The major differences in plant and animal cell division are in the assembly of the spindle apparatus. The site of spindle apparatus assembly is the centrosome. In animal cells, a pair of centrioles is at the center of the centrosome. In contrast, most plants lack centrioles, but they do have a centrosome. In animal cells, a cleavage furrow forms during cytokinesis, which deepens and then pinches the parent cells in two. Plant cells, which have cell walls, do not have a cleavage furrow. Instead, a cell plate is produced in the middle of the parent cell, which grows toward the perimeter of the cell until it reaches the plasma membrane, dividing the cell in two. A new cell wall then forms from the cell plate.