The morphological and functional development of the stria vascularis in miniature pigs

Abstract

The purpose of this study was to examine the morphological and functional development of the lateral wall of the scala media of the cochlea in miniature pigs; light and transmission electron microscopy and electrophysiology were used for this purpose. We showed that the lateral wall of the scala media of the cochlea appears at embryonic Day 21 (E21) when the cochlear duct begins to form. From E28 to E49, the lateral wall can be distinguished according to its position along the cochlea. At E56, cells in the lateral wall begin to differentiate into three different types. At E70, three cell types, marginal, intermediate and basal, can be clearly distinguished. At E91, the stria vascularis is adult-like and the organ of Corti is also morphologically mature. The average endocochlear potential measured from the second turn of the cochlea (at E98, postnatal Day 1 (P1), P13 and P30) was 71.4±2.5 (n=7), 78.8±1.5 (n=10), 77.3±2.3 (n=10) and 78.0±2.1 mV (n=10), respectively. Our results suggest that in miniature pigs the stria vascularis develops during the embryonic period, concurrent with maturation of the organ of Corti. The magnitude of the endocochlear potential reached its mature level when the stria vascularis was morphologically adult-like at E98. These findings provide a morphological and functional basis for future animal studies using the miniature pig model concerning the pathogenesis of various inner-ear diseases.

Advantages of a miniature pig model in research on human hereditary hearing loss

“…Our previous studies have found that the size and morphology of pig cochlea are very similar to that of humans. Also similar with humans, the inner ear is essentially fully developed in pigs at birth with normal hearing ability ( Guo et al., 2015a , Guo et al., 2015b ). Compared with rodents which have delayed maturation of their auditory system and require continued inner ear development after birth before gaining normal hearing, the pig, as a large animal model, demonstrates promising prospect of applications in the field of otological research.…”

“…EUN chemical mutagenesis and spontaneous mutation animal models are useful in finding novel deafness pathogenic genes in animals and equivalent genes in humans. Genetic deafness animal models relate to protein encoding genes, tRNA or rRNA genes and microRNA, etc ( Guo et al., 2015a , Guo et al., 2015b ), encoding transcription factors, ion channels, transporter proteins, extracellular matrix, gap junction proteins, adhesion proteins, myosin, cytoskeletal proteins and microRNAs that regulate target gene expression.…”

Vestibular-evoked myogenic potentials in miniature pigs

“…Advantages of using miniature pigs include their relatively light bodyweight, slow rate of growth and overall convenience in experimental operations. They have been used in studies involving tumors, cardiovascular diseases, diabetes, oral surgeries, plastic surgeries, hematologic diseases, genetic and metabolic diseases, and drug safety evaluation ( Guo et al, 2015 ). The miniature pig is now beginning to be applied to inner ear studies.…”

Transcript variants and expression profiles analysis of Mitf gene in minipigs

“…Recently, an increasing number of studies have found that mutations of Mitf in minipigs can lead to a variety of coat color phenotypes, hereditary hearing loss and primary melanoma ( Tachibana et al., 1996 ; Nishimura et al., 2005 ). Considering its proximity with humans in evolution, the minipig becomes an ideal animal model in study human diseases ( Guo et al., 2015a , b ). To establish a suitable animal model for further studies into MITF / Mitf functions, the current study aims to identify alternatively spliced transcript variants of porcine Mitf and analyze their expression in different tissues.…”