All of my experiments were carried out with a uniform technic i. e., injection into the subarachnoid space with different kinds of fluids on healthy rabbits with normal hearing organs.In experiment No. 1, a dilute aquous solution of methylene blue was injected into the subarachnoid space, and observation was made on the fluid oozed out through the opening of the oval window, in order to find whether or not the solution would appear in the labyrinthine fluid. In this way, I found that the solution appeared in the labyrinthine fluid almost at the moment of injection, and knew a free communication existed between the cerebrospinal and the labyrinthine fluid.In experiment No. II, the cerebrospinal fluid, as well as the labyrinthine fluid was removed at definite times after the injection of an isotonic glucose solution or of Presojod into the subarachnoid space, and micro-chemical tests were done on these fluids for the injected solution (glucose or iodine). In this way, I found that glucose or iodine appeared in the labyrinthine fluid most markedly in about the minutes after its introduction into the subarachnoid space, its appearance became gradually less marked until it disappeared in about four hours, the solution thus introduced into the subarachnoid space (glucose or iodine) disappeared from the cerebrospinal fluid in about four hours, almost abreast of its disappearance from the labyrinthine fluid. From these facts, I further knew the communication between the cerebrospinal and the labyrinthine fluid to be very free, and the perilymph to be, at least, a part of the cerebrospinal fluid.In experiment No. III, by a through histological examination on a large number of the specimens of the petrous portions taken from the rabbits killed at different times after the injection of an Indian ink suspension or an isotonic ferrocyanide solution into the subarachnoid space, or after such an injection was accompanied by an artificial opening of a part of the labyrinthine cavity, the pathaways in the labyrinth of the said coloring fluid (Indian ink or a ferrocyanide solution) were studied very carefully. In this way, I could give, not only histological evidence for the results of experiments No. I and No. II, but also made out the facts summed up in the following.1. When a coloring fluid was injected into the subarachnoid space, it was transmitted immediately into the labyrinthine fluid, by way of the aquaeductus cochleae, However, (a) an Indian ink suspension was transmitted only to the perilymph, and not to the endolymph. (b) A ferrocyanide solution, a true solution, was transmitted not only to the perilymph, but to the endolymph. The transmission to the endolymph took place indirectly through the perilymph by a process of diffusion, which seemed to occur through the epithelium of the membraneous labyrinth, especially through that of the ligamentum spirale, the limbus spirale, the maculae acusticae, or the cristae ampullares.2. The pathways through which the coloring fluid injected into the subarachnoid space come into the labyrinth and out therefrom were.(a) At first, the fluid got into the scala tympani of the basal whorl of the cochlea through the aquaeductus cochleae, and ascended the scala tympani to the helicotrema, descended the scala vestibuli to the vestibular perilymphatic space, and from there reached all perilymphatic spaces of the semicircular canals on one side, and the surrounding of the saccus endolymphaticus along the outside of the aquaeductus vestibuli and the ductus endolymphaticus on the other side. A ferrocyanide solution was also transmitted, in part, to the endolomph by diffusion.(b) The fluid reaching the above parts was absorbed in the surrounding tissues and was carried out partly through the venous system, partly through the perivascular system and partly through the perineural lymph spaces of the acustic nerve.
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Jan 1, 2023
Naveena E + 4
Open Access