The mononuclear phagocytes of the rat adrenal.

Structural and functional investigations have revealed the presence of a population of mononuclear phagocytes in the sinusoids of the rat adrenal. These phagocytes were of myelogenous origin, while electron microscopy and peroxidase cytochemistry demonstrated characteristics resembling those of monocytes. Their concentration on the sinus wall increased after systemic zymosan treatment, due to a transient selective margination of circulating monocytes, many of which were in the synthetic phase of the cell cycle. The monocytic margination in the zymosan-treated rats shown to be partly due to changes in the sinus wall and partly dependent on the surface properties of circulating monocytes.