When the cytoplasm becomes as acidophilic as that of a mature erythrocyte, the cells are known as ortho- chromatophilic erythroblasts or normoblasts, An orthochromatophilic erythroblast is only slightly larger than an erythrocyte. 4.0rthochromatophilic ErythroblastĮach polychromatophilic erythroblast undergoes a number of mitotic divisions with a gradual decrease in the basophilia and an increase in the amount of haemoglobin. Hence, these cells are named polychromatophilic erythroblasts.The nucleus of a polychromatophilic erythroblast shows a dense chromatin network with the coarse chromatin masses giving a characteristic checker-board appearance. With each mitotic division, there is a decrease in the basophilia of cytoplasm and an increase in the quantity of hemoglobin (which is acidophilic) Thus, the cytoplasm of these cells takes varying amounts of acid and basic components of the Wright stain and, therefore, shows mixed colours varying from purplish- blue to a light pink or grey. After undergoing a number of mitotic divisions, the proerythroblasts give rise to basophilic erythroblasts.īasophilic erythroblasts undergo a number of mitotic divisions and produce cells in which haemoglobin is present in sufficient quantities to be easily identified in stained smears. Some haemoglobin is present in the cytoplasm, but its amount is too small to be detected by ordinary staining techniques. The nucleus, which is spherical and centrally located, shows a uniform chromatin pattern and once or two large nucleoli. A proerythroblast is a very large cell (15-20 Hm in diameter) having a deeply basophilic cytoplasm. The CFU-E differentiates into a proerythroblast which is the earliest recognisable cell of the erythrocyte series. From CFU-E to mature RBC, the erythropoiesis comprises the following stages: Proerythroblast, basophilic erythroblast, polychromatophilic erythroblast, ortho- chromatophilic erythroblast, reticulocyte, and mature erythrocyte.
The erythrocytes are derived from the uni-potential progenitor cells called colony forming unit-erythrocyte (CFU-E), which themselves arise from CFU-GEMM. ERYTHROPOIESIS (DEVELOPMENT Of ERYTHROCYTES)
0 kommentar(er)
