妊娠和阴道分娩对肛提肌形态学及阴道黏膜神经分布的影响

Effect of pregnancy and spontaneous delivery on the morphology of levator ani muscle and expression of vaginal nerve fibers

目的探讨妊娠和阴道分娩对肛提肌形态学及阴道黏膜神经分布的影响。方法选取2006年6月至12月在北京协和医院妇产科阴道分娩的正常初产妇64例为阴道分娩组，选择同期行阴式手术的非妊娠期未产妇8例为对照组，取两组患者阴道前、后壁黏膜组织和肛提肌组织。对肛提肌组织进行组织学染色，观察肌肉形态学变化、测量肌纤维直径并进行分型。分别对阴道黏膜组织中蛋白基因产物9．5（PGP9．5）、血管活性肠肽（VIP）和神经肽Y（NPY）3种神经纤维进行免疫组化染色，分别计数阴道黏膜上皮层和固有层内每高倍视野（HPF）下3种抗体阳性神经纤维末梢的数量。结果阴道分娩组产妇肛提肌中I型肌纤维占79％。I型肌纤维平均直径（86±9）Ixm，II型肌纤维平均直径（79±15）Ixm。两组阴道黏膜标本中神经纤维数量比较，阴道分娩组阴道前壁黏膜上皮层内PGP9．5、VIP和NPY染色阳性的神经纤维数量分别为（5．9±3．3）、（7．6±3．1）和（8．2±3．2）条／HPF，均高于同组阴道后壁黏膜上皮层[分别为（3．8±2．9）、（5．9±3．1）和（6．0±3．0）条／HPF]，差异均有统计学意义（P〈0．05）；阴道分娩组阴道前壁黏膜固有层内PGP9．5和VIP染色阳性的神经纤维的数量[分别为（6．9±3．2）和（4．9±2．1）条／HPF]均高于正常对照组阴道前壁黏膜固有层[分别为（3．9±3．6）和（3．1±1．2）条／HPF]，差异也均有统计学意义（P〈0．05）。结论妊娠和阴道分娩会对肛提肌和盆底神经造成病理损伤。肛提肌适应妊娠期生理变化，肌纤维肥大。阴道前壁固有层内PGP9．5和VIP能神经纤维较丰富，有利于阴道壁内血管和平滑肌的扩张，为分娩做准备。

Objective To investigate the effect of pregnancy and spontaneous delivery on the morphologic characteristics of the levator ani muscle and innervation of the vaginal mucosa. Methods Eight nullipara without pelvic floor dysfunction （PFD） and 64 normal primipara undergoing spontaneous delivery were enrolled in this study during July to December 2006 in Peking Union Medical College Hospital. Biopsy specimens of levator ani muscle （ LAM ） and anterior and posterior vaginal walls were obtained from the puerpera as well as from the 8 nullipara undergoing vaginal operation. The structures of LAM were examined with histological techniques. Vaginal mucosa specimens were examined using immunohistochemistry staining for protein gene product 9.5 （ PGP 9.5 ）, vasoactive intestinal peptide （VIP） and ne uropeptide Y （ NPY）, and the positive stained nerve fibers were calculated respectively. Results The LAMs of the puerpera undergoing spontaneous delivery presented myogenetic and neurogenetic changes, both acute and chronic. Type Ⅰ muscular fibers were predominant（79% ）with both types increasing in diameters （（86 ± 9）um and （79 ±15 ） um]. Significantly different （ P 〈 0. 05 ） innervation of PGP 9. 5, VIP, and NPY nerve fiberswas observed between epithelial lamina of anterior vaginal wall（5.9 ± 3.3,7.6± 3. 1 and 8.2 ± 3.2, respectively） and that of posterior vaginal wall （3.8 ±2. 9, 5.9 ± 3. 1 and 6. 0 ±3.0, respectively）, with the nerve fibers being more in epithelial lamina of anterior vaginal wall, while no difference in the innervation of nerve fibers was observed in the lamina propria. Significantly different （ P 〈 0. 05 ） innervation of PGP 9. 5 and VIP nerve fibers was observed in the lamina propria of the anterior vaginal wall in puerperal undergoing vaginal delivery （6.9±3.2 and 4.9 ±2. 1） compared with those in nullipara （3.9 ±3.6 and 3. 1 ±1.2）. Conclusions Pathologic changes occur in LAMs and pelvic floor nerves during labor and delivery. LAM fibers become hypertrophy to adapt to the physiological changes during pregnancy. Richer innervation of PGP 9.5 and VIP nerve fibers in the lamina propria of the anterior vaginal wall in puerpera undergoing spontaneous delivery is beneficial for dilation of the blood vessels and smooth muscles and makes preparation for delivery.