Objective: Blind mole rats (Nannospalax xanthodon Nehring, 1898) are subterranean mammals that are well-known for their high tolerance to hypoxia and resistance to cancer. Due to their unusual habitat, these animals have developed several adaptations during their evolution. Therefore, this study aimed to identify possible structural differences in Nannospalax visual system in comparison to other mammals that might have arisen as a result of adaptation to underground life. Method: Six blind mole rats were used in the study. No procedure was performed on the rats. After the animals were anesthetized with ether, their eyes and optic nerves were removed. For this purpose, pseudo-eyes and optic nerves were harvested and fixed in 10% formaldehyde for a week. Tissues were embedded into paraffin and blocked via routine histological procedures. Five micrometer sections in thickness were taken and stained with Hematoxylin & Eosin (H&E) and Cresyl Violet. Results: Histopathological analysis of the eye revealed the presence of cornea, retina, sclera, iris, zonula adherens, lacrimal gland and ducts, fatty tissue, muscle layer and the vascular structures. No pathology was observed of optic nerve. Conclusions: We found that the visual system of N. xanthodon share some similarities with other blind mole rat species from Israel, while some histological properties were defined by our study for the first time in the literature.
___
1. Nevo E, Filippucci MG, Redi C, et al. Chromosomalspeciationandadaptiveradiation of molerats in AsiaMinorcorrelatedwithincreasedecologicalstress. ProcNatlAcadSci U S A.1994; 91: 8160-4.
2. Nevo E, Filippucci MG, Redi C, et al.Karyotypeandgeneticevolution in speciation of subterraneanmolerats of thegenusSpalax in Turkey. BiologicalJournal of theLinneanSociety. 1995; 54: 203-29.
3. Savic IR andNevo E. TheSpalacidae: evolutionaryhistory, speciation, andpopulationbiology. In: Nevo, E. ve Reig, O.A. (eds). Evolution of SubterraneanMammals at theOrganismalandMolecularLevels. Wiley-Liss, New York,1990, pp. 129-54.
4. Kryštufek B, Ivanitskaya E, Arslan A, et al.Evolutionaryhistory of molerats (genusNannospalax) inferredfrommitochondrialcytochrome b sequence. Biol. J. Linn. Soc. 2012; 105: 446–55.
5. Hadid Y, Nemeth A, Snir S, et al. Is Evolution of BlindMoleRatsDeterminedbyClimateOscillations. PLoS ONE. 2012: 7.
6. Ivanitskaya E, Coşkun Y, Nevo E. Bandedkaryotypes of molerats(Spalax, Spalacidae, Rodentia)fromTurkey: A comparativeanalysis. J. Zool. Syst. Evol. Research. 1997; 35: 171–7.
7. Kankılıç T, Çolak E, Kankılıç Tol. Macro- Anatomicalandkaryologicalfeatures of twoblindmoleratsubspecies (Rodentia: Spalacidae) fromTurkey. AnatomiaHistologiaEmbryologia. 2009; 38: 145–53.
8. Nevo E. Stress, adaptation, andspeciation in theevolution of theblindmolerat, Spalax, in Israel. Mol. Phylogenet.Evol. 2013;66: 515–25.
9. Nemec P, Cvekova P, Burda H, et al. Visual systemsandthe role of vision in subterraneanrodents: Diversity of retinalpropertiesandvisualsystemdesigns. In: Begall S, Burda H, Schleich CE, eds. Subterraneanrodents: News fromunderground. Heidelberg: Springer. 2007; pp.129–60.
10. Burda H. Earandeye in subterraneanmole-rats, Fukomysanselli (Bathyergidae) andSpalaxehrenbergi (Spalacidae): progressivespecializationorregressivedegeneration ? Anim.Biol. 2006; 56: 475‒86.
11. Sanyal S, Jansen HGJ, de Grip W, et al. Theeye of theblindmolerat, Spalaxehrenbergi. Invest. Ophthalmol. Vis. Sci. 1990; 31: 1398–404.
12. Duebel HP, Romaniuk P, Tschapek A. Model studies on castspecimens of human right ventricles. CorVasa. 1984; 26: 210-9.
13. Aktürk Z, Odacı E, İkinci A, et al.Effect of Ginkgobiloba on brain volum eafter carotid artery occlusion in rats: a stereological and histopathological study. Turk J MedSci. 2014; 44: 546-53.
14. Keleş Aİ. Sağlık Alanında Kullanılan Kantitatif Yöntem, Stereoloji. Dicle Tıp Dergisi / Dicle Med J. 2019; 46: 615–21.
15. Nevo E. Mosaic Evolution of Subterranean Mammals: Tinkering, Regression, Progression, and Global Convergence. In: Begall S, Burda H, Schleich CE, eds. Subterranean rodents: News fromunderground. Heidelberg: Springer. 2007; pp. 375-88.
16. Rado R, Bronchti G, Wollberg Z, et al. Sensitivitytolight of the blind mole rat: behavioral and neuroanatomical study. Isr J Zool.1992; 38: 323- 31.
17. Hetling JR, Baig-Silva MS, Comer CM, et al. Features of visualfunction in thenakedmoleratHeterocephalusglaber. J CompPhysiol A. 2005; 191: 317–730.
18. Wegner RE, Begall S, Burda H. Lightperception in “blind” subterranean Zambianmole-rats. Anim Behav. 2006; 72: 1021–4.
19. Cernuda-Cernuda R, DeGrip WJ, Cooper HM, et al. The retina of Spalaxehrenbergi: novelhistologicfeaturessupportive of a modifiedphotosensory role. Invest Ophthalmol VisSci. 2002; 43: 2374-83.
20. Dureau P, Bonnel S, Menasche M, et al. Quantitativeanalysis of intravitrealinjections in therat. CurrEyeRes. 2001; 22:74-7.
21. Maden A. Anatomi, fizyoloji, lakrimal sistem, Oküloplastik cerrahi. Özden Ofset. İzmir, 1995; 16- 21, 279-297.
22. Duman S. Lakrimal sistem hastalıkları, Temel göz hastalıkları. Güneş Kitabevi. Ankara,2001; pp. 479- 500.
23. Herbin M, Rio JP, Repérant J, Cooper HM, et al. Ultrastructuralstudy of theopticnerve in blindmolerats (Spalacidae, Spalax). VisNeurosci. 1995; 12: 253-61.