title: Extravascular phagocytosis of proerythrocytes following 5-fluorouracil.
abstract: Amongst the perturbations induced in mouse bone marrow by 5-fluorouracil are the retention and phagocytosis of proerythrocytes within the extravascular compartment. Reasons for the latter response have been sought using electron microscopy. Proerythrocytes undergo normal maturation after 5-fluorouracil, judged by loss of mitochondria and vesicles, but fail generally to attain a biconcave shape. Most proerythrocytes have lost their organelles before phagocytosis occurs. Quantitative light microscopy shows a rise in the number of proerythrocytes 1 d after 5-fluorouracil which is attributable to maturation of orthochromatic erythroblasts. Thereafter the population size declines concomitantly with increased engulfment and phagocytosis by macrophages, activity which is maximal on days 4-5. Extravascular loss of proerythrocytes is also observed when marrow is rendered hypocellular by x-irradiation, or hydroxyurea. It is suggested that excessive maturation of proerythrocytes in the extravascular compartment can lead to their phagocytosis.
mesh_terms: D000818:Animals; D001853:Bone Marrow / Q000648:ultrastructure; D004900:Erythroblasts / Q000648:ultrastructure; D004912:Erythrocytes / Q000187:drug effects*; D005472:Fluorouracil / Q000494:pharmacology*; D008264:Macrophages / Q000648:ultrastructure; D008297:Male; D051379:Mice; D010587:Phagocytosis / Q000187:drug effects*
chemical_list: D005472:Fluorouracil