The pinching in of the cell membrane in animal cells during cell division is called cytokinesis.

Here's why:

* Cytokinesis is the final stage of cell division, where the cytoplasm of the parent cell divides into two daughter cells.

* In animal cells, cytokinesis occurs through a process called cleavage furrow formation.

* The cleavage furrow is a groove that forms on the cell surface, gradually pinching the cell membrane inward until the two daughter cells are completely separated.

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