Abstract
Concentrations of plasminogen activator in pia mater from pigs, horses, cows, monkeys, dogs, and rabbits were generally higher than recorded for any other organs in these animals. Great variations were encountered from species to species and between individuals, especially in pigs (95-4255 units/g fresh tissue) and dogs (810-4440 units). The concentration in dura mater was lower than that in pia.