T. Futatsuki et al., CHANGE OF DENTIN FORMATION DURING THE REPRODUCTIVE-CYCLE IN MICE, Journal of craniofacial genetics and developmental biology, 15(1), 1995, pp. 51-56
The volume of incisor dentin formation was investigated semi-longitudi
nally using the time-marking method during the reproductive cycle of p
regnancy, parturition, lactation, and post-weaning in mice, and was co
mpared with unmated, non-pregnant control mice. DDD/Qdj mice were inje
cted with nitrilo-tri-acetate lead acid solution subcutaneously at 4-d
ay intervals. Serial cross sections of 100 mu m thickness were prepare
d from the edge of the tooth to the apical portion. Each area of denti
n, encircled by adjoining lines labeled with the lead that was formed
at 4-day intervals, was measured by means of an image scanning system.
The total amount of dentin formation per 4-day intervals was quantifi
ed as a volume in all animals. In the control animals, there was no si
gnificant difference at each period throughout the experiment. However
, the volume of dentin formation increased during the reproductive cyc
le over that of the control. The increase in volume was significant (P
< 0.0001). In addition, during pregnancy, the volume increased gradua
lly with the greatest increase seen in the last 4 days of pregnancy, i
ncluding the day of parturition, as compared with the first half-term
of pregnancy (P < 0.05). The volume decreased immediately after partur
ition as compared with the latter half-term of pregnancy (P < 0.05). T
he results of the present study suggest that the volume of dentin form
ation is affected by the change of maternal metabolism during the repr
oductive cycle in mice.