A simple method for the in vitro study of drug diffusion across ruminal epithelium is described. The characteristics of the
isolated membrane were defined by studies of ketone production from butyrate, histological studies, phenolsulphonthalein
penetration and permeability to pentobarbital, antipyrine and tetraethylammonium. The preparation was found to be
suitable for studies of less than 12 hours duration; after that time the integrity of the membrane as a barrier was lost due to
degenerative changes. The method had a primary advantage in that experimental variables could be rigorously controlled.
This article is based as part of a dissertation submitted by the senior author' to the graduate Faculty of the University of Missouri in partial fulfillment of the requirements for the degree of Doctor of Philosophy.