COCHLEAR STRUCTURE AS REVEALED BY FREEZE-FRACTURING AND ULTRAHISTOCHEMISTRY FOR MUCOSUBSTANCE

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  • Freeze-Fracture法•組織化学法による蝸牛の電顕的観察
  • Freeze-Fracture法・組織化学法による蝸牛の電顕的観察--アミノ配糖体系抗生物質による聴器障害理解のために
  • Freeze Fractureホウ ソシキ カガクホウ ニヨル カタツムリ ノ
  • IN RELATION TO OTOTOXICITY OF AMINOGLYCOSIDE ANTIBIOTICS

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The fine structure of the membranous cochlea of the guinea pigs was observed using freeze- fracture technique and ultrahistochmical techniques of ruthenium red(RR) staining and of periodic acid methenamine silver(PAM) impregnation in addition to conventional light micro-scopic observation.<br>The freeze-fracturing revealed clearly intercellular junctions, pinocytic vesicles and memb-rane particles besides the structures obtained by conventional method of ultrathin sectioning.RR staining and PAM impregnation, which detect principally acidic glycosaminoglicans and glycoprotein respectively, revealed surface cell coat(glycocalyx), ground substance, collagen fibers and others.The obtained results were as follows.<br>1) The membranous cochlea had vast extracellular space and the organ of Corti was as if "floating" in it.This phenomenon was discussed in relation to the vulneability of the hair cell to aminoglycoside antibiotics.<br>2) The intercellular spaces of the organ of Corti, filled with cortilymph, were strictly sealed towards the endolymph by the "very tight junction"(Claude, P.et al., 1973) at the level of the reticular membrane.Thus the ototoxic substance of large molecule such as aminogly-coside antibiotics may gain access to the hair cell only from the perilymph.<br>3) The characteristic findings of the hair cell with thick glycocalyx covering the cell membrane, the periodically arranged particles on the membrane and subsurface cisterna beneath it were discussed to be related possibly to the electrical excitability and/or vulneability to amino-glycoside antibiotics.<br>4) Spiral ligament possessed abundant acidic glycosaminoglicans and/or glycoprotein among spiral ligament cells which were regarded as fibroblasts.The administration of aminoglycoside antibiotics may decrease these substances and the retention of such antibiotics in perilymph seemed to be subsequently prolonged.

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