Tight junction structure in relation to transepithelial resistance in the frog choroid plexus

Area of Science:

• Cell Biology
• Physiology
• Microscopy

Background:

• Tight junctions form barriers in epithelial tissues.
• Transepithelial electrical resistance (TER) typically correlates with tight junction strand number.
• The frog choroid plexus epithelium exhibits unusually low TER.

Purpose of the Study:

• To investigate the structure of tight junctions in the frog choroid plexus epithelium.
• To correlate tight junction morphology with observed transepithelial electrical resistance.

Main Methods:

• Thin section electron microscopy.
• Freeze-fracture electron microscopy.

Main Results:

• Frog choroid plexus epithelial tight junctions possess a high number of continuous, anastomosing strands (mean 5-6, range 3-10).
• This structural observation contrasts with the known low transepithelial resistance of this tissue.

Conclusions:

• There is a significant lack of correlation between tight junction strand number and transepithelial electrical resistance in the frog choroid plexus.
• Current models relating tight junction structure to barrier function may require revision for certain epithelia.