New Anatomical Aspects of the Vasculo-Epithelial Zone of the Spiral Limbus in Mammals

Abstract

The ultrastructure of the vasculo-epithelial zone of the spiral limbus of the guinea pig and cat is described. The vasculo-epithelial zone is composed of two types of cells osmiophilic (dark) and osmio-phobic (light) cells. The osmiophilic cells line the surface of the vasculo-epithelial zone and are bathed in perilymph. These cells have a dense cytoplasm and consist of numerous plasma membrane processes which are filled with tightly-packed mitochondria. Other cellular inclusions comprise an extensive network of endoplasmic reticulum and Golgi apparatus. The inferior layer consists of osmiophobic cells which contain endoplasmic reticulum and mitochondria. Morphologic similarities were noted among the vasculo-epithelial zone and other areas of the inner ear which are capable of active transport, e.g. the mammalian vestibular dark cells and the stria vascularis. The ultrastructural characteristics of the vasculo-epithelial zone suggest that this site is capable of active transport.

Notes

This research was supported in part by a grant from the John A. Hartford Foundation and in part by PHS grant NB 04627 from the National Institutes of Health.