Micromorphological characteristics of the receptor part of the additional olfactory system of the common beaver
Authors:   Moscow State Academy of Veterinary Medicine and Biotechnology – MVA by K. I. Skryabin”, Moscow, Russia, Slesarenko Natalya A. , Gorelikov Peter L. ,   Moscow State Academy of Veterinary Medicine and Biotechnology – MVA by K. I. Skryabin”, Moscow, Russia, Oganov Eldiyar O. ,   Moscow State Academy of Veterinary Medicine and Biotechnology – MVA by K. I. Skryabin”, Moscow, Russia, Demidov Artem A. ,   Moscow State Academy of Veterinary Medicine and Biotechnology – MVA by K. I. Skryabin”, Moscow, Russia
Published: March 2023

The article presents the microscopic organization of the vomeronasal organ (VNO), membranes, vascular system and innervation of the VNO of the common beaver. A comparative analysis of the patterns and features of the structure of the organ in comparison with other representatives of the mammalian family is given. The research was carried out on the basis of the Department of Anatomy and Histology of Animals named after Professor A. F. Klimov of the Moscow State Academy of Veterinary Medicine and Biotechnology – MBA named after K. I. Scriabin. The objects of research were 10 common beavers aged 2 to 6 years, without pronounced signs of pathology of the nasal and oral cavities. The animals were selected from hunting farms of the Moscow region in connection with planned slaughter. When studying the macro- and micromorphological features of the vomeronasal organ, a comprehensive methodological approach was used, including classical and fine anatomical dissection under the control of a binocular magnifying glass with illumination, followed by a description of the studied structures, as well as histological examination with further light microscopy of sections of VNO stained with hematoxylin and eosin and toluidine blue by the Nissl method. It was found that the common beaver has a vomeronasal organ, which is a receptor part of the additional olfactory system, has general patterns of morphological organization characteristic of representatives of other taxonomic categories. At the same time, we have identified species-specific micromorphological features characteristic of representatives of the rodent family. So in the middle part of the ventral wall of the cavity of the external cavity there is a specific depression, the multilayer epithelium of which differs from the border epithelium on both sides. In addition, lacunar-type capillaries are located in the own plate of the sensory epithelium, a large muscle-type vein with a large number of somatic-type capillaries is located contralaterally. The endings of the vomeronasal nerve (VNN) in the walls of the ordinary beaver have their own topographic features. In the area of the mucous membrane of the sensory epithelium, the nerve branches are located transversely along the course of the VNO channel. The innervation of the mucous membrane of the respiratory epithelium has the opposite direction – the branches of the nerve are located along the course of the organ channel. In the submucosal base of the mucous membrane from the respiratory epithelium, ventrally from the wall of the muscle-type vein, there are single, small singly located neurons of the intramural ganglion.