Development of red blood cells?

Red blood cells in human blood have no nucleus, which is formed by four times of mitosis of primitive red blood cells in bone marrow. The formation process of red blood cells is the development process from nucleated immature red blood cells to seedless reticulocytes and then to mature red blood cells. Development process: erythroid directed stem cells → erythrocytes → early erythrocytes → middle erythrocytes → late erythrocytes → reticulocytes → mature erythrocytes. In the development of red blood cells, embryonic red blood cells are initially produced by the yolk sac wall and released into the blood, which is nucleated red blood cells. Later, this nucleated red blood cell was replaced by different cell isotypes produced by liver nucleated red blood cells. In red blood cells, the inheritance of hemoglobin molecules from embryonic type, fetal type to adult type is necessary to adapt to environmental changes and combine and transport oxygen during development. White blood cells are produced by bone marrow. They gradually differentiated from precursor cells (stem cells) and matured into five main types: neutrophils, lymphocytes, monocytes, eosinophils and basophils. Under normal circumstances, the human body produces about 654.38+000 billion white blood cells every day. Produced by megakaryocytes in hematopoietic tissue of bone marrow. Multifunctional hematopoietic stem cells differentiate directionally in hematopoietic tissue, forming primitive megakaryocytes and then becoming mature megakaryocytes. Many depressions are formed on the cell membrane surface of mature megakaryocytes, which extend into the cytoplasm. The cell membranes of adjacent depressions fuse with each other in the deep part of the depression, so that part of the cytoplasm of megakaryocyte is separated from the mother. Finally, these components separated from the cytoplasm of megakaryocyte surrounded by cell membrane leave megakaryocyte, enter blood circulation through blood sinus in bone marrow hematopoietic tissue and become platelets. Hematopoietic stem cell transplantation can be divided into bone marrow transplantation, peripheral blood stem cell transplantation and umbilical cord blood stem cell transplantation according to the source of hematopoietic stem cells.