I compiled the following set of microscopy images to teach an undergraduate student how to recognize mitotic phases.
They represent fixed HeLa cells whose DNA has been stained with Hoechst; the cells express a GFP-CENP-A fusion protein, which localizes to the centromeres (giving the green dots staining).
A PDF version (one A4 page) of this note is also available.
|Early prophase; condensation of chromosomes begins.|
|Late prophase: chromosomes are fully condensed and form a circle in the (disappearing) nucleus.|
|Prometaphase; the circle opens as chromosomes are mobilized to form the metaphase plate (congression).|
|Metaphase; chromosomes are aligned on the metaphase plate.|
|Abnormal metaphase; one or several chromosomes failed to align in the metaphase plate.|
|Metaphase-to-anaphase transition (late metaphase); the distance between centromeres increases.|
|Early anaphase; chromosomes start moving towards the poles (segregation).|
|Mid-anaphase; chromosomes now form two distinct shapes.|
|Late anaphase; the gap between the two sets of chromosomes widens.|
|Abnormal anaphase; presence of lagging chromosomes (or chromosome fragments) between the two sets of migrating chromosomes.|
|Telophase; the two chromatin shapes become larger as the chromosomes begin to decondensate.|
|Abnormal telophase; presence of a “chromatin bridge” (partial or completeà between the two sets of chromosomes.|
|Cytokinesis; chromosomes are decondensed; chromosomal passenger proteins (red, Aurora B kinase) concentrate on the midbody between the two newly formed nuclei.|