NEET BIOLOGY

Detailed explanation-1: -During embryonic stages, red blood cells are produced in the liver and spleen. In young children (up to about 5 years of age), red blood cells are produced in the bone marrow of all bones. In adults, the RBCs are produced in the marrow of long bones such as the ribs, breastbone, and ilium.

Detailed explanation-2: -The fetal liver is the site of development of adult-type red blood cells, which mature within “erythroblastic islands” (EBIs).

Detailed explanation-3: -Later in embryonic life, the liver becomes the most important red blood cell-forming organ, but it is soon succeeded by the bone marrow, which in adult life is the only source of both red blood cells and the granulocytes.

Detailed explanation-4: -During foetal life, the liver plays the important roles of connection and transient hematopoietic function. Foetal liver cells develop in an environment called a hematopoietic stem cell niche composed of several cell types, where stem cells can proliferate and give rise to mature blood cells.

Detailed explanation-5: -Final answer: Erythropoiesis starts in the Red bone marrow.