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A whole-embryo culture method which is known as one of the in vitro teratological methods was established in rats. Sprague-Dawley rat embryos were explanted on gestational day (GD) 9.5 and cultured for 48hrs in 15㎖ culture bottles containing 2m1 of culture media consisting of 100% immediately centrifuged and heat-inactivated rat serum. The culture bottles were attached to a rotator drum and rotated at 35rpm, 37.5℃ with a continuous gas flow of 5% O₂, 5% CO₂, 90% N₂ for the first 17hrs; 20% O₂, 5% CO₂, 75% N₂ for the next 7hrs; 40% O₂, 5% CO₂, 55% N₂ for the last 24hrs. After 48hrs of culture, embryos were scored for morphological development according to the procedure of Van Maele-Fabry, and their total protein contents were determined. At the begining of the culture, embryos were in head-fold stage, and the total length of conceptuses including ectoplacental corn was 2.1±0.3mn. At the end of the culture, in vitro growth was comparable to GD 11.5 in vivo growth: in vitro crown-rump length(mm) was 98.1% of in vivo (3.18±0.30 vs. 3.24±0.28, respectively), in vitro head length(mm) was 99.4% of in vivo (1.53±0.17 vs. 1.54±0.12, respectively), in vitro somite number was 99.7% of in vivo (22.36±2.16 vs. 22.42±1.78, respectively), and in vitro protein concentration(㎍) per embryo was 95.3% of in vivo (273.2±32.8 vs. 286.7±25.3, respectively). These results demonstrate that morphology, growth, degree of differentiation, and protein content of in vitro rat embryos are almost identical to those of in vivo embryos and suggest that the whole-embryo culture system can be a useful tool for prescreening teratogenic agents.
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