Blood cell analyzer, blood cells derived from bone marrow hematopoietic pluripotent stem cells. In addition to the ability to proliferate, stem cells can still migrate from the bone marrow hematopoietic tissue under certain circumstances, and form hematopoietic cell nodules as the blood flow reaches the extramedullary tissue, which is called colony forming unit. Each small node is composed of many cells of the same type, which are derived from the division of a stem cell. Although stem cells have the ability to replicate and differentiate themselves into various blood cells, in general, they are not in a proliferative state, but in a resting G0 phase.
Blood Cell Analyzer Primitive stem cells can be differentiated into two branches: one is colony forming unit cells (CFU-C), also known as bone marrow stem cells, which are pluripotent stem cells of red blood cells, neutrophils, eosinophils and platelets. Colony-forming unit cells are mainly derived from bone marrow and go through the directional stem cell stage of each line before developing into erythrocytes, granulocytes and megakaryocytes. The other is lymphoid stem cells, also known as lymphoid stem cells, which are the birthplace of the immune system of higher animals. The process of differentiation and development is closely related to the stimulation of antigens. Lymphoid stem cells are also pluripotent stem cells, which can differentiate into two different directional stem cells. One is thymus-derived T lymphocytes or T cells, and the other is bone marrow-dependent B lymphocytes or B cells. These two cells are respectively transformed into primary lymphocytes and protoplasmic cells by restimulation of corresponding antigens, and then gradually mature and are respectively called lymphocytes and plasma cells.
In short, blood cells are derived from bone marrow hematopoietic pluripotent stem cells, which first differentiate from pluripotent stem cells into colony-forming unit cells (bone marrow stem cells) and lymphoid stem cells, and then differentiate from bone marrow stem cells into directional stem cells of various lines, which develop and proliferate into erythrocytes, granulocytes, monocytes and platelets through primitive and immature stages. Lymphoid stem cells are through the primitive, immature two stages, the development of proliferation and maturity; in the stimulation of antigen, and then transformed into the original lymphocytes and protoplasmic cells, and proliferation, maturation of lymphocytes and plasma cells with immune activity.
The proliferation of blood cells is carried out by division, but only immature cells have the ability to divide, once they mature to a certain stage. Proliferation will stop. There are two forms of general cell division:(1) mitosis (indirect division) during cell division, there are special filaments, so it is called mitosis. Mitosis is the main form of blood cell proliferation. Mitotic cells are not present in normal human circulating blood. The number of mitotic cells in hematopoietic tissues, reflecting the extent and state of their proliferation. The splitting process can be divided into four stages, mainly in the nuclear changes. ① Prophase (also known as monofilament ball stage): when cells begin to divide. The cell body becomes spherical, the nucleus swells, the nuclear chromatin aggregates into a single columnar chromosome, the nuclear membrane and the nucleosome disappear, and the shape is like a silk ball. Cytoplasmic staining becomes shallow, organelles and inclusions are temporarily hidden, and centrosome is shown. ② metaphase (also known as single stellate period): the centrosome begins to split, gradually to the poles, between which there are filaments, shaped like spindles, called spindles. The nuclear chromosomes are arranged in the middle of the spindle, like a star or chrysanthemum. ③ Late stage (also known as double stellate stage): Each chromosome is evenly divided into two, and the filament shrinks, so that the divided chromosomes tend to both ends of the cell with the centrosome and are arranged in two stellate. The cytoplasm begins to contract. ④ End stage (also known as silk ball stage): chromosomes tending to both ends of the cell begin to gather into silk ball, and then disperse into chromatin, forming small nuclei of two new nuclei. At this time, the cytoplasm can form dumbbell shape, and finally the cytoplasm separates and the cell divides into two.
(2) Amitosis (Direct Division) The manifestation of this division process is relatively simple. Usually, the nucleosome of the cell begins to separate first, then the surface of the nucleus shrinks, then gradually deepens and decomposes into two, followed by the separation of the cytoplasm, thus directly forming two daughter cells.