Williams L M, Hollingsworth M, Dixon J S
J Reprod Fertil. 1982 Sep;66(1):203-11. doi: 10.1530/jrf.0.0660203.
The isolated cervix from non-pregnant, early Day 22 pregnant (late pregnant) and parturient rats was studied. Cyclic loading and unloading tensile tests showed that the creep properties of the cervix were greater in late pregnant than in non-pregnant rats. This change in tensile properties, or softening, was associated with a marked rise in % of water and a fall of collagen concentration (as % of wet but not dry weight). These findings, plus electron micrographs showing a marked increase in extracellular matrix, separation of bundles of collagen fibrils and active fibroblasts, suggest that softening if related to controlled tissue hydration. Cervices were also removed from 3 groups of rats killed at different times during the 3-h parturient period and creep rate measured by continuous loading. A nearly 3-fold increase in creep rate over this period indicates that there is a second stage of cervical softening in pregnancy which precedes dilatation at parturition.
对未怀孕、妊娠第22天早期（妊娠晚期）和分娩期大鼠的离体子宫颈进行了研究。循环加载和卸载拉伸试验表明，妊娠晚期子宫颈的蠕变特性比未怀孕大鼠更强。拉伸特性的这种变化，即软化，与水分百分比的显著上升和胶原蛋白浓度的下降（以湿重而非干重的百分比表示）有关。这些发现，加上电子显微镜照片显示细胞外基质显著增加、胶原纤维束分离和活跃的成纤维细胞，表明软化与可控的组织水合作用有关。还从在分娩期3小时内不同时间处死的3组大鼠中取出子宫颈，并通过连续加载测量蠕变率。在此期间蠕变率增加了近3倍，这表明妊娠期间子宫颈软化存在第二个阶段，该阶段先于分娩时的扩张。
