| The healthy pregnant sheep and conceptus at the periods of 80~85d, 100~105d ,120~125d, 135~140d of gestation and parturition were used. The jugular blood, amnion fluid, cotyledon, caruncle, intercotyledon and intercamncle tissues and cervix (n=5, respectively) were collected .The apoptosis, the changes of microscopic structure and ultrastructure of the placenta and cervix were examine; The levels of IL-1 , IL-6, TNF- , fibronectin, NO, E2 and E3, and to matrix metalloproteinase (MMP2, and 9) were determined to study the maturity of the placenta and cervix of the pregnant ewes.. The results showed as followed :1.Morphology of conceptus: the diameter of the largest placentome at the periods of 80--85d and 100~105d of gestation was significantly larger than that at other stages of gestation(P<0.01 or, P<0.001).The average diameter of the largest placentome at 80~85d of gestation was 10.76 0.72cm, and then it decreased gradually. After 120~125d of gestation, it become stable, which indicated the ripening of placenta.Although the volume of amnion fluid and allantotic fluid increased markedly with advancement of pregnancy , it had most practical significance that the ratio of two fluids changed at different pregnant stages. The ratio of amnion fluid and allantotic fluid was 3.85 at 80~85d, 1.22 at 100~105d, and 0.82 at 120~125d of gestation, the ratio became stable at 135~140d and parturition (0.97 and 1.01), which indicated that the placenta had ripened.The change in length , diameter and texture of cervix in sheep showed that the length of cervix increased gradually ,diameter of cervix was always small and texture of cervix was always rigid at 80d to 120d of gestation. At 135~140d of gestation, the length decreased, its diameter widened and texture softened. At parturition, the diameter was widest, texture was softest, but length increased a little.2.Apoptosis of placenta: It was not found that apoptosis of cellular trophoblast and endothelial cell occurred, but apoptosis of syncytial trophoblast often occurred, and the number and percentage of apoptosis in the cells increased gradually with advancing pregnancy. The number of apoptosis cells reached to the maximal level at parturition. The change of apoptosis in cervix was similar to one in placenta, but the primary apoptotic cell in cervix were fibroblast, and there appeared lipofuscin body at from 135~140d of gestation, which meant that apoptosis would occur.3 As compared with that in control group, the level of IL-1 and EL-6 only at 120~125dof gestation was higher (P<0.01), but the levels of TNF- at all stages of gestation were higher (P<0.01). With advancing pregnancy, the levels of three cellular factors in sera in sheep increased gradually and reached to maximal level at 120~125d of gestation(2.348±0397ng/ml, 579.8±152.8pg/ml and 0.390±0.196ng/ml respectively), and then decreased a little at 135-140d, finally started to increase at parturition, which suggested that TNF- a could have an important part in setup of parturition.4As compared with level(2.7±1.04 mol/L) in control group, there were higher level of NO in sera in sheep at from 80d to 140d of gestation(>13.8±7.21 mol/L)(P<0.01), and the level started to decrease markedly at parturition and reached to4.9±1.29 p mol/L .The change curve in level of NO in amnion fluid was similar to one in sera, and the level of NO in amnion fluid at each stage of gestation was a little lower than that in sera, which suggested that NO would have an important part in maintaining gestation.5.With advancing pregnancy, the level of fibronectin in amnion fluid in sheep decreased gradually, and the rapid decrease ocurred at 135~140d of gestation. As compared with level of fibronectin at 80d, 100d and 120d of gestation, the content of fibroncctin at 140d was lower (P <0.01). At parturition, the content decreased to 1.75±0.83 g/ml, which reflected the extent of tight junction between maternal and fetal membrane. The low content meant that there appeared loose junction between two mem... |
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