MORPHOMETRIC AND BIOCHEMISTRY PARAMETERS AS AGE INDICATORS IN THE NORWAY RAT (RATTUS-NORVEGICUS BERK, 1769)

Determination of both morphometric and biochemical parameters as a function of age in the Norway rat has demonstrated that dry tissue weight of the eye lens pairs enables estimation of age in animals from one to approximately 22 months of age. Tyrosine content in the insoluble eye lens fraction, body weight and ratio of body length and weight enable the estimation of age from one to about 10 or 5 months of age, respectively. Body weight of animals at the time of early adulthood (at about 75 days of age) was about 190g for males and 165g for for females. The ratio of body length and weight averaged 0.96 for males and 1.09 for females, while dry tissue weight of the eye lens pairs was about 14 mg and tyrosine content in the insoluble fraction of the eye lens was around 1320 mu g for animals of both sexes.