[Postnatal development of the brain mass in guinea pigs (Cavia cobaya)]

The quantitative development of body mass (BoM) and brain mass (BrM) has been studied in guinea pigs during postnatal life from the 1st day until adulthood. The increase of both the parameters (BoM, BrM) was statistically significant from the 7th day on (p less than or equal to 0.05). The growth curves of BoM and BrM can be described mathematically by non linear regression functions of which the correlation coefficients were r = 0.96 and r = 0.82, respectively. The two growth rates of BoM and BrM show negative allometry, the rate of increase of BoM being 2.45 and that of BrM 1.16 between the 1st day and day 19-25. The correlation coefficient of the BoM/BrM ratio was r = 0.87. During the postnatal brain development of the guinea pig no particular growth spurt could be observed, as it is known from other species, e.g. the rat. This finding seems to be coherent with the advanced state of the newborn guinea pig with his functioning sensory mechanisms and an important motor activity.