CHANGES IN UTERINE ENDOMETRIAL PHOSPHOLIPIDS AND FATTY-ACIDS THROUGHOUT THE ESTROUS-CYCLE AND EARLY-PREGNANCY IN THE EWE

This study examined changes in ovine endometrial phospholipids and fat ty acid concentrations associated with luteolysis and the establishmen t of pregnancy in the ewe on days 3, 12 and 15, respectively. Results from this study indicate that endometrial lipids increased as the oest rous cycle progressed from days 3 to 12 and 15, whereas during early p regnancy, endometrial lipids decreased on day 15 of pregnancy when com pared to days 3 and 12 of pregnancy. Phosphatidylcholine followed a si milar pattern to that of total lipids, with an increase in phosphatidy lcholine concentrations as the oestrous cycle progressed. During the e arly stages of pregnancy, phosphatidylcholine increased from day 3 to day 12, but then returned to previous levels by day 15 of pregnancy. P hosphatidylethanolamine increased late in the oestrous cycle, on day 1 5 as compared to days 3 and 12. This increase did not occur during ear ly pregnancy, with phosphatidylethanolamine concentrations being const ant from day 3 to day 15 of pregnancy. Both phosphatidylinositol and p hosphatidylserine followed a similar pattern to phosphatidylethanolami ne during the oestrous cycle and remained constant during early pregna ncy. The fatty acid content of the major phospholipids involved in pro staglandin synthesis were examined over the range of fatty acids from C14:0 to C24:1 omega 9. Although changes in arachidonic acid were obse rved, there were no clear indications that these changes were directly related to the changes in PGF(2 alpha) synthesis.