Kim Ji Hyun, Jin Zhe-Wu, Abe Hiroshi, Murakami Gen, Rodríguez-Vázquez José Francisco, Hinata Nobuyuki
Department of Anatomy, Jeonbuk National University Medical School, Jeonju, Korea.
Department of Anatomy, Wuxi School of Medicine, Jiangnan University, Wuxi, Jiangsu, China.
Anat Cell Biol. 2022 Dec 31;55(4):475-482. doi: 10.5115/acb.22.082. Epub 2022 Sep 8.
Solitary distal vaginal atresia is generally caused by a transverse septum or an imperforate hymen. We found a novel type of distal vaginal atresia in a late-term fetus (gestational age approximately 28 weeks) in our histology collection. This fetus had a vaginal vestibule that was closed and covered by a thick subcutaneous tissue beneath the perineal skin in the immediately inferior or superficial side of the imperforate hymen. The uterus, uterine tube, anus, and anal canal had normal development. The urethral rhabdosphincters were well-developed and had a normal topographical relationship with the vagina, but the urethrovaginal sphincter was absent. Thus, vaginal descent seemed to occur normally and form the vestibule. However, the external orifice of the urethra consisted of a highly folded duct with hypertrophied squamous epithelium. Notably, the corpus cavernosum and crus of the clitoris had poor development and were embedded in the subcutaneous tissue, distant from the vestibule. Normally, the cloacal membrane shifts from the bottom of the urogenital sinus to the inferior aspect of the thick and elongated genital tubercle after establishment of the urorectal septum. Therefore, we speculate there was a failure in the transposition of the cloacal membrane caused by decreased elongation of the genital tubercle. The histology of this anomaly strongly suggested that the hymen does not represent a part of the cloacal membrane, but is instead a product that appears during the late recanalization of the distal vagina after vaginal descent. The transverse septum was also likely to form during this recanalization.
孤立性阴道远端闭锁通常由横隔或处女膜闭锁引起。我们在组织学收集的一个晚期胎儿（孕周约28周）中发现了一种新型的阴道远端闭锁。该胎儿的阴道前庭封闭，在处女膜闭锁紧邻下方或浅表侧的会阴皮肤下被厚厚的皮下组织覆盖。子宫、输卵管、肛门和肛管发育正常。尿道横纹括约肌发育良好，与阴道有正常的位置关系，但尿道阴道括约肌缺失。因此，阴道下降似乎正常发生并形成前庭。然而，尿道外口由高度折叠的管道组成，鳞状上皮肥大。值得注意的是，阴蒂海绵体和脚发育不良，埋于皮下组织中，远离前庭。正常情况下，尿直肠隔形成后，泄殖腔膜从尿生殖窦底部移至增厚且延长的生殖结节下方。因此，我们推测由于生殖结节伸长减少导致泄殖腔膜移位失败。这种异常的组织学强烈提示处女膜并非泄殖腔膜的一部分，而是阴道下降后远端阴道再通后期出现的产物。横隔也可能在此再通过程中形成。
