Luteal function in sheep injected with prostaglandin F2α directly into the corpus luteum

Groups of ewes received either saline or prostaglandin F_2α (PGF_2α) as an injection directly into the corpus luteum. Changes in circulating progesterone levels were measured as well as subsequent histological examination of the corpora lutea. Saline, or PGF_2α given at the two lower doses (60 and 120 μg respectively), failed to suppress progesterone levels permanently, or to induce degenerative changes in the corpora lutea. Treatment with a higher dose of PGF_2α (240 μg) was followed by a marked elevation in progesterone levels. These results are discussed in relation to reported effects of PGF_2α arriving at the ovary via the arterial circulation.