Introduction: Cellular Structure and Function
All organisms are made of cells. Complex organisms (such as humans) are made up of collections of highly specialized cells, each with its own specific function. Different types of cells have evolved specific shapes and properties which help them do their jobs inside the organism.
Heart cells grown from mouse embryonic stem cells - movie 1
These beating cardiac myocytes (heart cells) were grown from mouse embryonic stem cells.

The movie is shown in real time.
Cardiac myocytes were cultured from pluripotent mouse embryonic stem cells using standard techiniques. For imaging, cell aggregates were transferred to small, sterile plexiglass chambers attached to a coverslip, containing differentiation media. Cells were maintained on an inverted compound microscope in an environmental chamber kept at 37°C, 7.0% CO2. Images were taken with a 40x phase contrast objective and a digital video camera.