Primordial germ cells (IMAGE) University of Münster Caption Spatial and temporal distribution of primordial germ cells (stained in red) in zebrafish embryos. Normally, with the help of an attractant produced in the environment, the cells migrate in a targeted and coordinated manner through the developing embryo and reach the regions where the sex organs are formed (left). In the absence of the attractant receptor, the cells distribute differently (right). Looking at just one zebrafish, as here, there seems to be no pattern in this. Credit Gross-Thebing, Truszkowski, Tenbrinck et al. Sci Adv 2020;6: eabc5546/CC BY-NC Usage Restrictions The use of any images that may be sent with this press release is permitted exclusively in the above-mentioned context and with reference to the source. License Licensed content 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.