Ethyl-oxide effects on a newly formed blood-brain barrier.

The morphofunctional effects of ethyl-oxide, utilized as anaesthetic, on the optic tectum blood-brain barrier were investigated in hatching chick embryos (21st incubation day) and young chickens in which the barrier to the marker of vascular permeability horseradish peroxidase is complete after the 18th incubation day. Results indicate that ethyl-oxide administration produces horseradish peroxidase extravasation by opening the tight interendothelial junctions. The escape rate of the marker is higher in the tecta of hatching embryos than in those of chickens and in both horseradish peroxidase extravascular diffusion is more frequent at the level of vessel bifurcation than along the branchless vessel tracts.