Posted by Krishnapriya on Feb. 18, 2014, 4:42 p.m.
Bone marrow,the soft fatty tissue inside bone cavities is the source of all RBCs,platelets,WBCs.in adults the blood cells are formed mainly in the bone marrow of flat bones,such as shoulder bones,ribs,breast bone and pelvis.All the body cells are formed from a single type of cell called a STEM cell.Production of stem cells is controlled by many hormones including ''ERYTHROPOIETIN''(produced by kidney),THYROID hormones,CORTICAL STEROIDS and GROWTH HORMONE..................... The process of formation of red blood cells is called ERYTHROPOIESIS.the direct control of RBC production is exerted by a hormone called ERYTHROPOIETIN,which is secreted into blood by kidney &to a lesser extent,the liver.Erythropoietin is normally secreted in small amounts ,which stimulates the bone marrow to produce RBC at a rate adequate to replace the usual loss. TESTOSTERONE,the male hormone also stimulate the release of erythropoietin,which in turn promotes erythyropoiesis.this is the reason for higher number of RBC (5 million/cc)and higher concentration of haemoglobin (16 g/100ml)in males than in females.In female the number of RBC is 4.5 million/cc and cocentration of haemoglobin is 14g/100ml