Conhecimento da anatomia da orelha de cobaias e ratos e sua aplicação na pesquisa otológica básica

Abstract

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.

Macroscopic description of the external and middle ear of paca (Cuniculus paca Linnaeus, 1766)

“…The location of the temporal bone and tympanic bulla in the paca resembles the descriptions of this organ in domestic animals (Nickel et al 1979, Nomina Anatomica Veterinaria 2005, Dyce et al 2010, König & Liebich 2011, guinea pigs (Cooper & Schiller 1975, Oliveira 1982, Wysocki 2005, Albuquerque et al 2009), rats (Wysocki 2008, Albuquerque et al 2009), and humans ( Didio 1999, Grabowski & Tortora 2002.…”

“…The squamous bone with an ivory-like aspect, with rugosities and regions of bone aeration observed in the paca is not detected in guinea pigs (Wysocki 2005, Albuquerque et al 2009), rats (Wysocki 2008) or domestic animals. Also, in contrast to guinea pigs (Wysocki 2005, Albuquerque et al 2009), rats (Wysocki 2008) and domestic animals (Ni- ckel et al.…”

“…Also, some facility of handling and of manipulation and dissection of the guinea pig's cochlea has been observed. The bone fragility of the tympanic bulla of the rat favors its opening for the exposure of structures of the middle ear and cochlea, but also involves easy destruction when the temporal bone is removed (Albuquerque et al 2009). …”

Effect of moderate intensity noise exposure on the cochlea of adult male guinea pig and the possible protective role of Pravastatin: Histological study

“…Moreover, guinea pigs' hearing and vestibular systems are very similar to those of humans and that with SEM the guinea pig cochlea has three and half turns and that of the rat has two and half [14,15] . Previous investigators noticed the presence of Hansen Cells only in the guinea pigs' turns therefore, guinea pigs were the animals of choice for our study [14,15] .…”

Micro-endoscopic ear anatomy of guinea pig applied to experimental surgery

“…There are many descriptions of guinea pigs ear anatomy, but few studies concern about its surgical and endoscopic correlations 2,3 .…”