Comparative Anatomy of the Vomeronasal Organ (VNO) in Sheep (Ovis aries) and Dogs (Canis familiaris) with Simple Reference to its Histological Structure and Vasculature Supply

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Gamal M. Allouch & Fahad A. Alshanbari


The vomeronasal organ (VNO) is located in the anteroinferior part of the nose and the accessory olfactory organ in mammals which is responsible of sense of smell. This study aims to compare the macro and microanatomical structure of the VNO between sheep and dogs. In the current study, we used ten adult slaughtered sheep and ten adult synchronized dogs with different sexes ages 1-2 years. The head of both animals were preserved in 10 % formalin for one week. This study shows in both animals, the VNO occupies the same position in the cavity of the vomer bone and the same relationship in the cranial part of the nasal cavity. Furthermore, the VNO is divided into three parts based on shape that are the rostral, central, and caudal part. The results show the VNO in sheep has a (U) shape and is opened dorsolaterally. It has a small and narrow cavity. It is long 6 cm long, and it has different diameters on its course. In comparison, the vomeronasal organ in dogs is very developed and has a (J) shape. It has a large and long cavity and ends at the fourth molar. Its length is about 10 cm, and it has one diameter on its course. The VNO receives the blood supply from the sphenopalatine and caudal palatine arteries. The present study shows main differences between sheep and dogs VNO in which the structure of vomeronasal bone between the sheep and dog is completely different. The finding will illustrate fundamental differences and provide specific structural differences between the two species.

KEY WORDS: Vomer-nasal; Morphological study; Sheep; Dog.

How to cite this article

ALLOUCH, G. M. & ALSHANBARI, F. A. Comparative anatomy of the vomeronasal organ (VNO) in sheep (Ovis aries) and dogs (Canis familiaris) with simple reference to its histological structure and vasculature supply. Int. J. Morphol., 42(2):374-381, 2024.