An analogous formula applies to the case of a continuous probability distribution. Not every probability distribution has a defined mean; see the Cauchy distribution for an example. Moreover, for some distributions the mean is infinite: for example, when the probability of the value is for n = 1, 2, 3, ....
Red blood cell (RBC) production (erythropoiesis) takes place in the bone marrow under the control of the hormone erythropoietin (EPO). Juxtaglomerular cells in the kidney produce EPO in response to decreased O 2 delivery (as in anemia and hypoxia) and increased levels of androgens.
The bone marrow of essentially all the bones produces red blood cells until a person is around five years old. The tibia and femur cease to be important sites of hematopoiesis by about age 25; the vertebrae, sternum, pelvis and ribs, and cranial bones continue to produce red blood cells throughout life.he following stages of development all occur within the bone marrow 1  : A Hemocytoblast, a multipotent hematopoietic stem cell, becomes. 2  a common myeloid progenitor or a multipotent stem cell, and then. 3  a unipotent stem cell, then. 4  a pronormoblast, also commonly called an proerythroblast or a rubriblast.