title: Effect of exposing mice to 50 ATA helium pressure at different stages of pregnancy.
abstract: Pregnant T-O mice were exposed to 50 ATA He-O2 pressure for 4 days at different stages of gestation: 4-7, 6-9, and 9-12 days gestation. Controls were exposed to 1 atmosphere absolute (ATA) air. After the exposure period, pregnancy continued until 18 days gestation when the mice were killed and autopsied. Data were collected relating to the litters and placentas (Litter size, percent resorptions, placental weight, fetal-to-placental ratio) and fetuses (weight, crown-rump length, sex, skeletal abnormalities) and analyzed using analysis of variance. Results showed a small but significant increase in the percent resorptions in the pressure group and also a decrease in crown-rump length and placental weight. None of these changes were related to the stage of gestation in which the mice were exposed. No teratogenic effects of pressure were seen. We conclude that exposure to 50 ATA He-O2 during pregnancy in mice produces a small nonselective effect on fetal growth and development but does not affect any specific event taking place during these stages of embryogenesis.
mesh_terms: D000818:Animals; D005260:Female; D005327:Fetal Resorption / Q000503:physiopathology; D005333:Fetus / Q000187:drug effects*; D006371:Helium / Q000494:pharmacology*; D051379:Mice; D008815:Mice, Inbred Strains; D009929:Organ Size / Q000187:drug effects; D010920:Placenta / Q000033:anatomy & histology / Q000187:drug effects; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000187:drug effects*
chemical_list: D006371:Helium