighted sequences . Both normal `` red '' marrow and pathologic marrow lesions ( such as cancer ) are darker than `` yellow '' marrow on T1 - weight sequences , although can often be distinguished by comparison with the MR signal intensity of adjacent soft tissues . Normal `` red '' marrow is typically equivalent or brighter than skeletal muscle or intervertebral disc on T1 - weighted sequences .
Heart
The heart is a muscular organ in most animals , which pumps blood through the blood vessels of the circulatory system . Blood provides the body with oxygen and nutrients , as well as assists in the removal of metabolic wastes . In humans , the heart is located between the lungs , in the middle compartment of the chest .
Stem cell
Adult stem cell treatments have been successfully used for many years to treat leukemia and related bone / blood cancers through bone marrow transplants . Adult stem cells are also used in veterinary medicine to treat tendon and ligament injuries in horses .
White blood cell
Some leucocytes migrate into the tissues of the body to take up a permanent residence at that location rather than remaining in the blood . Often these cells have specific names depending upon which tissue they settle in , such as fixed macrophages in the liver , which become known as Kupffer cells . These cells still serve a role in the immune system .
Stem cell
Stem cells are biological cells that can differentiate into other types of cells and can divide to produce more of the same type of stem cells . They are found in multicellular organisms .
Phosphorus cycle
The primary biological importance of phosphates is as a component of nucleotides , which serve as energy storage within cells ( ATP ) or when linked together , form the nucleic acids DNA and RNA . The double helix of our DNA is only possible because of the phosphate ester bridge that binds the helix . Besides making biomolecules , phosphorus is also found in bone and the enamel of mammalian teeth , whose strength is derived from calcium phosphate in the form of Hydroxylapatite . It is also found in the exoskeleton of insects , and phospholipids ( found in all biological membranes ) . It also functions as a buffering agent in maintaining acid base homeostasis in the human body .
White blood cell
The name `` white blood cell '' derives from the physical appearance of a blood sample after centrifugation . White cells are found in the buff , a thin , typically white layer of nucleated cells between the sedimented red blood cells and the blood plasma . The scientific term leukocyte directly reflects its description . It is derived from the Greek roots leuk - meaning `` white '' and cyt - meaning `` cell '' . The buffy coat may sometimes be green if there are large amounts of neutrophils in the sample , due to the heme - containing enzyme myeloperoxidase that they produce .
Human musculoskeletal system
The skeletal system serves as a framework for tissues and organs to attach themselves to . This system acts as a protective structure for vital organs . Major examples of this are the brain being protected by the skull and the lungs being protected by the rib cage .
Stem cell
In mammals , there are two broad types of stem cells : embryonic stem cells , which are isolated from the inner cell mass of blastocysts , and adult stem cells , which are found in various tissues . In adult organisms , stem cells and progenitor cells act as a repair system for the body , replenishing adult tissues . In a developing embryo , stem cells can differentiate into all the specialized cells -- ectoderm , endoderm and mesoderm ( see induced pluripotent stem cells ) -- but also maintain the normal turnover of regenerative organs , such as blood , skin , or intestinal tissues .
Human musculoskeletal system
Another function of bones is the storage of certain minerals . Calcium and phosphorus are among the main minerals being stored . The importance of this storage `` device '' helps to regulate mineral balance in the bloodstream . When the fluctuation of minerals is high , these minerals are stored in bone ; when it is low it will be withdrawn from the bone .
Bone marrow
The ratio between myeloid series and erythroid cells is relevant to bone marrow function , and also to diseases of the bone marrow and peripheral blood , such as leukemia and anemia . The normal myeloid - to - erythroid ratio is around 3 : 1 ; this ratio may increase in myelogenous leukemias , decrease in polycythemias , and reverse in cases of thalassemia .
Nutrition and cognition
This vitamin is important for the facilitation of glucose use , thus ensuring the production of energy for the brain , and normal functioning of the nervous system , muscles and heart . Thiamine is found throughout mammalian nervous tissue , including the brain and spinal cord . Metabolism and coenzyme function of the vitamin suggest a distinctive function for thiamine within the nervous system . The brain retains its thiamine content in the face of a vitamin - deficient diet with great tenacity , as it is the last of all nervous tissues studied to become depleted .
Megaloblastic anemia
Bone marrow ( not normally checked in a patient suspected of megaloblastic anemia ) shows megaloblastic hyperplasia .
Stem cell
Multipotent stem cells are also found in amniotic fluid . These stem cells are very active , expand extensively without feeders and are not tumorigenic . Amniotic stem cells are multipotent and can differentiate in cells of adipogenic , osteogenic , myogenic , endothelial , hepatic and also neuronal lines . Amniotic stem cells are a topic of active research .
Spinal cord
The spinal cord is a long , thin , tubular bundle of nervous tissue and support cells that extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column . The brain and spinal cord together make up the central nervous system ( CNS ) . In humans , the spinal cord begins at the occipital bone where it passes through the foramen magnum , and meets and enters the spinal canal at the beginning of the cervical vertebrae . The spinal cord extends down to between the first and second lumbar vertebrae where it ends . The enclosing bony vertebral column protects the relatively shorter spinal cord . It is around 45 cm ( 18 in ) in men and around 43 cm ( 17 in ) long in women . Also , the spinal cord has a varying width , ranging from 13 mm ( ⁄ in ) thick in the cervical and lumbar regions to 6.4 mm ( ⁄ in ) thick in the thoracic area .
White blood cell
An increase in the number of white blood cells in circulation is called leukocytosis . This increase is most commonly caused by inflammation . There are four major causes : increase of production in bone marrow , increased release from storage in bone marrow , decreased attachment to veins and arteries , decreased uptake by tissues . Leukocytosis may affect one or more cell lines and can be neutrophilic , eosinophilic , basophilic , monocytosis , or lymphocytosis . Neutrophilia
Cremation
The ash remaining represents very roughly 3.5 % of the body 's original mass ( 2.5 % in children ) . Because the weight of dry bone fragments is so closely connected to skeletal mass , their weight varies greatly from person to person . Because many changes in body composition ( such as fat and muscle loss or gain ) do not affect the weight of cremated remains , the weight of the remains can be more closely predicted from the person 's height and sex ( which predicts skeletal weight ) , than it can be predicted from the person 's simple weight .
Bone marrow
Fatty marrow change , the inverse of red marrow hyperplasia , can occur with normal aging , though it can also be seen with certain treatments such as radiation therapy . Diffuse marrow T1 hypointensity without contrast enhancement or cortical discontinuity suggests red marrow conversion or myelofibrosis . Falsely normal marrow on T1 can be seen with diffuse multiple myeloma or leukemic infiltration when the water to fat ratio is not sufficiently altered , as may be seen with lower grade tumors or earlier in the disease process .
Thymus
The thymus is a specialized primary lymphoid organ of the immune system . Within the thymus , T cells mature . T cells are critical to the adaptive immune system , where the body adapts specifically to foreign invaders . The thymus is composed of two identical lobes and is located anatomically in the anterior superior mediastinum , in front of the heart and behind the sternum . Histologically , each lobe of the thymus can be divided into a central medulla and a peripheral cortex which is surrounded by an outer capsule . The cortex and medulla play different roles in the development of T cells . Cells in the thymus can be divided into thymic stromal cells and cells of hematopoietic origin ( derived from bone marrow resident hematopoietic stem cells ) . Developing T cells are referred to as thymocytes and are of hematopoietic origin . Stromal cells include epithelial cells of the thymic cortex and medulla , and dendritic cells .