title: Fetal Development of the Incisive Canal, Especially of the Delayed Closure Due to the Nasopalatine Duct: A Study Using Serial Sections of Human Fetuses.
abstract: The incisive canal of the incisive bone or premaxilla is a narrow bony canal through which pass the nasopalatine nerve and its concomitant vessels. However, its fetal development remains obscure. To assess its development, serial frontal sections of the heads of 26 human fetuses, of gestational age 9-20 weeks (crown-rump length, 46-183 mm), were examined. The nerve initially passed through a wide loose tissue space, but after ossification of the upper part of the incisive bone at 12-15 weeks, the canal became narrow and filled with tight fibrous tissue. Canals in seven fetuses were dilated and open unilaterally or bilaterally. In two of these seven fetuses, a nasopalatine duct passed through the canal and connected the nasal cavity to a central lumen of the paramedian epithelial pearl in the incisive fossa (not to an oral cavity). Even if the canal was closed, the duct was likely to remain above and below the closed part. Paramedian pearls were present in all specimens larger than 110 mm (15 weeks), with or without association of midline pearls. These paramedian pearls usually protruded toward and/or extended into the dilated or open canal, suggesting that these pearls, not any primitive oronasal communication pathway, contributed to keeping the canal open. The dilated canal, located on the superomedial side of the second and third teeth buds, seemed to be usually closed by further ossification. Even in fetuses, the nasopalatine duct seemed to be a variant or unusual phase of development temporally occurring after normal palate fusion. Anat Rec, 300:1093-1103, 2017. © 2016 Wiley Periodicals, Inc.
authors.affiliation: Department of Anatomy, Seonam University College of Medicine, Namwon, Korea.
authors.forename: Ji Hyun
authors.initials: JH
authors.lastname: Kim
authors.affiliation: Department of Oral Growth and Development, Fukuoka Dental College, Fukuoka, Japan.
authors.forename: Kyoko
authors.initials: K
authors.lastname: Oka
authors.affiliation: Department of Anatomy, Histology and Embryology, Yanbian University Medical College, Yanji City, Jilin Province, China.
authors.forename: Zhe Wu
authors.initials: ZW
authors.lastname: Jin
authors.affiliation: Division of Internal Medicine, Iwamizawa Asuka Hospital, Iwamizawa, Japan.
authors.forename: Gen
authors.initials: G
authors.lastname: Murakami
authors.affiliation: Department of Anatomy and Human Embryology, Faculty of Medicine, Institute of Embryology, Complutense University, Madrid, Spain.
authors.forename: José Francisco
authors.initials: JF
authors.lastname: Rodríguez-Vázquez
authors.affiliation: Department of Surgery, Chonbuk National University Hospital, Jeonju, Korea.|Research Institute of Clinical Medicine, Chonbuk National University-Biomedical Research Institute, Chonbuk National University Hospital, Jeonju, Korea.
authors.forename: Sung Woo
authors.initials: SW
authors.lastname: Ahn
authors.affiliation: Department of Surgery, Chonbuk National University Hospital, Jeonju, Korea.|Research Institute of Clinical Medicine, Chonbuk National University-Biomedical Research Institute, Chonbuk National University Hospital, Jeonju, Korea.
authors.forename: Hong Pil
authors.initials: HP
authors.lastname: Hwang
mesh_terms: D005147:Facial Bones / Q000196:embryology*; D005333:Fetus / Q000033:anatomy & histology; D005865:Gestational Age; D006801:Humans
keywords: delayed closure; epithelial pearl; human fetus; incisive canal; nasopalatine duct; os incisivum; premaxilla