Licht-und elektronenoptische Untersuchungen an der Membrana limitans gliae superficialis und der Leptomeninx im Rückenmark des Schweines*

Abstract

Summary Light and electron microscopical examinations on the membrana limitans gliae superficialis and the leptomeninx of the spinal cord of the pig. The membrana limitans gliae superficialis of the pig varies in thickness and consists mainly of processes of fiber‐rich astrocytes which, apart from normal mitochondria, contain giant mitochondria up to 7.5 μm in size. On the surface of the membrana limitans is a continuous basement membrane. The pia mater spinalis is fibrous. There are mainly collagenous fibers, but also elastic fibers, microfibrils, fibroblasts, fibrocytes, macrophages, blood vessels and bundles of nerve fibers. The structure of the arachnoid is by and large similar to that of other mammals. The subarachnoid space is lined with a continuous layer of mesothelial cells which in the region of the pia has a discontinuous basement membrane. The mesothelial cells may contain membranous vesicles and have desmosomes and nexus connections. No gaps and pores were observed in this cell layer, and it is thought that this layer prevents direct contact between cerebrospinal fluid and the connective tissue of the leptomeninx. On the basis of structural findings, literature and our own examinations, the problems of cerebrospinal fluid resorption are discussed.

Subdural compartment in pig: A morphologic study with blood and horseradish peroxidase infused subdurally

“…In well-preserved, perfusion-fixed material, obtainable only in experimental animals, the subdural cells appear densely packed and more electron-lucent than the arachnoid cells (Fiedler and Drommer, 1976;Andres, 1967;Himango and Low, 1971;Oda and Nakanishi, 1984; present study). They are darker in animals perfused with high concentrations of glutaraldehyde (Waggener and Beggs, 1967,6.2%) known to cause tissue shrinkage.…”

“…In pig it is regularly distinguishable deep to the arachnoid barrier layer of the cerebral meninges. Judged by previously published illustrations it is present also at spinal levels in pig (Fiedler and Drommer, 1976) as well enlarged in C, is bleeding into the perineural sheaths (arrows), in one fascicle (asterisk) also into the endoneurium. The lateral pocket of the blood-containing SDC is indicated by a white asterisk, the dentate ligament by an open star.…”

“…The structure of the meninges has been described in numerous studies of animals (Pease and Schultz, 1958;Andres, 1967;Waggener and Beggs, 1967;Klika, 1967;McCabe and Low, 1969;Himango and Low;1971;Akashi, 1972;Allen and Low, 1975;Fiedler and Drommer, 1976;Allen and DiDio, 1977;Nabeshima et al, 1975;Oda and Nakanishi, 1984) and humans (Key and Retzius, 1876;Anderson, 1969;Lopes and Mair, 1974;Rascol and Izard, 1976;Schachenmayr and Friede, 1978;Alcolado et al, 1988). There is no general agreement, however, regarding definition, ultrastructure, and function of the dura-arachnoid junction, i.e., the meningeal layer referred to by Nabeshima et al (1975) as the "dural border layer," but tentatively identified here as the "subdural compartment" (SDC).…”

“…The cellular tissue forming what we call the SDC has been shown electron microscopically to be directly contiguous with the stratified perineural sheaths of the spinal nerve roots (Andres, 1967;McCabe and Low, 1969;Himango and Low, 1971;Fiedler and Drommer, 1976). Although a flow of cerebrospinal fluid from the subarachnoid space (SAS) along the spinal nerves has been documented (e.g., Klatzo et al, 1964), we have found no paper testing the possibility of a drainage from the SDC along this route.…”

“…It is appropriate also from a technical, economical, and ethical point of view. An ultrastructural examination of normal pigs, however, proved necessary because of the shortage of reports on the structure of the meninges in this species (Fiedler and Drommer, 1976;Klika and Richter, 1989). Fifteen years after Nabeshima et al 's (1975) comprehensive electron microscopic study of the meninges in smaller mammals, we take advantage of the "historical gain" and use their summary diagram as a starting point in our results.…”