Observation of marking-like behavior, marking behavior and growth of the scent gland in young Mongolian gerbils (Meriones unguiculatus) of an inbred strain

A marking-like behavior (defined by authors), a marking behavior, and growt h of the scent glands were observed in young Mongolian gerbils of an inbred strain. In males and females, a marking-like behavior, in which animals ru b their abdominal scent glands on the floor, began to be seen at the age of 19 days and could be seen in almost all the gerbils at 22 days of age duri ng the suckling period. The frequency of this behavior was highest at 60 da ys of age (males: 17.9/10 min, females: 15.4/10 min) and there was no sex d ifference. Marking behavior, in which animals rub their abdominal scent gla nds on small protruding objects, began to be seen at the age of 40 days in males and 50 days in females. The frequency of this behavior tended to incr ease until 90 days of age in males (13.7/10 min), but the levels were low ( 2.5-5.0/10 min) in females. The values in the male group therefore tended t o be higher than that in the female group. Macroscopic scent gland pads wer e clearly observed at the age of 30 days in males, but not until 45 days of age in females. At the age of 45-90 days, the length of the scent gland pa d in males and females was 2.1-2.8 and 1.6-1.7 cm, respectively and the wid th was 0.3-0.5 in males and 0.2-0.3 cm in females. During this period, the length and depth of the pads in males were significantly greater than those in females (p<0.05). Histological examination of the structure of the scen t glands after the age of 45 days showed that the development of clusters o f acinar cells in females occurred much later than that in males, but the b asic structure of these glands was similar in both sexes. These results sug gest that the marking-like behavior was manifested although during the peri od when the scent glands had not yet developed, whereas true marking behavi or first occurred when the glands were moderately well developed.