Anatomical middle and inner ear parameters are often used to predict hearing sensitivities of mammalian species. Given that ear morphology is substantially affected both by phylogeny and body size, it is interesting to consider whether the relatively small anatomical differences expected in related species of similar size have a noticeable impact on hearing. We present a detailed anatomical description of the middle and inner ears of the red fox Vulpes vulpes, a widespread, wild carnivore for which a behavioural audiogram is available. We compare fox ears to those of the well-studied and similarly sized domestic dog and cat, taking data for dogs and cats from the literature as well as providing new measurements of basilar membrane (BM) length and hair cell numbers and densities in these animals. Our results show that the middle ear of the red fox is very similar to that of dogs. The most obvious difference from that of the cat is the lack of a fully formed bony septum in the bulla tympanica of the fox. The cochlear structures of the fox, however, are very like those of the cat, whereas dogs have a broader BM in the basal cochlea. We further report that the mass of the middle ear ossicles and the bulla volume increase with age in foxes. Overall, the ear structures of foxes, dogs and cats are anatomically very similar, and their behavioural audiograms overlap. However, the results of several published models and correlations that use middle and inner ear measurements to predict aspects of hearing were not always found to match well with audiogram data, especially when it came to the sharper tuning in the fox audiogram. This highlights that, although there is evidently a broad correspondence between structure and function, it is not always possible to draw direct links when considering more subtle differences between related species.

• MeSH
• fylogeneze * MeSH
• kočky MeSH
• lišky anatomie a histologie   fyziologie   MeSH
• psi MeSH
• střední ucho anatomie a histologie   fyziologie   MeSH
• velikost orgánu fyziologie   MeSH
• velikost těla fyziologie   MeSH
• vláskové buňky fyziologie   MeSH
• vnitřní ucho anatomie a histologie   fyziologie   MeSH
• zvířata MeSH
• Check Tag
• kočky MeSH
• psi MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• srovnávací studie MeSH

The red fox (Vulpes vulpes) is the carnivore with the widest distribution in the world. Not much is known about the visual system of these predominantly forest-dwelling animals. The closely related Arctic fox (Vulpes lagopus) lives in more open tundra habitats. In search for corresponding adaptations, we examined the photoreceptors and retinal ganglion cells (RGCs), using opsin immunohistochemistry, lucifer yellow injections and Nissl staining. Both species possess a majority of middle-to-longwave-sensitive (M/L) and a minority of shortwave-sensitive (S) cones, indicating dichromatic color vision. Area centralis peak cone densities are 22,600/mm2 in the red fox and 44,800/mm2 in the Arctic fox. Both have a centro-peripheral density decrease of M/L cones, and a dorsoventrally increasing density of S cones. Rod densities and rod/cone ratios are higher in the red fox than the Arctic fox. Both species possess the carnivore-typical alpha and beta RGCs. The RGC topography shows a centro-peripheral density gradient with a distinct area centralis (mean peak density 7,900 RGCs/mm2 in the red fox and 10,000 RGCs/mm2 in the Arctic fox), a prominent visual streak of higher RGC densities in the Arctic fox, and a moderate visual streak in the red fox. Visual acuity and estimated sound localization ability were nearly identical between both species. In summary, the red fox retina shows adaptations to nocturnal activity in a forest habitat, while the Arctic fox retina is better adapted to higher light levels in the open tundra.

• MeSH
• čípky retiny fyziologie   MeSH
• druhová specificita MeSH
• fotoreceptory obratlovců fyziologie   MeSH
• imunohistochemie MeSH
• lišky fyziologie   MeSH
• lokalizace zvuku fyziologie   MeSH
• oči anatomie a histologie   MeSH
• opsiny metabolismus   MeSH
• retinální gangliové buňky fyziologie   MeSH
• tyčinky retiny fyziologie   MeSH
• vidění barevné fyziologie   MeSH
• životní prostředí MeSH
• zraková ostrost fyziologie   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• srovnávací studie MeSH

We determined the absolute hearing sensitivity of the red fox (Vulpes vulpes) using an adapted standard psychoacoustic procedure. The animals were tested in a reward-based go/no-go procedure in a semi-anechoic chamber. At 60 dB sound pressure level (SPL) (re 20 μPa) red foxes perceive pure tones between 51 Hz and 48 kHz, spanning 9.84 octaves with a single peak sensitivity of -15 dB at 4 kHz. The red foxes' high-frequency cutoff is comparable to that of the domestic dog while the low-frequency cutoff is comparable to that of the domestic cat and the absolute sensitivity is between both species. The maximal absolute sensitivity of the red fox is among the best found to date in any mammal. The procedure used here allows for assessment of animal auditory thresholds using positive reinforcement outside the laboratory.

• MeSH
• akustická stimulace MeSH
• chování zvířat fyziologie   MeSH
• druhová specificita MeSH
• hluk MeSH
• kočky MeSH
• lišky fyziologie   MeSH
• psi MeSH
• sluch fyziologie   MeSH
• sluchová percepce fyziologie   MeSH
• sluchový práh fyziologie   MeSH
• zvířata MeSH
• Check Tag
• kočky MeSH
• mužské pohlaví MeSH
• psi MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• srovnávací studie MeSH

• MeSH
• biomedicínský výzkum MeSH
• buněčné jádro účinky léků   ultrasonografie   MeSH
• folikuly stimulující hormon fyziologie   MeSH
• kyselina okadaová fyziologie   MeSH
• lišky anatomie a histologie   fyziologie   růst a vývoj   MeSH
• meióza fyziologie   účinky léků   MeSH
• oocyty fyziologie   růst a vývoj   účinky léků   MeSH
• růstový hormon fyziologie   MeSH
• skot MeSH
• techniky in vitro MeSH
• zvířata MeSH
• Check Tag
• skot MeSH
• ženské pohlaví MeSH
• zvířata MeSH