ANHB2214 Lecture Notes - Lecture 7: Reticular Connective Tissue, Bone Marrow, Lymphoblast
26 Mar 2020
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What is a lymphocyte: leukocyte (white blood cell) agranulocytes lymphocytes, regulate and carry out adaptive immunity, second most numerous leukocyte in blood, small leukocyte, stem cells for all lymphocytes are in the red bone marrow . Can diffuse within areas of loose connective tissue. Hence forming secondary lymphoid organs: lymphocytes have prominent basophilic nuclei and very little cytoplasm, lymphoid tissue packed with such cells usually stains dark blue in hematoxylin and eosin (h&e) stained sections. Primary lymphoid organs: organs where immature lymphocytes acquire the receptors to recognise antigens. Thymus: flattened lymphoid organ, lymphatic nodules are absent here, located in anterior superior mediastinum, most active in childhood and decreases in size as age increases, slow involution from puberty middle age, thymic involution. Cellular proportion (thymocytes) decreases and adipose increases. Degenerative phenomenon: matures bone marrow-derived t cell precursors into immunocompetent t- lymphocytes, has vascularised connective tissue capsule. Dividing organ into many incompletely separated lobules: each lobule:
