Javad Sadeghinezhad - Department of Basic Sciences, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran
Margherita De Silva - Department of Veterinary Medical Sciences, University of Bologna, Bologna, Italy
Mahdi Aghabalazadeh Asl - Department of Basic Sciences, Faculty of veterinary Medicine, University of Tehran, Tehran, Iran
Ava Saeidi - Department of Basic Sciences, Faculty of veterinary Medicine, University of Tehran, Tehran, Iran
Nadia De Sordi - Department of Veterinary Medical Sciences, University of Bologna, Bologna, Italy
Roberto Chiocchetti - Department of Veterinary Medical Sciences, University of Bologna, Bologna, Italy

Background and Aim : The involvement of the cerebellum in motor coordination has been long and widely recognized; however, a growing body of evidence involving neuroanatomical and clinical studies indicates that it plays a significant role in non-motor behavioral-affective and cognitive functions. Most stereological investigations on the cerebellum involving laboratory animals have been carried out on mice and rats; however, the morphometric features of the normal cerebellum in adult guinea pigs have not been previously investigated using stereology. Guinea pigs have proved useful as experimental animal models in studying cerebellar anatomical and structural alterations in human neurological disease, due to several similarities shared between the two species. Recently, however, increasing interest has been addressed toward the clinical features, pathological changes and therapeutic resolution of neurological disorders of guinea pigs held as pet animals. Several infectious diseases such as lymphocitic choriomeningitis virus (LCMV) and Toxoplasma gondii, for instance, have been described to cause predominant involvement of the cerebellum. The objective of the present work was to establish normal volumetric and quantitative stereological parameters for cerebellar tissues in adult guinea pigs, by means of unbiased design-based stereology. Specifically, the present study was designed to estimate cerebellar total volume, grey and white matter, molecular and granular layers volume fractions, and cerebellar surface area in the guinea pig.Methods : Cerebella from six adult male guinea pigs were excised and divided into the two hemispheres. Each half was randomly chosen, weighed, routinely processed for light microscopic examination and subsequently embedded in paraffin. Isotropic, uniform random sections were obtained by applying the orientator method. Sections were stained with Cresyl violet 0.1 %. A slide scanner was employed for capturing images from sections in order to enable the estimation of cerebellar total volume, white matter (WM) and gray matter (GM) volume fractions, molecular and granular layers fractional volumes using Cavalieri ‘s principle and the point counting system.Results : The total volume of a guinea pigs cerebellar hemisphere was 0.11±0.01 cm3. The mean relative volume fractions of the GM and WM were 78±2.6% and 22±2.6%, while their mean total volumes were found to be 0.21±0.02 cm3 and 0.059±0.006 cm3, respectively. The volumes of the molecular and granular layers were estimated to be 112.41±20.5 mm3 and 104.3±7.3 mm3, while their mean thickness was calculated to be 0.184±0.02 mm and 0.17±0.01 mm, respectively. Conclusion : The morphometric data emerging from the present study may provide an accurate set of reference data potentially valuable as basic anatomical contribution to the field of veterinary neurology when examining pathological changes in response to neurological disease, and may also find a use as an animal anatomical model for comparison with human cases.

Guinea Pig; Cavia porcellus; cerebellum; stereology; neurology