Luteolysis and Thrombus Formation in Ovaries of Immature Superstimulated Golden Hamsters

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Abstract
Thrombus appearance during luteolysis with and without exogenous prostaglandin (PGF2.alpha.) was studied in immature golden hamsters between days 4 and 7 after stimulation with pregnant mares'' serum gonadotrophin (PMSG) followed by human chorionic gonadotrophin. Both ovaries were weighed and cut in series for light-microscopic evaluation. The fibrinolytic activity was determined by the fibrin slide method after treatment with PGF2.alpha. on day 4 after PMSG stimulation and compared with controls of days 3 and 4 after PMSG stimulation. There was a marked decrease in ovarian weights in the experimental and the control group between days 4 and 7 after PMSG. Few necrotic cells were seen in corpora lutea on day 5, but many on day 6. All of them had disappeared on day 7. The number of ovaries with thrombi was 80-100% in both groups on day 4 and declined to approximately zero levels on day 7. The amount of thrombus formation appeared to be higher in the PGF2.alpha.-treated groups than in controls. Fibrinolytic activity was high in controls on day 3 and low in controls and in PGF2.alpha.-treated animals on day 4 after PMSG. It is concluded that (i) thrombus formation occurs in superstimulated ovaries during luteolysis; and (ii) thrombus formation is related to a decrease in fibrinolytic activity.