An electron microscopic study on the blood-optic nerve and fluid-optic nerve barriers using horseradish peroxidase as a tracer.

Abstract

The purpose of the present study is to investigate peroxidase diffusion processes in the optic nerve of albino mice with light and electron microscopes in order to elucidate the blood-optic nerve and fluid optic-nerve barriers.
Mice were given intravenous injection of 3mg horseradish peroxidase (HRP) in 0.5m1 of isotonic saline or intraventricular (the lateral ventricle of the brain) injection of 0.12∼0.15 mg HRP in 0.02∼0.03 ml of isotonic saline. After mice were sacrificed, Graham-Karnovsky method (1966) was used to demonstrate the localization of HRP. In addition, isotonic saline, same doses as described above, was injected into the same places as controls. Subsequently the routine method for electron microscopy was followed. Epon sections ( 1∼1.5/μ) stained with toluidine blue solution and reacted frozen sections (10∼30/μ) were observed with light microscope. Ultrathin sections were stained with lead and uranyl or with uranyl only. Some of thin sections were observed without stain. In some cases, uranyl en bloc staining was applied.