What is Developmental Toxicology? Toxicology is the study of harmful substances. Developmental toxicology is the study of how those substances affect organisms during early stages of growth. In all animals, the development stage begins when an egg is fertilized and lasts until the egg hatches (in the case of zebrafish) or until birth (in the case of mammals like humans and mice.) If an embryo is exposed to a developmental toxin —a chemical that harms a developing organism—it can suffer physical changes (also called morphological changes; “morph“-means shape or form) and become deformed. These developmental toxins change the body’s normal gene expression, or the way the body reads its instructions from genes in DNA.
One powerful analytical tool is the microarray (micro: small, array: arranged in a table). A microarray contains copies of many different genes (DNA) and can measure the type and amount of mRNA (messenger ribonucleic acid) in an organism. With a microarray scientists are able to study many genes at a time. Several organisms, including zebrafish and humans, have been well studied and scientists know where all their genes are and what they do. So they have a better understanding of how organisms are affected by changes in their gene expression.