title: Distribution of Macromolecular Tracer Particles (Thorotrast(R)) in the Cochlea. An Electron Microscopic Study in Guinea Pig: Part I. The organ of Corti, the basilar membrane and the tympanic covering layer.
abstract: Thorotrast(R) containing thorium dioxide particles with diameters of around 100 Å was introduced in perilymph or endolymph using various methods and concentrations. The location of the tracer particles in the cochleas was determined using the transmission electron microscope. Injection of tracer into the cerebrospinal fluid (CSF) was considered to be the least unphysiological way to bring the tracer to the cochlea, and therefore most of the experiments were performed in that way. The distribution of tracer was very dependent on the mode of injection and the concentration of tracer in the cochlea. With very high concentrations it appeared that every kind of cell had a capacity of phagocytizing. No significant tracer uptake was noted in the cells of the organ of Corti after direct injection of small amounts of tracer in the cochlear duct. After tracer administration in the cerebrospinal fluid, the tracer rapidly reached the scala tympani. The tympanic border cells contained large numbers of tracer particles, while lesser amounts were found in the homogenous parts of the basilar membrane. No tracer was seen in the cells of the organ of Corti. After perfusion of the cochlear perilymph, some tracer was seen in the cells of the organ of Corti. The limited passage of tracer to the organ of Corti was not regarded as proof of free communication between perilymph and cortilymph. Glycerol administration to the animals did not change the propagation of tracer in the cochlea. After injection of tracer into dead animals, tracer inclusions could be seen in the tympanic border cells, indicating the possibility of a cell phagocytizing ability, also some time after death.
authors.forename: C
authors.initials: C
authors.lastname: Angelborg