Luteal function in sheep injected with prostaglandin F2alpha directly into the corpus luteum

Groups of ewes received either saline or prostaglandin F2alpha (PGF2alpha) 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 PGF2alpha given at the two lower doses (60 and 120 mug respectively), failed to suppress progesterone levels permanently, or to induce degenerative changes in the corpora lutea. Treatment with a higher dose of PGF2alpha (240 mug) was followed by a marked elevation in progesterone levels. These results are discussed in relation to reported effects of PGF2alpha arriving at the ovary via the arterial circulation.