Culture of bovine preantral follicles in a serum-free system: Markers for assessment of growth and development

Satisfactory development of bovine follicles in vitro remains elusive. This study used a serum-free system to evaluate the effects of insulin-like gro wth factor-1 (IGF-1) on bovine preantral follicles in culture and to identi fy the activity of gelatinase matrix metalloproteinases (MMPs) and their en dogenous inhibitors (TIMPs) in vitro to assess their potential as markers o f development. Preantral follicles were cultured for 6 days in serum-free m edium containing insulin and IGF-1 (10 ng/ml). No difference was observed i n follicular growth, health, or antrum formation between IGF-1-treated foll icles and controls. However, IGF-1 had a negative effect (P < 0.01) on oocy te size and granulosa cell proliferation. When MMP-9 was secreted, the prob ability of follicles having healthy granulosa or theca cells at the end of the culture period was 0.85 and 0.60, respectively. If TIMP-1 was released, the probability of follicles having healthy somatic cells was 0.79. When T IMP-2 was detected, the probability of granulosa and theca cell health was 0.78 and 0.67, respectively. These results demonstrate no positive effects of IGF-1 on bovine follicles in this system. Furthermore, MMP-9 and TIMPs a re related to follicular health and, therefore, can be used as markers of f ollicular development.