Fruit fly embryo
This composite image of a fruit fly embryo at a very early stage of development helps tell scientists how genes govern an animal’s body plan. Using a confocal microscope and three fluorescently-labeled gene products — one red, one blue and one green — biologists can observe cells as they are told by such genes which part of the animal they are destined to become. Other colors, yellow for example, are produced when more than one gene is at work in a cell. The development of legs, wings, eyes, and antennae are directed by specific sets of genes that are similar in many animals, flies and mice, for example, but produce very different architectures.
This image was produced by Jim Langeland, Steve Paddock and Sean Carroll, all of the Howard Hughes Medical Institute at the University of Wisconsin-Madison.