Relationship between serum luteinizing hormone levels and the ability of porcine granulosa cells to luteinize and respond to exogenous luteinizing hormone in culture.

A group of 16 normally cycling pigs was subjected to bilateral ovariectomy at various times on the day before (day−1) and the day of estrus (day 0). Blood samples were assayed for LH by RIA. The granulosa cells were harvested from the large (6–12 mm), medium (3–5 mm), and small (1–2 mm) follicles of each pair of ovaries and cultured for 8 days in medium 199 plus 15% pig serum. Some of the granulosa cells were cultured in the presence of 1.0 μg/ml ovine LH. Progesterone was measured in the spent culture medium after 2, 4, 6, and 8 days. At the end of culture, the cultures were examined morphologically for luteinization after staining with oil Red 0 and hematoxalin. When LH levels were low (0.6–1.5 ng/ml) on day −1 of the estrous cycle, granulosa cells harvested from 6- to 7-mm follicles failed to luteinize morphologically in culture, exhibited a fibroblastic type morphology, and contained few lipid droplets. Their ability to secrete progesterone into the culture medium was poor. After 2, 4, and 6 days, the...