Morphological and Morphometrical Study of Middle Ear Ossicles in 91 to 117-Day-Old Makouei Sheep Fetuses

Document Type : Basic Sciences


Department of Basic Sciences, Faculty of Veterinary Medicine, University of Urmia, Urmia, Iran


BACKGROUND: The middle ear ossicles have a fundamental role in the transmission of sound to the inner ear and therefore it will lead to sound understanding. There is no anatomical and morphometrical research performed on this organ in 91 to 117-day-old Makouei sheep fetuses. OBJECTIVES: Morphological and morphometrical study of middle ear ossicles in Makouei sheep fetuses. METHODS: For this study 8 sheep fetuses at the age of 91 to 117 days were collected from Urmia slaughter-house, then the heads were cut and the middle ear ossicles were obtained from the tympanic bulla and each of the ossicles were assessed anatomically by means of stereomicroscope.Then factors such as shape, dimensions and processes of each of the ossicles were measured. RESULTS: Anatomical results showed that the tympanic cavity contains three middle ear ossicles; respectively Malleus, Incus and Stapes. Rostral process of malleus wasn’t found but in the same place, there was a osseous lamina between the head and muscular process of the malleus that continues to the tympanic ring. Lenticular bone and muscular process of incus weren’t found. There was a distinctive surface at the junction of the head and caudal crus of stapes for the stapedius muscle insertion. CONCLUSIONS: In this study, anatomical findinges of ossicles are similar to the other animals but there are some differences in these fetuses that can be useful for study of evolution and creation process and diagnosis of anomalies. For statistical analysis, one-way ANOVA and Tukey’s post-hoc test were used, and the value of P<0.05 was considered as the criterion for statistical significance.


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