Phagocytosis of cytoplasmic blebs derived from smooth muscle cells by fibroblast-like cells and macrophages in the post-partum rat uterus.
Numerous blebs were observed in contact with smooth muscle cells (SMC) by light microscopy in the myometrium of the rat uterus after parturition. Electron-microscopically the cell surface of SMC showed bulbous protrusions, which often lacked a basement membrane and were less electron-dense than the surrounding cytoplasm or sometimes nearly electron-lucent. Many bulbous protrusions were separated from SMC and became the isolated structures which we called cytoplasmic blebs. These bulbous protrusions and cytoplasmic blebs were often found to be phagocytosed by fibroblast-like cells and macrophages. A series of these tissue changes in the uterine myometrium after delivery, possibly due to hypoxic conditions, contribute to a rapid involution of SMC which have enlarged during pregnancy.
D000818:Animals; D001485:Basement Membrane / Q000648:ultrastructure; D005260:Female; D005347:Fibroblasts / Q000648:ultrastructure*; D008264:Macrophages / Q000648:ultrastructure*; D008854:Microscopy, Electron; D009130:Muscle, Smooth / Q000648:ultrastructure; D010587:Phagocytosis; D049590:Postpartum Period; D011247:Pregnancy; D051381:Rats; D011919:Rats, Inbred Strains; D014599:Uterus / Q000648:ultrastructure*