Zebrafish (Danio rerio) is a favorite model for studying development, in part because its transparent embryos make it possible to produce an ever-growing array of amazingly informative images. For one recent example, check out this Federation of American Societies for Experimental Biology’s 2016 BioArt winner, which shows the developing face of a 6-day-old zebrafish larva.
Yes, those downturned “lips” are indeed cells that will go on to become the fish’s mouth. But all is not quite what it appears: the two dark circles that look like eyes are actually developing nostrils. Both the nostrils and mouth express high levels of F-actin (green), a structural protein that helps orchestrate cell movement. Meanwhile, the two bulging areas on either side of the fish’s head, which are destined to become eyes and skin, express keratin (red).
Oscar Ruiz, who works in the lab of George Eisenhoffer at The University of Texas MD Anderson Cancer Center, Houston, used a confocal microscope to create this image. What was most innovative about his work was not the microscope itself, but how he prepared the sample for imaging. With traditional methods, researchers can only image the faces of zebrafish larvae from the side or the bottom. However, the Eisenhoffer lab has devised a new method of preparing fish larvae that makes it possible to image their faces head-on. This has enabled the team to visualize facial development at much higher resolution than was previously possible.