The beginnings of zebrafish research can be traced back to early 1930s when Charles Creaser at Wayne State University in Detroit began using zebrafish (Danio rerio) eggs to show students the development of a live embryo and the movement of blood inside its arteries. Creaser was able to do this because zebrafish females release eggs from their body which are fertilized by the sperm released from the male. The freshly formed embryo is accessible to the observer from the moment it is fertilized. The fact that zebrafish embryos and larvae are transparent means studying the internal parts of the animal is a breeze. Creaser established methods for rearing, feeding and breeding zebrafish in the lab, but widespread use of the animal did not take off for another three decades.