Mouse Embryo and Brain (image) Wyss Institute for Biologically Inspired Engineering at Harvard Share Print E-Mail Caption To develop fluorescent in situ sequencing, scientists first fix in place thousands of RNAs -- including working copies of genes called messenger RNAs -- in cells, tissues, organs or embryos. Here, RNAs are labeled red in a mouse brain (left) and green in a mouse embryo (right). Credit Wyss Institute and Harvard Medical School Usage Restrictions Please, credit Wyss Institute and Harvard Medical School. Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.