Three-dimensional observation of the vascular networks and functional proteins in the cochlear stria vascularis using a non-corroded casting method combined with an immunohistochemical analysis

Abstract

The corrosion casting method allows for the three-dimensional observations of capillary networks. However, a major disadvantage of this method is that it requires the removal of all tissues around the vasculature. In this study, we overcame this limitation by using a casting plastic resin (Mercox®) with fluorescence characteristics to visualize the capillary networks in the non-corroded cochlear stria vascularis of gerbils and rats. The capillary networks were imaged using confocal microscopy. Upon excitation with a 633 nm laser light, the fluorescent resin exhibited intense fluorescence, and optical sections through the specimens were used to construct three-dimensional images. Double labeling of strial functional proteins, including type IV collagen, facilitated glucose transporter 1 (GLUT1), and inward rectifying K⁺ channel 4.1 (Kir4.1), with the capillary lumen (visualized with the fluorescent resin) was used to determine the structural relationships in the stria vascularis. Confocal images revealed an intimate relationship between casted vessels and functional proteins in the stria vascularis. These observations indicate that a non-corroded casting method is useful for examining the three-dimensional vascular networks by confocal microscopy and can be combined with immunohistochemical studies to identify the structural characteristics of the associated vascular tissues.