INFLUENCE OF THE ENVIRONMENT ON THE UNBORN.

EMBRYONIC DEVELOPMENT IS INFLUENCED BY THREE ENVIRONMENTS: the intra-uterine, the maternal body and the maternal surroundings. Factors present in one or other may cause abnormal development.Usually environmental factors act in association with genetic factors but they can be the dominant or sole cause of birth defects. Many malformation-producing agents exist in the maternal environment and some cause abnormalities in man. Use of such agents in experimental animals yields valuable information on how malformations develop. Different species and strains of animals often react differently to the same teratogenic agent, leading to difficulties in screening substances which may be harmful to human embryos. Laboratory experimentation, detailed study of human abortion material and the vigilance of the physician are all essential in the search for human teratogens.