Relation between body weight, growth rate, chronological age and puberty in male and female rats

Body weight, growth rate, chronological age and puberty in female and male rats from litters of 8 and 12 offsprings/mother have been studied. Age and body weight at the moment of vaginal opening (VO) and balanopreputial separation (BPS) were analyzed. Results show that animals reared in smaller groups grew faster than others. After weaning there was an increase in growth rate. VO and BPS occurred at the same age in groups with different growth rates and different body weights. In conclusion this work evidences that external signs of sexual maturation are not linked to a "critical weight" or to a "growth rate".