Document Type : Original Article
Department of Anatomy and Embryology, Faculty of Veterinary Medicine, Benha University, Benha, Egypt
Department of Anatomy and Embryology, Faculty of Veterinary Medicine, Benha University
Since the inner ear is the main part of the auditory apparatus that is responsible for hearing and balance function, and it is also the first part of the ear to be developed, the current study aimed to investigate its development in the rabbit, as this type of research in this species is very scarce. About 20 fetuses aged 12 to 25 embryonic days(E) and 30 neonatal rabbits from birth to 20 days after birth (DAB) were used in this study. Samples were collected and fixed in 10-15% neutral buffered formalin for 48-72 hours and routinely prepared for histological and immunohistochemical investigation. The findings revealed that at E12, the otic placode, which is the embryonic origin of the inner ear, was formed. The placode was invaginated, forming the otic vesicle at E14, which grew and reshaped gradually as the development progressed, as appeared at E17, E20, and E25. Postnatally, the organ of corti, the main structure, continued to develop until reaching its mature form on day 15. The immunohistochemical investigations showed that S100 was a more specific marker for labeling the neurons of the spiral ganglia and the nerve fibers of both cochlear and vestibular nerves than calretinin. In conclusion, the present study revealed that the inner ear development started with the otic vesicle formation on the 14th day of gestation, then grew gradually as the development progressed, and continued till the organ of the corti reached its maturity on the 15th day postnatally, where the rabbit can normally hear.