Lack of effect on body weight and content of nitrogen and fat after insulin administration to fetal rats.

The effect of fetal insulin injection on body weight and carcass lipid and nitrogen content was studied in four groups of rat fetuses. In each litter, one fetus in each horn was randomly chosen for treatment with either insulin injection, saline injection, insulin solvent injection or sham operation. Injections were given subcutaneously to the fetuses on days 18 1/2, 19 1/2, and 20 1/2 of gestation. The experimental model and the statistical evaluation took into consideration the influence of the fetal position in the uterine horn as well as the variability of fetal size between different litters. Using this experimental model we found that insulin injections to the fetal rat had no effect on body weight and body composition.