THE DENTIN OF INCISORS IN RODENTS AS A RE CORDING STRUCTURE

The dentin of incisors of Apodemus sylvaticus, Citellus pygmaeus and C . undulatus was studied to reveal the influence of long-term growth cy cles on the formation of daily layers. The decrease of body growth rat e with age causes the decrease of the width of daily layers of dentin. The winter retardation of body growth is recorded in non-hibernating rodents by the decrease of the width of daily dentin layers, and in hi bernating ones - by the formation of tile atone of hibernation>> in th eir incisors. The pattern of <<the zone of hibernation>> in Citellus i s different from that in Sicista due, probably, to the differences in the mode of hibernation. In the females of Citellus, the period of lac tation is recorded as a ring of dentin deeply stainable by haematoxyli n.