Comparative morpho-histological analysis on the vomeronasal organ and the accessory olfactory bulb in Balady dogs (Canis familiaris) and New Zealand rabbits (Oryctolagus cuniculus)

The vomeronasal system of the wolf (Canis lupus signatus): The singularities of a wild canid

Wolves, akin to their fellow canids, extensively employ chemical signals for various aspects of communication, including territory maintenance, reproductive synchronisation and social hierarchy signalling. Pheromone-mediated chemical communication operates unconsciously among individuals, serving as an innate sensory modality that regulates both their physiology and behaviour. Despite its crucial role in the life of the wolf, there is a lacuna in comprehensive research on the neuroanatomical and physiological underpinnings of chemical communication within this species. This study investigates the vomeronasal system (VNS) of the Iberian wolf, simultaneously probing potential alterations brought about by dog domestication. Our findings demonstrate the presence of a fully functional VNS, vital for pheromone-mediated communication, in the Iberian wolf. While macroscopic similarities between the VNS of the wolf and the domestic dog are discernible, notable microscopic differences emerge. These distinctions include the presence of neuronal clusters associated with the sensory epithelium of the vomeronasal organ (VNO) and a heightened degree of differentiation of the accessory olfactory bulb (AOB). Immunohistochemical analyses reveal the expression of the two primary families of vomeronasal receptors (V1R and V2R) within the VNO. However, only the V1R family is expressed in the AOB. These findings not only yield profound insights into the VNS of the wolf but also hint at how domestication might have altered neural configurations that underpin species-specific behaviours. This understanding holds implications for the development of innovative strategies, such as the application of semiochemicals for wolf population management, aligning with contemporary conservation goals.

Anatomical, histological, and surface ultrastructural evaluation of the palatal mucosa of domestic rabbit (Oryctolagus cuniculus)

The present study investigated the morphology of the palate of rabbit (Oryctolagus cuniculus). Samples from 12 healthy adult rabbits were examined by gross observation, morphometry, scanning electron and light microscopy. The hard palate was elongated and narrowed rostrally. The incisive papilla appeared as a diamond-shaped prominence flanked on both sides by a groove on which a slit-like opening of the nasopalatine duct opened. The palatine raphe was in the form of a groove. On either side of the raphe, 14-16 palatine ridges were present. The direction of these ridges differed according to their position. An incomplete (short) palatine ridge was occasionally present at the caudal part of the hard palate. Several gland openings were scattered on the surface of the palatine ridges. The soft palate extended to about the middle of epiglottis caudally. Its ventral surface had numerous thin transverse mucosal folds separated by furrows, and several openings of glands. Histologically, the incisive papilla, palatine ridges, and soft palate were lined by a parakeratinized stratified squamous epithelium resting on a dense connective layer of lamina propria. The degree of keratinization and the thickness of the lamina propria decreased caudally. Seromucoid glands were present in the rostral and caudal parts of the hard palate, as well as in the soft palate. In conclusion, the palate of rabbit presented characteristic features suggesting functional adaptations for their herbivores diet. Studying the morphological characteristics of the hard and soft palate of rabbits will help veterinary practitioners to investigate pathology malformations and diseases of the oral cavity.