Recording the Hibernation Peculiarities by Incisor Dentin in Spotted Suslik Spermophilus suslicus (Sciuridae, Rodentia) [Enregistrer les particularités de l'hibernation sur la dentine des incisives du spermophile tacheté Spermophilus suslicus].

Résumé

Longitudinal and transverse ground sections of the upper incisors and sections stained with hematoxylin were analyzed in spotted susliks (Spermophilus suslicus): 59 adults hibernating in nature, ten juveniles trapped in nature and in 17 adults and 11 juveniles kept in laboratory without illumination and heating for 1-7 months (including the hibernation season) and injected with tetracycline (1-6 times, at doses of 10-20 mg/kg of the body weight) to label chronologically the growing sites of dentin. During the euthermal season, the layers were formed in incisor dentin. When entering hibernation in August-September, the contrasting hypo- and hyper-chromatic bands corresponding to hypothermal episodes were formed in dentin; a decrease in the rates of dentin apposition and incisor eruption and a disturbance in the dentinogenesis rhythm occurred. During deep hibernation, in both the natural and experimental conditions, the hibernation zone was formed in dentin. This included the hyperchromatic layers of decreasing width followed by a group of faintly stained narrow layers (3-6 m). The groups of narrow layers were formed in February-March, during the terminal arousal from hibernation and in December during artificially provoked arousal in experiment. In the latter case, dentin apposition and incisor eruption renewed, and the daily rhythm of the dentinogenesis restored, which is evidence for incisor growth during hibernation in nature throughout the spontaneous rhythmic arousals.