Totipotent cells are unique types of stem cells that have the ability to develop into any cell type in an organism, including both the embryonic and extra-embryonic tissues. This means they can form all the different cell types needed for a complete organism, such as skin, muscle, and even the cells that make up the placenta. These cells are typically found in the earliest stages of development, specifically in the first few divisions of a fertilized egg. After a few divisions, cells begin to specialize and lose their totipotency, becoming pluripotent or multipotent cells, which can only develop into certain types of cells.