 Kinetochore-microtubule attachment

Kinetochore-microtubule attachment mechanically links a chromosome to the spindle apparatus through its kinetochore. An end-on attachment can maintain contact with a microtubule while that microtubule grows or shortens. For accurate chromosome segregation, sister kinetochores normally attach toward opposite ends of the spindle apparatus; attachment alone does not establish that this geometry is correct. Incorrect attachments can be released and replaced. ^[ref]

A laser experiment separated an unattached kinetochore from the rest of a chromosome. Destroying the last unattached kinetochore allowed anaphase to begin, whereas control damage to a chromosome arm did not have that effect. This supported an inhibitory signal originating at unattached kinetochores, explaining how even one unfinished attachment can delay the division of the whole cell. ^[ref]