An examination of blind mole-rat (Nannospalax xanthodon) brain, cerebellum, and spinal cord tissues: A histological and stereological study

Abstract

The purpose of this study was to perform a histological examination of blind mole-rat (Nannospalax xanthodon) brain, cerebellum, and spinal cord tissues. Six blind mole-rats were caught in a natural environment, anesthetized with ether, and sacrificed. Brain, cerebellum, and spinal cord tissues were then removed. All tissues were kept in 10% formaldehyde for one week, at the end of which they were subjected to routine histological procedures and embedded in blocks. Five micron-thick sections were taken from the blocks (5 and 15 micron thick from spinal cord tissues). All sections were then stained with hematoxylin-eosin, Cresyl Violet, and DAPI. These sections were then evaluated under light and fluorescent microscopes. 
 The blind mole-rats weighed 201.3 ± 61 g, the brains and cerebella weighed 1.8 ± 0.3 mg and 0.32 ± 0.05 mg, respectively, and the brain, cerebellum, and spinal cord volumes were 1.49±0.46 ml, 0.33± 0.08 ml, and 2.53± 0.19 µm3, respectively. No histological variation was observed in the brain or cerebellum tissues. However, examination of the spinal cord tissue revealed differences compared to humans and other rodents. The spinal cord exhibited a segmented, lobulated appearance, each lobe itself exhibiting the characteristics of a small spinal cord. No butterfly appearance was observed, and white and gray matter transitions were irregular, with less white and more gray matter. The location of the anterior and posterior horns was unclear. The motor neuron cells were also small in size. No significant variations were observed at nuclear organization (DAPI signals) between any tissues.
 In conclusion, the blind mole-rats were normal in weight, increased brain and cerebellum tissue weight and volumes were observed, while a decrease was determined in spinal cord tissue volumes. The brain and cerebellum were normal at histological examination, while structural differences were detected in the spinal cord.