When mice in Patricia Hunt's laboratory at Washington State University began losing fetuses with severe birth defects (facial deformities and absence of hindquarters) or were unable to reproduce, Hunt immediately began searching for the cause.She had seen similar mysterious events before.Years earlier in her old laboratory in Ohio, mouse eggs and fetal chromosomes began to divide in unusual ways. This created genetic errors that could lead to Down syndrome and other chromosome-related disorders.Hunt and her team eventually attributed the cause of these genetic changes to a new cleaning method that wore out the polycarbonate cages where the animals were kept....