The final stages of cervical ripening and parturition resemble an inflammatory process. Although the role of cytokines in both spontaneous and experimentally induced parturitions has been described in several small laboratory animals and humans, the involvement of pro-inflammatory and regulatory cytokines in physiologic parturition in cows has not been determined. In this study, the cytokine expression profiles were assessed in bovine cervical tissue at several stages of pregnancy and at parturition. Serial biopsy samples of the cervix were obtained from 10 cows on day 185 and day 275 of pregnancy (which was on average 5.4 days before parturition) and at parturition. Messenger RNA expression levels of interleukin (IL)-1beta, IL-6, IL-8, IL-10 and tumour necrosis factor (TNF)alpha were determined using real-time polymerase chain reaction and the number of neutrophils and eosinophils was estimated by Luna and Sirius Red staining. At parturition, IL-8 expression had increased 430-fold (p < 0.001) when compared with that of the day 185 of pregnancy, large numbers of neutrophils had invaded the cervix while eosinophils remained scarce, IL-1beta had increased eightfold (p < 0.05) and IL-6 had not changed significantly. Additionally, IL-10 was increased by 10-fold (p < 0.001) and TNFalpha decreased by 57% (p < 0.05) when compared with that of the day 185 of pregnancy. The large increase in expression of IL-8, enabling the influx of neutrophils, is indicative of its important role in the final stage of cervical ripening and at parturition. As previous studies have shown that neutrophils excrete matrix metalloproteinases (MMP), this might contribute to softening of the cervix. In contrast, the only slightly increased levels of IL-1, steady concentrations of IL-6 and decreased TNFalpha, the potential consequences of increased IL-10 expression, indicate that final cervical of cows in ripening at term parturition is an inflammatory process influenced by regulatory cytokines.

No abstract

Collagen is denatured in the gradual cervical ripening process during late pregnancy, already before the onset of final cervical ripening at parturition. Matrix Metallo Proteinases (MMPs) might be responsible for this process. To investigate the presence and potential function of MMPs at the different stages of the ripening process, serial cervical biopsies were obtained from 10 cows at Days 185 and 275 of pregnancy (approximately 5 days before calving), at parturition and at 30 days after parturition. The mRNA and protein expression of MMP-1, MMP-2, and MMP-9 and of the tissue inhibitors of MMPs (TIMP)-1 and TIMP-2 were semi-quantitatively determined using RT-PCR, respectively, zymography, Westernblot, and ELISA techniques and the localization of MMP-2 protein and presence of granulocytes by immunohistochemistry and Luna staining. At parturition compared to 185 days pregnancy the MMP-1 protein expression and the numbers of granulocytes were significantly increased by 3 and 26-fold respectively. MMP-2 mRNA and protein expression had already increased 2.5 (P < 0.05) and twofold (P < 0.05) at 5 days before parturition, prior to final ripening. At that time, MMP-2 was present in smooth muscle cells and extra cellular matrix. TIMP-1 mRNA expression was significantly increased at parturition and TIMP-2 mRNA expression peaked at 5 days before parturition. The increased expression of MMP-2 at 5 days before parturition, suggests that in the cow MMP-2 is responsible for collagen denaturation in the last part of gradual cervical ripening, while MMP-1 and MMP-9 are only active during the final cervical ripening process at parturition.

The cervix must regain its normal diameter after parturition. Until now, little has been known about the pattern of cervical closure and the possible influences of myometrial and cervical contractions in this process. We continuously measured the cervical diameter with ultrasound cervimetry during the first 48 h after calving in six cows with retained fetal membranes, while uterine (n = 6) and cervical outer muscular layer (n = 4) electromyographic (EMG) activity was measured with bipolar EMG electrodes.We found that the cervical diameter which was 6.2 cm (AE0.7) at 1.4 h after calving, initially increased to 9.0 cm (AE1.0) during the first 14.8 h (AE2.8) postpartum. After this time, the diameter decreased gradually to 5.3 cm (AE1.0) at 48 h after calving. The overall EMG activity after parturition decreased by 59% (AE6) and 35% (AE17) for the uterus and cervix, respectively. The decrease in EMG activity was due to a 50% (AE7) decrease in EMG amplitudes of the myometrium; the EMG amplitudes of the cervix decreased by only 8% (AE21) (P > 0.05). At the same time in the cervix, burst frequency decreased by 69% (AE17), while the decrease in burst frequency of the myometrium was only 11% (AE5) (P > 0.05).Uterine myometrial and cervical EMG activity after parturition showed burst patterns. These contractions of the uterus and cervix were accompanied by and correlated with transient dilatations of the caudal cervix. This could have functional relevance in the evacuation of the uterus. #

The bovine cervix contains a large amount of smooth muscle cells distributed over an outer muscular layer and within a stromal layer. The stromal layer exhibits no electromyographic (EMG) activity at parturition. This leads to the question whether the stromal smooth muscle cells of the bovine cervix are prepared to contract with parturition, or whether they have another function. To this end, cervical biopsies were repeatedly taken from 10 pregnant cows at day-185 and -275 of gestation, at spontaneous, uncomplicated calving and at 30 days after calving. The smooth muscle bundles of the stroma were immunohistochemically analysed (n = 5) with regard to their integrity and cellular density, and the degree of staining for connexin-43, smooth muscle actin alpha (SMA), desmin and vimentin. Additionally, the mRNA expression for connexin-43, SMA, desmin and vimentin was determined with RT-PCR (n = 5). The smooth muscle tissue was arranged in bundles, also at parturition. However, the cellular density of these bundles and the SMA mRNA expression were decreased at parturition. Additionally, the SMA staining and connexin-43 expression and staining remained constant during pregnancy and at parturition. This might indicate that stromal smooth muscle cells are not prepared to contract with parturition, in contrast to the myometrial smooth muscle cells. The smooth muscle cells, stained for SMA, also expressed vimentin, and the proportion of co-expression was increased at day-275 of pregnancy. This suggests that the stromal smooth muscle cells predominantly have a secretory function in cows.