tailieunhanh - Atlas of Clinical Hematology - part 2

Tế bào chất là agranular nhuộm panoptic bình thường, mặc dù các tế bào lớn tuổi thường xuyên cho thấy quá trình chuyển đổi hạt phôi thai có nghĩa giai đoạn promyelocyte (Hình 7 d). Các phản ứng peroxidase thường là tiêu cực, nhưng không có câu hỏi mà myeloblasts agranular | 36 Chapter IV Blood and Bone Marrow Fig. 6 e-h e f g h 37 IV 4 Individual Cells Fig. 6 i 38 Chapter IV Blood and Bone Marrow Granulocytopoiesis and Mast Cells Tissue Basophils Myeloblasts and Promyelocytes Fig. 7 a-h Myeloblasts are the earliest precursors of granu-locytopoiesis that can be identified by light microscopy. Today it is believed that they also function as precursors of monocytes . as myelomo-noblasts. They range from 12 to 20 pm in diameter Fig. 7a-c . The cytoplasmic rim is basophilic but may show a range of hues from soft pale blue to dark blue. The cytoplasm is agranular on ordinary panoptic staining although older cells frequently show incipient granulation signifying transition to the promyelocyte stage Fig. 7 d . The peroxidase reaction is usually negative but there is no question that agranular peroxidase-positive myeloblasts exist. The nucleus shows a very fine dense chromatin structure with as many as six nucleoli which generally are distinct and pale blue. Promyelocytes evolve directly from the myeloblasts by incorporating azurophilic granules into their cytoplasm in a concentric pattern surrounding the clear zone in the nuclear indentation Golgi zone which itself is devoid of granules. Initially there are few granules but these subsequently thicken and spread to fill the cytoplasm. At first the cytoplasm is basophilic but gradually lightens until it acquires the typical myelocytic tinge. The variable staining properties of the cytoplasm have led some authors to subdivide the promyelocytes into mature and immature forms groups I and II etc. As in myeloblasts the promyelocyte nucleus is finely structured and contains up to six nucleoli. The cells are peroxidase-positive. First to appear are the primary or azurophilic granule which contain peroxidase they are joined later by the specific secondary granules peroxidasenegative which increase as maturation proceeds. The cells are 20 - 25 pm in diameter making promyelocytes the largest .