title: Switching of the Laryngeal Cavity From the Respiratory Diverticulum to the Vestibular Recess: A Study Using Serial Sagittal Sections of Human Embryos and Fetuses.
abstract: A cecum-like protrusion of the pharynx (the laryngeal cecum or vestibular recess [VR]) develops immediately anterior to the laryngeal part of the respiratory diverticulum. An expansion of the VR has been well described, whereas the fate of the diverticulum is still obscure, although its pharyngeal opening corresponds to the glottis. We observed sagittal sections of 10 embryos (five specimens at 5-6 weeks and another five at 7-8 weeks) and eight fetuses at 25-30 weeks. At 5-6 weeks, a lumen of the laryngeal part of the respiratory diverticulum appeared, and subsequently, the VR opened into the epithelial lamina. Because of this discrete separation, it seemed unlikely that the pharyngeal pouches contributed to the laryngeal epithelium. At 6-7 weeks, the VR exhibited a high boot-shaped lumen with canalization to the diverticular lumen at the level of the cricoid cartilage. Thus, in a midline area between the bilateral arytenoid cartilages, double laryngeal lumina were evident, separated by the thick midline epithelial lamina. At 25-30 weeks, the inferior part of the VR lumen had become enlarged because of the destruction of the epithelial lamina along the arytenoid and corniculate cartilages. In contrast, candidates for the initial diverticular lumen remained as epithelial slits in the anterosuperior side of the transverse arytenoid muscle. Therefore, the final anterior and lateral laryngeal walls seemed to originate from the VR with canalization, in contrast to the part of the posterior wall derived from the initial diverticular wall.
authors.affiliation: Department of Anatomy, Tokyo Dental College, Tokyo, Japan. Electronic address: yamamotomasahito@tdc.ac.jp.
authors.forename: Masahito
authors.initials: M
authors.lastname: Yamamoto
authors.affiliation: Department of Otolaryngology and Head and Neck Surgery, Graduate School of Medicine, Tohoku University, Sendai, Japan.
authors.forename: Yohei
authors.initials: Y
authors.lastname: Honkura
authors.affiliation: Institute of Embryology, Complutense University Madrid, Madrid, Spain.
authors.forename: Jose Francisco
authors.initials: JF
authors.lastname: Rodríguez-Vázquez
authors.affiliation: Division of Internal Medicine, Iwamizawa Asuka Hospital, Iwamizawa, Japan.
authors.forename: Gen
authors.initials: G
authors.lastname: Murakami
authors.affiliation: Department of Otolaryngology and Head and Neck Surgery, Graduate School of Medicine, Tohoku University, Sendai, Japan.
authors.forename: Yukio
authors.initials: Y
authors.lastname: Katori
authors.affiliation: Department of Surgery, Faculty of Medicine, Chonbuk National University, Jeonju, Korea.
authors.forename: Baik Hwan
authors.initials: BH
authors.lastname: Cho
authors.affiliation: Department of Anatomy, Tokyo Dental College, Tokyo, Japan.
authors.forename: Shin-Ichi
authors.initials: S
authors.lastname: Abe
mesh_terms: D001193:Arytenoid Cartilage / Q000196:embryology; D002454:Cell Differentiation; D019070:Cell Lineage; D003413:Cricoid Cartilage / Q000196:embryology; D005865:Gestational Age; D005931:Glottis / Q000196:embryology; D006801:Humans; D007820:Laryngeal Mucosa / Q000196:embryology*; D007821:Laryngeal Muscles / Q000196:embryology; D007830:Larynx / Q000196:embryology*; D009024:Morphogenesis; D010614:Pharynx / Q000196:embryology
keywords: Human embryo; Laryngeal cecum; Laryngeal ventricle; Pharyngeal pouch; Respiratory diverticulum; Vestibular recess