Distribution of Uterine Blood Flow

摘要

Normal blood flow patterns were characterized in individual CD rats, nonpregnant (NP) or on day 6, 7, 8, 10, 11, 12, 13, 16, 18, 20 of gestation using the radioactive microsphere technique. Five animals were evaluated at each stage of pregnancy. Weights and flow values were determined for several maternal organs and uterine tissue samples. Embryo/fetal sex was determined from day 11 on from the incidence of nuclei with sex chromatin in amnion smears. There was a marked increase in absolute flow to the uterus and all uterine contents over gestation. However, relative blood flow decreased by day 20 to one-third NP values. Using a nested analysis of variance procedure to evaluate intrauterine weight and blood flow parameters, nearly all showed a highly significant litter effect (p < .001). This interlitter variability in E/F weight and blood flow was observed consistently across gestational stages. Differences in litter size and distribution within the two uterine horns did not account for the majority of the variability. As these parameters vary so remarkably in the normal rat pregnancy, the evaluation of potential 'litter' effects appears a necessity in any teratologic investigation using the rat.