Developmental staging and thalidomide teratogenicity in the green monkey (Cercopithecus aethiops)

The developmental stages of 11 Cercopithecus aethiops embryos, 24 to 45 days post-mating, are described. The onset of organogenesis in this species is approximately five to seven days later than that reported for macaques and baboons. This temporal difference in the embryonic period is an important factor in the analysis of the subsequent teratogenic study. Oral administration of thalidomide in single or multiple (3-day) treatment periods to pregnant green monkeys between days 28 and 33 resulted in defects of the limbs which resemble those observed in macaques and baboons. However, the sensitive period occurs approximately four days later than that reported for another nonhuman primates. These results indicate that the sensitive period of the limbs to thalidomide coincides with their earliest development.