Microsoft Word - NEF107BF.rtf

Summaries – Résumés Electron microscopic study of glomerular lesions resulting from intra-vascular fibrin formation By Vassalli, P.; Simon, C. and Rouiller, C.: Amer. J. Path. 43: 579-617 (1963). An electron microscopic study of glomerular alterations has been carried out in rabbits receiving injections of Liquoid, thromboplastin or thrombin. The major acute lesions consisted of swelling and proliferation of endothelial and intercapil-lary cells, heterophil infiltration, clumping of platelets and deposits of fibrin and fibrinoid. The granular osmiophilic material identified as fibrinoid was commonly seen between endothelium and the basement membrane. The topographic relationship of fibrinoid to fibrin and the transitional forms between these two substances indicated that fibrinoid was derived from fibrin. Phagocytosed fibrin was occasionally observed in the swollen endothelial and intercapillary cells. In addition to acute alterations, different stages in the development of progressive glomerular obliteration were seen. These exhibited various degrees of proliferation of intercapillary cells, accumulation of hyalin (basement membrane-like material) sometimes mixed with collagen fibrils, and various basement membrane alterations usually in the form of thickening. Formation of crescents was a less common feature. These changes sometimes ended in complete glomerular obliteration. The administration of epsilon-amino-caproic acid, a potent inhibitor of fibrino-lytic mechanism, together with Liquoid resulted in marked intensification of the glomerular lesions, especially of the fibrinoid deposits and the development of glomerular sclerosis. It is proposed that the intravascular formation of fibrin was the essential mechanism in the production of the glomerular abnormalities and could be an important mechanism of glomerular damage in other instances. Author’s address: Dr. Pierre Vassalli, New York University Medical Center, 550 First Avenue, New York, N.Y. (USA). The mesangium of the renal glomerulus By Suzuki, Y.; Churg, J.; Grishman, E.; Mautner, W. and Dachs, S.: Amer. J. Path. 43: 555-578 (1963). The mesangium of the renal glomerulus is a branching stalk of tissue which extends from the hilus into the peripheral lobules and provides support for the capillaries. The mesangium consists of cells and intercellular substance. The cells are characterized by numerous cytoplasmic processes and peripherally distributed fine fibrils 70-100 A in diameter. They have phagocytíc properties, they probably produce the intercellular substance and they bear some resemblance to smooth muscle cells. The intercellular substance is designated as mesangial matrix; it consists of fine fibrils embedded in a more homogeneous ground substance. It is similar to the basement membrane but is looser in structure and reacts differently to certain stimuli. The mesangium participates actively or passively in most of the diseases which affect the glomerulus. Inflammatory response in the glomerulus consists, to a great extent, of proliferation of mesangial cells. Glomerulosclerosis is due to increase in 108