IMMUNOLOGY

Detailed explanation-1: -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 erythropoietin in response to decreased oxygen delivery (as in anemia or hypoxia) or increased levels of androgens.

Detailed explanation-2: -Erythropoietin (EPO) is a hormone that is produced predominantly by specialised cells called interstitial cells in the kidney. Once it is made, it acts on red blood cells to protect them against destruction. At the same time it stimulates stem cells of the bone marrow to increase the production of red blood cells.