From Cell Biology to Tissue Engineering


Cotton rats (Sigmodon hispidus) possess pharyngeal pouch remnants originating from different primordia

Teppei Nakamura1,2, Osamu Ichii2, Takao Irie3, Tatsuya Mizoguchi2, Akio Shinohara4, Hirokazu Kouguchi3, Yuji Sunden5, Saori Otsuka-Kanazawa2, Yaser Hosny Ali Elewa2,6, Chihiro Koshimoto4, Ken-ichi Nagasaki1 and Yasuhiro Kon2

1Section of Biological Safety Research, Chitose Laboratory, Japan Food Research Laboratories, Chitose, 2Laboratory of Anatomy, Department of Basic Veterinary Sciences, Faculty of Veterinary Medicine, Hokkaido University, 3Medical Zoology Group, Department of Infectious Diseases, Hokkaido Institute of Public Health, Sapporo, Hokkaido, 4Division of Bio-Resources, Department of Biotechnology, Frontier Science Research Center, University of Miyazaki, Kiyotake, Miyazaki, 5Laboratory of Veterinary Pathology, Faculty of Agriculture, Tottori University, Tottori, Japan and 6Department of Histology and Cytology, Faculty of Veterinary Medicine, Zagazig University, Zagazig, Egypt

Offprint requests to: Yasuhiro Kon, D.V.M., Ph.D, Laboratory of Anatomy, Department of Basic Veterinary Sciences, Faculty of Veterinary Medicine, Hokkaido University, Kita 18-Nishi 9, Kita-ku, 060-0818 Sapporo, Japan. e-mail: y-kon@vetmed.hokudai.ac.jp

Summary. Pharyngeal pouches in mammals develop into specific derivatives. If the differentiation of the pharyngeal pouches is anomalous, their remnants can result in cysts, sinuses, and fistulae in the differentiated organs or around the neck. In the present study, we found several pharyngeal pouch remnants, such as cystic structures in thymus and parathyroid gland and fossulae extended from the piriform fossa, in the inbred cotton rats maintained at Hokkaido Institute of Public Health (HIS/Hiph) and University of Miyazaki (HIS/Mz). In HIS/Hiph, the fossulae extended from the apex of the piriform fossa into the thyroid glands and were lined with stratified squamous and cuboidal epithelium. Calcitonin-positive C-cells were present within their epithelium in HIS/Hiph. In contrast, the fossulae of HIS/Mz ran outside the thyroid glands toward the parathyroid glands; they were lined with columnar ciliated epithelium and a few goblet cells, but had no C-cells, which was consistent with the cystic structures in the thymus and the parathyroid gland. These results indicated that the fossulae were a remnant of the ultimobranchial body in HIS/Hiph and of the thymopharyngeal duct in HIS/Mz. Thus, the fossulae of the piriform fossa resembled the piriform sinus fistula in human. In conclusion, cotton rats frequently possessed pharyngeal pouch remnants, including the piriform sinus fistula, and therefore, might serve as a novel model to elucidate the mechanisms of pharyngeal pouch development. Histol Histopathol 33, 555-565 (2018)

Key words: Cotton rat, Pharyngeal pouch remnant, Thymopharyngeal duct, Ultimobranchial body, Piriform sinus fistula

DOI: 10.14670/HH-11-946