Ultrastructural aspects of and observations on the permeability of the rat mesentery to colloidal iron.

In works already published, it was made clear that many researches were interested in the absorption phenomena, permeability and structure of the visceral mesothelial tissue. Attention was concentrated on the mesentery and observations were made using the application of lanthanum nitrate and osmium-amine. The penetration of lanthanum nitrate is impeded by the basement membrane situated between the connective and mesothelial tissues. The heavy salt moves through and not between the mesothelial cells by passive diffusion. No reaction was observed in general with osmium-amine, with the exception of a few cases. In those instances, the osmium-amine reacted not only in the outer surface of the mesentery, but also penetrated with no visible reaction all the way to the connective tissue where it was detected in the elastic layer. In this paper, the colloidal iron was employed using different techniques, and depositions were detected in the surface of the mesentery, in the mesothelial cells and also in the connective tissue. A final conclusion that the permeability of different layers of tissues is of great variety and has a definite capacity for selectivity is suggested.