Final answer:
Centripetal invagination in Cladophorales refers to the inward folding of the cell membrane, which resembles the formation of a cleavage furrow in animal cell cytokinesis.
Step-by-step explanation:
Cladophorales divide cells via centripetal invagination, which refers to the inward folding of the cell membrane during cytokinesis. This process is similar to the cytokinesis in animal cells, where a contractile ring of actin filaments forms just inside the plasma membrane at the former metaphase plate, pulling the equator of the cell inward to create a fissure known as the cleavage furrow. The furrow deepens as the actin ring contracts, eventually cleaving the cell in two. In contrast, plant cells, which have a rigid cell wall, cannot form a cleavage furrow, so they undergo cytokinesis by forming a cell plate in the center and extending it outward to split the cell. Golgi vesicles coalesce at the former metaphase plate to form this cell plate.
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