Reminder on the Content of the Granulations

‭Reminder on the content of the granulations‬ ‭ here are granulation peroxidases with the defense that may or may not be present in them.‬ T ‭Warning: We can talk about gelatinase granules positively in that they will have a content mainly in‬ ‭gelatinase but that does not mean that in the specific granules we cannot highlight “a little bit” of‬ ‭gelatinase. The acquisition of granulations is done in a well-determined order following the‬ ‭different stages of maturation and the last to be acquired are the secretory vesicles while at the start‬ ‭we have the granulations which are without defensin with simply peroxidase, then there is‬ ‭appearance of defensin and all this depends on the expression of different genes.‬ ‭ egakaryocytic lineage.‬ M ‭Aims to generate thrombocytes or platelets. One of the characteristics is the phenomenon of‬ ‭endoreplication, that is to say that there is duplication of DNA and mitosis will not be not finalized‬ ‭by cyto dieresis which is the fragmentation into two cells so we have an element which becomes‬ ‭polyploid.‬ ‭Diagram: On the left we have a normal mitosis with the spindle, the chromosomes, a separation‬ ‭identical sister chromatids while at the level of endomitosis of the megakaryocyte we also have a‬ ‭correct separation of sister chromatids but there are spindle anomalies which induce a somewhat‬ ‭random distribution of sister chromatids by contribution to centrioles, this means that the final stage‬ ‭of mitosis: cyto dieresis does not take place.‬ ‭- 1 highlighted element is the megakaryoblast:It is a cell which is large in size between 30 and 100‬ ‭micrometers, the size is variable depending on the degree of endoreplication. Endoreplication can‬ ‭make it possible to have a DNA Q of up to 64n and we only consider that there is a possibility of‬ ‭maturation to give a thrombocytopenic megakaryocyte when it There was an endoreplication‬ ‭allowing 8n content, therefore 4 times more than normal. At this point we have a megakaryocyte‬ ‭which can become thrombocytopenic. The megakaryoblast is a basophilic cell, with coarse‬ ‭chromatin, which will give rise to a basophilic megakaryocyte without division (because of‬ ‭endoreplication).‬ -‭ ‬ ‭This basophilic megakaryocyte has‬‭very blue cytoplasm‬‭at MGG. Appearance of‬ ‭azurophilic granulations which subsequently correspond to the granulomer (which we see in the‬ ‭platelets). There is no more nucleolus. Then we have a:‬ ‭-‬ ‭Granular megakaryocyte‬‭:where the granulations are‬‭very important in the cytoplasm. The‬ ‭cytoplasm becomes slightly acidophilic and the granulations give a purplish appearance to the‬ ‭cytoplasm. The granular megakaryocyte becomes a:‬ ‭-‬ ‭Thrombocytopenic megakaryocyte‬‭:Nuclear indentations‬‭or notches are‬ ‭important. In the cytoplasm we distinguish 3 zones:‬ ‭❖‬ ‭a perinuclear where‬‭we find mitochondria, ribosomes.‬ ‭❖‬ ‭intermediate majority zone where‬‭evidence of packets‬‭of granulations delimited by‬ ‭membranes, we speak of demarcation membranes and this corresponds to future platelets.‬ ‭❖‬ ‭The 3rd area is just under the cytoplasmic membrane‬‭;here‬‭we find a few ribosomes, a‬ ‭few microfibrils, and microtubules. The demarcat ion membranes have 2 origins:the Golgi‬ ‭apparatus and cytoplasmic invaginations and in fact there is contact between the exterior of the cell‬ ‭and the demarcation membranes which are inside which go delimit the territory of the platelets.‬