Department of Veterinary Clinical Sciences, The Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Hertfordshire AL9 7TA, UK.
Reproduction. 2010 Jul;140(1):133-41. doi: 10.1530/REP-09-0424. Epub 2010 Apr 22.
The complex anatomy of the ovine cervix limits the success of trans-cervical artificial insemination in sheep. However, there is a degree of natural relaxation of cervix at oestrus that is accompanied by an increase in the water content. As hyaluronan (HA) has a high affinity for water molecules, in this study, we tested the hypothesis that the HA content of the cervix, the proportion of different size fragments of HA and expression of its receptor CD44 vary with the stage of the oestrous cycle. Oestrous was synchronized in 25 Welsh mountain ewes, and their cervices were collected either during luteal phase (n=8) or pre-LH (n=8) or post-LH (n=9) surge stage of the oestrous cycle. The pre-LH surge group had the highest HA content (2.96 ng/mg of cervical tissue), which was significantly (P<or=0.05) higher than that observed for the post-LH surge (2.04 ng/mg) group. The luteal phase group had a mean HA content intermediate between the pre- and post-LH surge groups, and was significantly different from either. The frequency of cervical samples containing both sizes of HA fragments (small and large) was significantly higher (P<or=0.05) in the pre-LH surge group compared with the luteal and the post-LH surge groups, whereas that in post-LH surge group was significantly (P<or=0.05) higher than that in the luteal group. The number of cervical samples that contained only small HA fragments was significantly (P<or=0.05) higher in the luteal group compared with both the pre- and post-LH surge groups, whereas the number of samples containing only large HA fragments was significantly (P<or=0.05) higher in the post-LH surge group compared with the luteal or pre-LH surge groups. Overall mean expression of CD44 in the vaginal and mid regions was significantly (P<or =0.001) higher than that in the uterine region, with no difference between the vaginal and mid regions of the cervix. Pattern of CD44 expression depended on the stage of the oestrous cycle. At the luteal stage, CD44 expression did not vary among epithelial, sub-epithelial, circular and longitudinal smooth muscle layers, whereas at the pre- and post-LH surge stages, the expression in the epithelial layer was significantly (P<or=0.001) higher than that in the other three layers. In general, CD44 expression in the transverse smooth muscle layer was significantly (P<or=0.05) lower than the expression in all the other layers at all the stages of the oestrous cycle. The results indicated that the HA varied with the steroid status. Higher HA values at a time when cervical relaxation is naturally higher may indicate its involvement in remodelling of the cervix at oestrus.
绵羊的宫颈复杂解剖结构限制了经宫颈人工授精的成功率。然而，在发情期宫颈有一定程度的自然松弛，同时含水量增加。由于透明质酸（HA）与水分子有很强的亲和力，因此在这项研究中，我们假设宫颈中的 HA 含量、HA 不同大小片段的比例以及其受体 CD44 的表达随发情周期的阶段而变化。在 25 只威尔士山地羊中同步发情，并在发情周期的黄体期（n=8）、LH 前（n=8）或 LH 后（n=9）峰期采集它们的宫颈。LH 前峰期组 HA 含量最高（2.96ng/mg 宫颈组织），明显高于 LH 后峰期组（2.04ng/mg）（P<0.05）。黄体期组的 HA 含量处于 LH 前和 LH 后峰期组之间，与两组均有显著差异。含有两种大小（小和大）HA 片段的宫颈样本频率在 LH 前峰期组显著升高（P<0.05），与黄体期和 LH 后峰期组相比，而 LH 后峰期组明显高于黄体期组（P<0.05）。仅含有小 HA 片段的宫颈样本数量在黄体期组显著升高（P<0.05），与 LH 前和 LH 后峰期组相比，而仅含有大 HA 片段的样本数量在 LH 后峰期组显著升高（P<0.05），与黄体期或 LH 前峰期组相比。阴道和中部区域的 CD44 平均表达显著（P<0.001）高于子宫区域，宫颈阴道和中部区域之间无差异。CD44 表达模式取决于发情周期的阶段。在黄体期，上皮、上皮下、环形和纵向平滑肌层之间的 CD44 表达没有差异，而在 LH 前和 LH 后峰期，上皮层的表达明显高于其他三层（P<0.001）。一般来说，在发情周期的所有阶段，横形平滑肌层的 CD44 表达明显低于所有其他层（P<0.05）。结果表明，HA 随类固醇状态而变化。在宫颈自然松弛度较高时，HA 值较高可能表明其参与发情期宫颈重塑。
