Adaptations of the rat vagina in pregnancy to accommodate delivery
Adaptations of the rat vagina in pregnancy to accommodate delivery
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DOI：
10.1097/01.aog.0000246798.78839.62
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发表时间：
2007-01-01
影响因子：
7.2
通讯作者：
Moalli, Pamela A.
中科院分区：
文献类型：
--
作者：
Daucher, James A.;Clark, Katherine A.;Moalli, Pamela A.
目的：表征妊娠、分娩和产后大鼠阴道的超微结构变化，重点关注胶原结构和平滑肌细胞形态。方法：采用透射电镜检查 4 只处女、4 只孕中期、4 只孕晚期、4 只立即和 4 只晚期阴道分娩大鼠的阴道。根据胶原纤维面积分数将图像分为四类之一，第 1 组每单位面积的胶原纤维数量最多，第 4 组每单位面积的胶原纤维数量最少。根据与肌原纤维相比，细胞器所占细胞质的体积分数，平滑肌细胞被分为三种细胞类型（“合成”、“中间”和“收缩”）。 结果：定量分析表明，处女大鼠中 76% 的胶原纤维被归类为第 1 组或第 2 组，而在怀孕中期、怀孕后期和刚产后动物中，这一比例为 49%、40% 和 23%。 （P=0.006）。产后晚期组织似乎与处女组织相似（77%）。与处女 (20%) 和产后晚期动物 (21%) 相比，妊娠中期 (37%)、妊娠晚期 (34%) 和产后即刻动物 (43%) 含有更高比例的合成平滑肌细胞 (P=.02)。与怀孕中期（42%）、怀孕晚期（50%）和产后即刻（50%，P=.05）相比，收缩性平滑肌细胞在处女（64%）和产后晚期（70%）动物中占主导地位。结论：在怀孕期间，胶原纤维面积减少，而平滑肌细胞从收缩表型转变为合成表型。产后后期胶原蛋白和平滑肌细胞形态均恢复至孕前水平。这些变化很可能代表了在胎儿通过期间尽量减少对阴道的创伤的适应。
OBJECTIVE: To characterize ultrastructural changes in the rat vagina in pregnancy, delivery, and postpartum, focusing on collagen architecture and smooth muscle cell morphology.METHODS: The vagina of four virgin, four midpregnant, four late pregnant, four immediate, and four late post-vaginal-delivery rats were examined by transmission electron microscopy. Images were classified into one of four categories based on collagen fibril area fraction, with group 1 containing the highest number of collagen fibers per unit area and group 4 containing the lowest. Smooth muscle cells were characterized into three cell types ("synthetic," "intermediate," and "contractile") based on the volume fraction of cytoplasm occupied by organelles compared with myofibrils.RESULTS: Quantitative analysis demonstrated that 76% of collagen fibers in virgin rats were categorized as group 1 or 2 compared with 49% in midpregnant, 40% in late pregnant, and 23% in immediate postpartum animals (P=0.006). Late postpartum tissue seemed similar to virgin tissue (77%). Midpregnant (37%), late-pregnant (34%) and immediate postpartum animals (43%) contained a higher proportion of synthetic smooth muscle cells compared with virgins (20%) and late postpartum animals (21%) (P=.02). Contractile smooth muscle cells predominated in virgin (64%) and late postpartum animals (70%) compared with midpregnant (42%), late pregnant (50%) and immediate postpartum (50%, P=.05).CONCLUSION: In pregnancy, collagen fiber area decreased while smooth muscle cells transformed from a contractile to a synthetic phenotype. The late postpartum period returned to prepregnant levels for both collagen and smooth muscle cell morphologies. It is likely that these changes represent adaptations to minimize trauma to the vagina during passage of the fetus.