[Effect of growth hormone on fetal and placental growth of spontaneous dwarf rat].

The effect of growth hormone on fetal and placental growth was studied in the spontaneous dwarf rat (SDR). The SDR is a newly established experimental model for pituitary growth hormone (GH) deficient dwarfism with an autosomal recessive mode of inheritance. The growth of heterogenic fetuses which were made by crossing female SDRs with normal male rats was similar to that of homogenic SDR fetuses on day 16 of gestation (Day 16), but on Day 20 heterogenic fetuses which had GH in their serum were significantly heavier than homogenic fetuses. There was no significant difference between the two groups in placental weight. The daily infusion of ovine-GH into pregnant SDR caused a significant increase in placental weight on Day 20, but had no effect on fetal growth. These results suggest that fetal GH plays a role in the fetal growth without affecting placental growth, and that maternal GH affects placental growth without affecting fetal growth.