A Petri dish is a shallow dish that is used to culture microorganisms. By mixing different ingredients, such as blood, salts, amino acids or bacteria, together with an agar (or medium), scientists are able to observe reactions and watch microorganisms grow and develop.
The Petri dish is an artificial habitat where microorganisms and the nutrients they need to survive are put together. This process, called culturing, allows scientists to experiment and observe the reactions and the growth of these organisms. Besides being indispensable as laboratory equipment, Petri dishes are also used to teach students about important biological concepts.
The Petri dish was invented by J. R. Petri during the 19th century. Although the first dishes were made out of glass, modern Petri dishes are typically made out of plastic or other synthetic materials. Glass varieties are still available from specialty retailers. In fact, there are now 3D Petri dishes that have micromolds to maximize cell-to-cell interactions. The new Petri dishes make it possible to observe different kinds of cells on the same dish. They also allow for production of uniform spheroids and provide control over the spheroid sizes. For stacking and storing, petri dishes are available with a metal ring on the bottom that creates separation between the dishes.