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Authors:  Kei Kitamura^1†, Yuki Sugiyama^2† , Kotoko Imai², Tianyi Yang², Ryo Sekiya², Kazuma Morita², Gen Murakami^2&3 , Hitoshi Yamamoto¹, Shin-ichi Abe².  

1. Department of Histology and Developmental Biology, Tokyo Dental College, Tokyo, Japan Email : keikitamura@tdc.ac.jp hyamamoto@tdc.ac.jp ORCID: 0000-0003-3335-1440

2. Department of Anatomy, Tokyo Dental College, Tokyo, Japan. Email : sugiyamayuki@jikei.ac.jp timaik@tdc.ac.jp yoteni@tdc.ac.jp sekiyaryo@tdc.ac.jp kmorita@tdc.ac.jp abesh@tdc.ac.jp ORCID: 0000-0003-4632-9736

3. Division of Internal Medicine, Iwamizawa Aska Hospital, Iwamizawa, Japan. Email : g.murakamisaori@gmail.com ORCID 0000-0001-7181-5475

† These authors contributed equally to this work

Abstract:

The mucocutaneous junction (MCJ) is a specific site located at body orifices such as the mouth, nose, eyelid, vulva, prepuce, and anus. The present study was conducted to reassess the MCJ in terms of 1) cytokeratin expression, 2) the distribution of immunoreactive cells, 3) nerves and their terminals, and 4) differences between near-term fetuses and adults. For cadaveric specimens after long-term preservation, cytokeratin 14 was useful for identification of the MCJ. In near-term fetuses, routine histology clearly demonstrated the putative MCJ due to transient, thick stratification of the squamous epithelium. This was most evident in the oral mucosa and less evident in the palpebral skin. In the anus and eyelid, the MCJ developed from highly proliferative epithelia of the anal sinus and meibomian gland, independent of the growing skin and mucosa. In elderly individuals, the MCJ was expanded in the nose and anus possibly as a result of mechanical stimuli, and was apparently connected to a hemorrhoid venous plexus. At the vulva and prepuce, a morphology intermediate between pseudostratified columnar and stratified squamous epithelia was evident. Except for the vulva and prepuce, corpuscle like nerve terminals were sandwiched between the dermal papillae and epidermis, whereas nerves arranged in parallel exhibited free ends beneath the mucosa. At the anus, the myenteric autonomic nerve plexus disappeared slightly orad to the MCJ. Langerhans cells were richly distributed in the skin stratum spinosum, while suppressive T lymphocyte clusters were present in the lamina propria mucosae. General rules and site-specificity of the MCJ were reviewed.

Keywords:

Mucocutaneous junction, lower lip, eyelid, external nasal orifice, vulva, prepuce, anus, immunohistochemistry, human fetus, elderly cadaver.

Citation:

Kitamura K. The mucocutaneous junction and its associated nerves, immunoreactive cells and changes with age: a review with novel observations from human fetal and cadaveric specimens. Annals of Dermatological Science 2024.