Topic 36- Leucopoiesis – formation of granulocytes and agranulocytes
Covers granulopoiesis, describing the roughly 11-14 day maturation of granulocytes in bone marrow, the two-stage synthesis of azurophilic and then specific granules, and the stages from myeloblast through band cell to mature granulocyte. It then outlines monocyte development over about 55 hours, and lymphocyte origin in bone marrow with T cell maturation in the thymus and B cell formation.
Topic 36 of 59 in the MU Pleven syllabus for Cytology (Medicine, Year 1). The free AceMed note covers it in 4 sections, about 558 words (4 min of reading), with 28 flashcards.
In this note
Topic 36- Leucopoiesis – formation of granulocytes
Granulopoiesis
Agranulopoiesis
Lymphocytes
Granulopoiesis
• Differentiation and maturation take about 11-14 days
• Occurs in bone marrow
• Involves cytoplasmic changes dominated by synthesis of proteins for the azurophilic and specific granules. These proteins are produced in the RER and Golgi in two successive stages
• Azurophilic granules are made first and are generally the same in all 3 granulocytes. The Golgi then changes to produce proteins for the specific granules which differ for each granulocyte
• Stages of Granulopoiesis:
1. Myeloblast
2. Promyelocte
3. Neutrophil, eosinophil, basophil myelocyte
4. Neutrophil, eosinophil, basophil metamyelocyte
5. Band cell – only for neutrophilic granulocyte
6. Mature granulocyte
Stages explained
1. Myeloid cell has finely dispersed chromatin and faint nucleoli and no cytoplasmic granules
2. Promyelocyte has basophilic cytoplasm and azurophilic granules contain lysosomal enzymes. Different promyelocytes activate different sets of genes, resulting in lineages for the 3 types of granulocytes
3. Myelocyte stage, specific granules gradually increase
4. Specific granules eventually occupy most of the cytoplasm forming the metamyelocyte. The neutophilic, basophilic and eosinophilic metamyelocytes mature with further condensation of the nuclei
5. Before its complete maturation, the neutrophilic granulocyte passes through an intermediate stage, the band cell, in which the nucleus is elongated but not yet polymorphic.
Continue reading free
The whole note, all 4 sections, is free with an AceMed account, with its 28 flashcards. Premium adds flashcard recall, highlights and Ask AI.
