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

Abstract

Objective:This study investigated the comparative morphological analysis of the vomeronasal organ and the accessory olfactory bulb in dogs and rabbits.Materials and Methods:A total of 15 heads obtained from each adult healthy Balady dog (Canis familiaris) and New Zealand rabbit (Oryctolagus cuniculus) of both sexes. The animals were sedated and anesthetized. Then, the heads were removed for computing topography, gross, and cross-sectional anatomy and histological techniques.Results:The vomeronasal organ was blind bilateral tubes enclosed by J-shaped cartilage on each side of the nasal septum. In dogs, it extended from the level of the upper third premolar teeth to the third incisive teeth. While in rabbits, it had no relation with the upper teeth. In cross section, the vomeronasal organ was pear-shaped in dogs and oval in rabbits. The accessory olfactory bulb was a small oval-shaped in dogs, but larger and ovoid in rabbits with clear lamination in its structure. The vomeronasal epithelium in rabbits was higher in its thickness than that of the dog. The vomeronasal duct had medial sensory and lateral respiratory epithelium. The vomeronasal glands were voluminous and of serous type in rabbits other than were seromucous in dogs.Conclusion:The most characteristic structural variations achieved in the vomeronasal organ and the accessory olfactory bulb of the dog and rabbit gave an indication that the organ was more functional in rabbits than in dogs. The detection and response to the pheromonal stimuli were referred to as the occurrence of olfactory epithelium in the vomeronasal organ.

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

“…A small median diamond‐shape prominence, the incisive papilla, was located just caudal to the secondary incisors. In accordance with that of Mahdy, El behery, and Mohamed (2019), who reported that the incisive papilla is flanked on both side by a groove on which the oral orifices of the nasopalatine ducts were opened. The nasopalatine ducts pass dorsocaudally through the palatine fissure to open into the floor of the nasal cavity providing a connection between the oral cavity and the nasal cavity (Mahdy et al, 2019; Villamayor, Cifuentes, Fdz.‐de‐Troconiz, & Sanchez‐Quinteiro, 2018).…”

“…In accordance with that of Mahdy, El behery, and Mohamed (2019), who reported that the incisive papilla is flanked on both side by a groove on which the oral orifices of the nasopalatine ducts were opened. The nasopalatine ducts pass dorsocaudally through the palatine fissure to open into the floor of the nasal cavity providing a connection between the oral cavity and the nasal cavity (Mahdy et al, 2019; Villamayor, Cifuentes, Fdz.‐de‐Troconiz, & Sanchez‐Quinteiro, 2018). The duct allows the passage of chemosignal form of pheromones together with aspirated air from the rabbit mouth into the nose through the vomeronasal organ (Villamayor et al, 2018).…”

Histological Features of the Vomeronasal Organ in New Born Lambs (Ovis aries)

“…The heights of the respiratory epithelia were 31.15±0.71 µm in male and 29.75±0.79 µm in female at the rostral portion, meanwhile those in middle portion were 31.09±0.86 µm in male and 31.09±0.80 µm in female. This result dissimilar to results of adult mammals recorded by (5) , (6) , (17) , (20) , (21) , (22) (23) , (25) , (29) and (30) . The current results suggested that the respiratory epithelium has displayed few population of goblet cells, this feature revealed that the function of new born lamb vomernasal organ could be limited because that the mucous secretion of the goblet cells is so important as a part of mechanical apparatus of pumping system, this observation is supported (10) and (26) .…”

“…The epithelia were similar those in adult mammals which mentioned by all authors with exception in newly born lamb the epithelia were revealing still differentiation (Late morphogenesis, transformation and growth). This result has recorded by (13) in Gazelle, (6) in Ox, (17) in buffalo, (18) , (19) in camel, (5), (9) in sheep, (20) , (21) in canine, (12) in equine, (22) in male red fox, (23) in Adult Guinea pig, (24) in giraffe, (25) in bear. On other hand this result disagrees with (26) in goat, (12) in horse who mentioned that the respiratory epithelium is only type in rostral portion of organ.…”

“…The hyaline cartilage was enclosing the vomernasal duct completely with except small silt like opening which seen at the dorsal aspect of the cartilage (fig. 1), similarly to all mammals, the vomeronasal organ of newly born lamb is enclose and supported by cartilage which at the pre rostral portion, meanwhile at vomernasal duct the cartilage has completely enclosed the vomernasal duct, this result paralleled with results of (5) in sheep, (26) in goat, (20) , (21) in doges, (25) in the brown bear, (27) in monkey, and in male red fox (22) . This result suggest that the incomplete condition of cartilage serve to gives the vomernasal duct a required distention during pumping mechanism (6) , (28) , so is give an idea that the vomernasal organ had functional statues also the variable shape of the lumen of vomernasal duct, on the other hand the incomplete cartilage lead to allow the blood supply into the soft tissue of the vomernasal organ from nasal mucosa, this agrees with results (5) , (8) and (6) The lateral walls respiratory epithelium was pseudo stratified columnar epithelium showed few of goblet cells and composed of (Ciliated columnar cells, non-ciliated goblet cells & basal cells) and revealed poor ciliogenesis (fig.…”