Understanding the anatomy of ears from guinea pigs and rats and its use in basic otologic research

The use of animal samples is important in otologic research and understanding the anatomy of their ears help make proper use of them in research projects. Aim: to study guinea pig’s and rat’s ears under light microscopy(LM) and scanning electron microscopy(SEM) and understand their anatomical advantages in basic otologic research. Materials and methods: The temporal bones, tympanic bullas and cochleas from three albino guinea pigs and rats were photographed and analyzed under LM and SEM. Results: Rats aren’t as simple to handle as guinea pigs, and often present with otitis media. Rats have a fragile junction of the tympanic bulla, two and half turns in the cochlea, and their tympanic membranes do not seal off the entire external auditory canal. Guinea pigs have full bullas, their incus and malleus are fused and they have three and half cochlear turns. Under SEM, guinea pigs and rats have Tectori Membrane, Raissner’s Membrane and the Organ of Corti. Only guinea pigs have Hensen’s Cells. Conclusion: Guinea pigs were considered easy to handle for microdissection purposes because of the size and robustness of their temporal bones, and for surgical experiments involving the stapes, the oval window and the tympanic membrane. Under SEM there are similarities guinea pigs and rats, and both can be used in inner ear studies.