A longitudinal radiographic study of the growth of the rat skull.

The growth of the skull of the rat was longitudinally from 23 to 140 day PC from radiographs. Four measurements were made on each animal at each age studied. The velocity graphs of these measurements showed that for two, namely neurocranium length and bizygomatic width, the peak rate of growth occurred before birth. Viscerocranium length and neurocranium width showed peak rates after birth. Males became significantly larger than females in each of the absolute measurements studied, but in cranial index and facial index there were no significant differences between the sexes. Both these indices showed strain differences when compared to the results obtained by other workers.