Immune regulation of ovarian function in buffaloes (Bubalus bubalus)

We studied the infiltration of different subsets of immune system cells in the ovarian parenchyma of Egyptian buffaloes during follicular and luteal p hases of the estrous cycle All subsets of leukocytes infiltrated significan tly more into corpora lutea (CL) than into Graafian follicles (GF) (P < 0.0 1) except for plasma cells that were abundant in the GF but not observed in the CL. The number of macrophages, lymphocytes, neutrophils and eosinophil s were significantly greater in mature CL than in corpora hemorrhagica (CH) or regressing CL. Moreover, the regressing CL showed significantly more ma crophages, lymphocytes and neutrophils than the CH. Large antral follicles were infiltrated with larger number of leukocytes than growing preantral at retic follicles. Macrophages and neutrophils observed in large antral folli cles were significantly more abundant in the theca externa than the theca i nterna (P < 0.01). Only plasma cells were significantly greater in number i n the theca interna (P < 0.01). Leukocytes infiltrated significantly more i nto large mature follicles than large, growing, preantral atretic follicles (P < 0.01). Results of this study reveal the calling of leukocytes in a si gnificant numbers inside the ovarian tissue of buffaloes around the lime of ovulation and at luteolysis. It is possible that leukocytes with their pow erful bioactive cytokines (IL-1, TNF alpha, GM-CSF, and INF-gamma) may assi st in ovarian functions such as ovulation and luteolysis. (C) 2001 by Elsev ier Science Inc.