ML. Immunohistochemical localization of the interleukin-1 system in the mouse ovary during follicular growth, ovulation, and luteinization. Biol Reprod

The distribution of immunoreactive interleukin-l receptor type I (IL-IR tI), IL-la, and IL-IP, and of macrophages, was in-vestigated immunohistochemically in the mouse ovary during follicular growth, ovulation, and luteinization. For this purpose, an indirect immunofluorescence technique, using specific monoclonal antibodies against mouse IL-1R tI, mouse IL-la, IL-l0, and macrophage antigens (CDllb/CD18) was used with sections of paraffin-embedded ovaries from eCG and eCG/hCG-treated 12-wk-old B6C3F-1 female mice. During follicular development, IL-la, IL-1p, and IL-IR tI staining were confined to the theca-interstitial layer of growing follicles with one remarkable exception. Intense IL-1R tI staining was present in the cytoplasm and plasma membrane of the murine oocyte. During ovulation, IL-la and IL-IPi were still confined to the theca layer, but faint IL-1R tI staining was initiated in cumulus cells and in granulosa cells just before follicle rupture. Immediately after follicle rupture, granulosa cells stained positive for IL-IR tl, IL-la, and IL-1l. During luteinization, granulosa-luteal cells of the corpus luteum demonstrated strong IL-1R tI, IL-la, and IL-ll staining. Macrophages were detected in the theca layer and stroma, but never within the follicle before ovulation. Immediately after ovulation, there was a rapid entry of macrophages into the follicle, and macrophages were also present inside the corpus luteum. Our morphological results support a possible autocrine-paracrine role of the mouse ovarian IL-i system in ovulation and luteinization