Anat Cell Biol
Published online September 8, 2022
Copyright © Korean Association of ANATOMISTS.
1Department of Anatomy, Jeonbuk National University Medical School, Jeonju, Korea, 2Department of Anatomy, Wuxi School of Medicine, Jiangnan University, Wuxi, Jiangsu, China, 3Emeritus professor of Akita University, Akita, 4Division of Internal Medicine, Cupid Clinic, Iwamizawa, Japan, 5Department of Anatomy and Embryology, School of Medicine, Universidad Complutense de Madrid, Madrid, Spain, 6Department of Urology, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima, Japan
Correspondence to:Ji Hyun Kim
Department of Anatomy, Jeonbuk National University Medical School, 20 Geonji-ro, Deokjin-gu, Jeonju 54907, Korea
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
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.
Keywords: Imperforate hymen, Genital tubercle, Cloacal membrane, Corpus cavernosum of the clitoris, Anomaly