| Abstract: | In this communication we report observations on the tight junctions of the frog choroid plexus obtained by thin section and freeze-fracture electron microscopy. It is shown that the choroid plexus epithelial tight junctions comprise a relatively high number (mean 5-6, range 3-10) of continuous, anastomosing strands. This is remarkable in relation to: (1) recent observations that the frog choroidal epithelium has a very low transepithelial resistance, and (2) current concepts of the proportional relationship between transepithelial resistance and number of tight junction strands. It is concluded that there exists a marked lack of correlation between tight junction structure and function in the frog choroid plexus epithelium. |
