Studies on the permeability of the blood-retinal barrier. I. On the existence, development, and site of a blood-retinal barrier.

THE concept of a blood-brain barrier has gradually evolved from a large number of different observations concerning the peculiar impermeability of the central nervous system to a wide range of substances. The original observations (Ehrlich, 1885) and much of the subsequent work (Goldmann, 1913; Spatz, 1933; Broman, 1949; Jeppsson, 1962; Bakay and Haque,' 1964; and many others) dealt with the behaviour of acid dyes, notably trypan blue which has been extensively used to demonstrate the presence or absence of this barrier.