Question: Details on the origin and the pathogenesis of the so-called "ghost bodies" occurring in the arteries and arterioles following experimental lesions of the vascular wall were to be studied under peculiar experimental conditions (immunological injury and cholesterol diet in combination).
Material and methods: The experiments were carried out on 26 young rabbits of the same race and equal sex. They were selected from several test groups with experimentally induced arteriosclerosis. For challenge of immunological injury the animals were administered 3 intracutaneous injections of each 3 ml of horse serum at intervals of one week. Afterwards they received one or two intravenous injections of 2-3 ml of horse serum at weekly intervals. Immediately after the last injection the animals were sacrificed. A series of the animals were fed a cholesterol diet for some weeks after previous immunological injury (for details see WEIDENBACH and MASSMANN 1972). From a total of 26 animals always several sections of the aorta were investigated. 5 animals were used for controls. After decapitation of the animals the aortas were removed immediately and fixed in 2.5-3% glutaraldehyde for 2 hours. Afterwards they were postfixed in 1% osmium-Millonig solution for 1 hour. After 15 min the tissue samples were washed in Tyrode solution for 15 min, dehydrated in ascendent aceton grades and contrasted in blocks in the stage of 70% aceton. After embedding in Micropal the material was sectioned by an ultramicrotome OmU2 (Fa, Reichert, Wien) and investigated in electron microscopes of the types SEM 2-3 (100 kV) or KEM 1-2 (60 kV) (VEB Werk für Fernsehelektronik Berlin-Oberschöneweide).
Results: Basing on their observations the authors classify as ghost bodies all cytoplasmic protrusions and all constricted extracellular structures which are limited by a membrane and filled with prevailingly filamentous-granular material (figs. 1, 2, 3), occasionaly also including fragments of cell organelles (fig. 4). They develop from cytoplasmic protrusions or bulgings of the processes of smooth muscle cells (figs. 1 and 2). In these protrusions the cytoplasm of the smooth muscle cells is loosened and of filamentous-granular appearance (fig. 1). The cells themselves show all characteristics of a modified or activated smooth muscle cell: they are branched, the organelles display marked secretory-metabolic activity associated with partical loss of the contractile elements whereas degenerative changes of these cells are nearly completely absent. Frequently focal disorganization of the cell membrane with release of the content to extracellular regions can be observed which is locally associated with the development of fibrillar structures.--In the environment of the "ghost bodies" the formation of collagenous fibres is visible (fig. 3). Degenerative changes which point to transition to necrosis can only occasionally be observed...