English: The zebrafish embryo begins as a yolk with a single enormous cell on top (0 h), which divides into two (0.75 h) and continues dividing until there are thousands of small cells (3.25 h). The cells then migrate down the sides of the yolk (8 h) and begin forming a head and tail (16 h). The tail then grows and separates from the body (24 h). The yolk shrinks over time because the embryo uses it for food as it matures during the first few days (72 h). After a few months, the adult fish reaches reproductive maturity. Photos approximately to scale except adult, which is approximately 2.5 cm long.