Final answer:
Cells in animals differentiate into specialized tissues, such as nervous, muscle, connective, and epithelial, which perform specific functions. Differentiation is controlled by unique genetic expression, with stem cells facilitating the development of the diverse cell types.
Step-by-step explanation:
In all animals except sponges, cells differentiate into specialized tissues, which are groups of cells that take on particular functions in the animal's body. Differentiation is a vital process whereby an unspecialized cell becomes specialized to perform specific roles. As multicellular organisms, animals have various cell types, each with distinct structures and functions.
Specialized cells in the human body are structured in ways that support their unique functions. For instance, muscle cells differ from nerve cells, which are both different from skin cells. These cell types are organized into tissues like nervous, muscle, connective, and epithelial, each performing essential tasks within the organism, such as transmitting nerve impulses or contracting to facilitate movement.
Cellular differentiation is guided by the unique genetic expression of each cell type, allowing cells to 'read' only the parts of the DNA necessary for their specialized functions. Stem cells play a crucial role in development by continually dividing and having the potential to differentiate into any cell type under certain conditions, thus contributing to the diversity of specialized cells and tissues in an animal's body.