Answer:
when vesicles cluster at the future plane of division
Step-by-step explanation:
Cytokinesis is the process whereby the cytoplasm of a cell divides into two. This process of cytokinesis occurs after nuclear division i.e. division of the nucleus. However, cytokinesis differs in plant and animal cells.
In plant cells, the separation of the cytoplasm involves the formation of a cell plate. The process begins when a structure called phragmoplasts carry vesicles to the cell plate. In other words, vesicles cluster at the future plane of division (cell plate).