Phagocytotic activity of macrophages separated from corpus lutea of pseudopregnant rabbits

Macrophage activity as indicated by phagocytosis in the corpus luteum at the luteolysis stage was examined in rabbits during pseudopregnancy. The day of induction of pseudopregnancy was regarded as day 0, and the phagocytotic activity of macrophages obtained from luteal tissues was examined on days 7 and 16. When sheep red blood cells (SRBCs) were used to assess phagocytotic activity there was no difference in phagocytosis between days 7 and 16 but, when sensitized SRBCs were used to assess phagocytotic activity, the activity of macrophages on day 16 was more than double that on day 7 (P < 0.05). These results indicate that immunomediated phagocytosis of luteal macrophages is enhanced at the luteolysis stage (day 16). This phenomenon may contribute to the process of luteolysis.