Cell differentiation is the process by which a less specialized cell goes through development and maturation in order to become more distinct in terms of form and function.The cell size, shape, polarity, metabolism and responsiveness to signals change dramatically during differentiation.These changes are brought about by modification in gene expression.Switching off of many genes can occur without changing sequence of DNA.
In multicellular organisms, a single zygote develops into a complex system of tissues and cells.In adults, stem cells divide and create fully differentiated daughter cells during tissue repair.
A cell which can differentiate into many cell types is known as' pluripotent". Such cells are called stem cells in animals and meristematic cells in higher plants.
A cell that can differentiate into any cell type is called" totipotent" cell.In animals, zygote and a few early embryonic cells are totipotent, while in plant any cell can be modified to become totipotent by an external stimulus.