Morphogenesis of Olfactory organ of the eastern long-necked turtle (Chelodina longicollis)
Keywords:turtles, olfactory organ, main olfactory epithelium, vomeronasal epithelium
The study of olfactory analyzer development of reptiles is very important in evolutionary and comparative-anatomical aspects. The olfactory analyzer of different reptiles has significant differences in morphology. The olfactory analyzer of lizards and snakes is anatomically divided into the main and accessory (vomeronasal) systems. The olfactory organ of turtles has distinctive features of organization. There is no morphological separation between the main olfactory and vomeronasal systems in the olfactory organ of most turtles.
The article describes the key stages of olfactory structures development of eastern long-necked turtle (Chelodinalongicollis). The olfactory organ consists of vestibulum, nasal cavity and nasopharyngeal duct, which opens into the oral cavity through choanae. The nasal cavity is divided by a narrow section of non-sensory epithelium into a dorsal part, which is lined by olfactory epithelium, and ventral, which is lined by vomeronasal epithelium. The ventral part of the nasal cavity has medial diverticula, which significantly increases the volume of the vomeronasal epithelium. The olfactory epithelium has numerous Bowman's glands, that are absent in the vomeronasal epithelium. The duct of the lateral olfactory gland opens at the place of transition of the vestibulum into the nasal cavity. This gland moisturizes the main olfactory epithelium, which is most in contact with air. The presence of the vomeronasal nerve, individual fibers of which depart from the ventral part of the nasal cavity and enter the medial surface of the olfactory bulb, confirms the existence of the vomeronasal system in turtles.
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