University:
Stanford University
Course:
MED 101 | Human Anatomy
Academic year:

2024
Views:

458

Pages:

1
Author:

larbi43100

‭Circulating element and its tissue corollary:‬ ‭ ononuclear phagocyte system.‬‭There are 3 compartments:‬‭a medullary where we find the‬ M ‭precursors, a blood compartment where we find the monocytes and when the monocytes migrate to‬ ‭the tissue level we have 3 compartments and there the monocytes are called macrophage. When we‬ ‭speak of mononuclear phagocytes we exclude from this system Langhéran cells, dendritic cells‬ ‭although these elements intervene like monocytes and macrophages in the expression of antigens to‬ ‭induce an immune response. You have to do this well distinction between antigen-presenting‬ ‭cells:Monocyte, macrophage, cell dendritic of myeloid origin whereas when we pass from the‬ ‭phagocyte system mononuclear cells we exclude dendritic cells, Langhéran cells since the‬ ‭precursors are not common with those of monocytes.‬ I‭ n MO of the monocyte:‬‭Makes 10 to 18 micrometers in‬‭diameter. The cytoplasm has irregular‬ ‭contours and is blue-gray (storm blue) in color. In this cytoplasm we can see azurophilic‬ ‭granulations which appear red in color on MGG; these granulations are relatively fine. The nucleus‬ ‭is in a central position, most often it has a polymorphic or horseshoe-shaped appearance. The‬ ‭chromatin has a combed appearance, quite fine but not as much as the precursors like myeloblast.‬ ‭Nuclear characters are important to differentiate these monocytes from large lymphocytes. The‬ ‭presence of a few intracytoplasmic vacuoles can allow differentiation between a monocyte and a‬ ‭large lymphocyte although intracytoplasmic vacuoles are most often seen on macrophages.‬ I‭ n ME:‬‭Numerous lysosomes are highlighted which correspond‬‭to azurophilic granulations. 2 types‬ ‭of granulations:‬ ‭1-‬ ‭Contains mainly myeloperoxidase, acid phosphatases.‬ ‭2-‬ ‭Which lacks them and which has different types of antigens and membrane markers. We can‬ ‭see cytoplasmic expansions: pseudopodes which will allow the ingestion of foreign particles.‬ ‭ ‬ ➔ ‭Cytochemical characteristics of monocytes‬‭:Peroxidases‬‭(myeloperoxidase) can‬ ‭be detected as in polynuclear neutrophils but the reaction is less intense. We can't highlight an‬ ‭esterase activity, it is the reaction of Naphthol ASD acetate which in the monocytic line is inhibited‬ ‭by sodium fluoride then that reaction is not inhibited by sodium fluoride in the neutrophil.‬ ‭✪What is this distinction for?‬ ‭ hen a patient presents with acute leukemia and the cells are very poorly differentiated and it is‬ W ‭difficult to tell if it is acute leukemia myeloblastic, monoblastic;we will help ourselves with these‬ ‭cytoc reactionshimiques to know if the circulating immature elements of this patient belong to the‬ ‭myeloid lineage or to the monocytic lineage. It helps to classify the type of acute leukemia but‬ ‭sometimes we cannot perfectly identify these immature elements.s and we use membrane antigens,‬ ‭clusters of differentiation (CD) and this detection of membrane antigens is ensured by a technique:‬ ‭flow cytometry.‬