Key points are not available for this paper at this time.
The barrier between blood and brain was discovered in 1913, when it was believed that the BBB was localized to the choroid plexus, and that nutrient flow from blood passed through the CSF en route to brain. These misconceptions are still widely held, and hinder progress in the development of technology for BBB drug delivery.
William M. Pardridge (2016) studied this question.