The morphology of the inner ear from the domestic pig (Sus scrofa)

Abstract

SummaryThe morphology of the hair cells of the inner ear end organs from the domestic pig (Sus scrofa) have been studied using a combination of Scanning and Transmission Electron Microscopy (SEM and TEM), revealing hair cells from the cochlea and vestibule using a novel surgical and technical approach. This is the first time that the inner ear hair cells from S. scrofa have been studied, thus providing useful anatomical information on the morphology of the hair cells from the cochlea, saccule and utricle from a large mammal. Anatomical information in relation to the morphology of the inner ear is of considerable importance, both in the pathological diagnosis of trauma and in the development of cochlea implants and other biotechnological systems associated with the enhancement of hearing. Standard fixation protocols using cardiac perfusion was not employed in this study as this method cannot always be applied, such as the pathological examination of the human ear, or the study of animals protected by endangered species legislation. With the exception of a very few countries, cetaceans cannot be killed for research purposes, yet physiological information on the inner ear from these species is urgently required for ecological assessment reasons. Supporting the use of S. scrofa as a model for cetacean hearing research is that this animal is a member of the order Artiodactyla, which includes both the hippopotamus and cetaceans. Being of a similar size, the pig is an ideal subject for developing protocols and surgical techniques required to investigate both the human and small cetacean auditory systems.

Scanning and Transmission Electron Microscope Examination of Cochlea Hair and Pillar Cells from the Ear of the Mongolian Gerbil (Meriones unguiculatus)

“…In humans, the cochlea is coiled approximately two and one-half turns around the modiolus, and in M. unguiculatus it is coiled two and three-quarter turns. The diversity in the number of spiral turns in the cochlea and variation in the basilar membrane length between rodents can be seen in Table 1 [46]. The number of cochlea turns and the basilar membrane length from M. unguiculatus, (identified in this study) have also been included, along with the hearing frequency range as defined by Ryan [34].…”

“…Encapsulating bone was carefully removed from the continuously submerged cochlea using the micro burr, fine forceps and a needle probe. On completion, the cochlea was dehydrated through a graded ethanol series ranging from 35% through 50%, 70% and 90% to absolute ethanol, prior to desiccation using the critical point drying method used by Lovell et al [46]. Fully desiccated end organs were subsequently mounted on a specimen stub using either a carbon tab or silver dag, and coated with c. 8 nm of gold in an Emitech K 550 sputter coater (working at approximately 2 x 10 -6 Torr).…”

“…The TEM preparation methodology employed in this study was based on techniques used by Lovell & Harper [46]. As with the SEM methodology, the heads of four mature male gerbils were divided medially and the periotic bone containing the inner ears from the left and right sides were removed and placed into chilled fixative for two hours.…”

Potential protective effect of N-acetyl cysteine in acoustic trauma: An experimental study using scanning electron microscopy

“…Then, the cochlea was dehydrated through a graded ethanol series, prior to desiccation, using a critical-point drying method described by Lovell et al 7 Fully desiccated samples were mounted on a specimen stub using a carbon tab. After critical-point drying using CO 2 and sputter-coating with gold according to standard procedures, specimens were investigated with a Zeiss Ultra 50 SEM operating at 5 kV accelerating voltage.…”

The Potential Protective Effects of 2-aminoethyl Diphenylborinate against Inner Ear Acoustic Trauma: Experimental Study Using Transmission and Scanning Electron Microscopy

“…The cochlea was applied to an ethanol series of 50%, 70%, 90%, and absolute ethanol for dehydration, and desiccation was then performed [13] . These samples were mounted on a specimen stub.…”