Seasonal Variability of the Hippocampus’s Architectonics in Bank Voles (Clethrionomys glareolus, Rodentia)
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Seasonal and age-related variability of the hippocampus in the bank vole (Clethrionomys glareolus) was monitored in a natural population from Moscow oblast. Autumn-born animals were compared at three stages of their life cycle: in autumn (1–3 months old), during the winter decrease of brain weight (5–7 months old), and after the spring “growth spurt” (9–11 months old). The winter sample exhibited significantly smaller (p < 0.05) section areas of both the dentate gyrus and the CA3 field of the hippocampus. All studied divisions of the hippocampal complex—molecular and granule layers of the dentate gyrus, pyramidal cell layers, and fibers of the CA3 field of the hippocampus—exhibited a similar winter decrease (9.4–13.3%). In spring, hippocampal complex showed regrowth. In overwintered voles, the size of hippocampal divisions in summer surpassed that in the winter sample by 5.4–27.3%. The results indicate a considerable morphological plasticity of the main hippocampal structures in response to seasonal factors in nonwinter-sleeping rodents.
Keywords:hippocampus dentate gyrus architectonics morphological plasticity seasonal variability bank vole.
I am grateful to N.A. Ushakova, a researcher at A.N. Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, for help with computer processing of morphometric data.
This work was conducted under the State Assignment “Studies of Vertebrate Animal Adaptations with Methods of Comparative and Functional Morphology,” part 2 (CITIS no. АААА–А16–116021660071–1).
COMPLIANCE WITH ETHICAL STANDARDS
Research was conducted in compliance with ethical standards established by the Bioethics Committee of Moscow State University.
CONFLICT OF INTEREST
The author declares no conflict of interest.
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