Apoptosis

Tap the cell to watch it take itself apart, step by step.

Apoptosis is a cell's tidy, programmed death: the body's way of removing cells it no longer needs, or that are damaged, without harming their neighbors. Tap and the cell shrinks and its chromatin condenses into a small, dark nucleus (pyknosis). The membrane bubbles out in blebs, the nucleus breaks into pieces (karyorrhexis), and the cell comes apart into apoptotic bodies, each wrapped in membrane, which are cleared away.

Unlike a cell that bursts, nothing spills out, so there is no inflammation. In the body, white blood cells eat the bodies; here they drift away and a neighbor moves in.

The splash shows the stages of apoptosis as a pathology review describes them: shrinkage, condensed chromatin, blebbing, a broken-up nucleus and membrane-bound apoptotic bodies. The clearing of the bodies and the neighbor that moves in are simplified.

1. Correct

   Early in apoptosis the cell shrinks and its chromatin condenses (pyknosis).¹

   The whole cell scales down to 82 percent; the nucleus shrinks and darkens as a condensed copy fades in.

2. Correct

   The plasma membrane blebs, then the nucleus breaks up (karyorrhexis) and the cell separates into apoptotic bodies.¹

   Two sets of blebs bulge in turn; the nucleus is replaced by four dark pieces; the membrane pinches into seven spheres that become solid pieces.

3. Correct

   Apoptotic bodies are wrapped in intact membrane and hold tightly packed organelles, some with a piece of the nucleus.¹

   Each body is a membrane shell with the mitochondria and vesicles that were in its part of the cell; the middle one holds the nuclear pieces.

4. Simplified

   The bodies are cleared by phagocytes, with essentially no inflammation.¹

   The bodies drift away out of view; the About text says white blood cells eat them.

1. 1Apoptosis: a review of programmed cell death (Toxicologic Pathology 35:495-516, 2007), S. Elmore, via PubMed Central

Simplified

The cell is a diagram: a few mitochondria and vesicles stand for its organelles.

Simplified

The blebs come and go in two alternating sets, as a regular pattern.

Simplified

The bodies drift away rather than being eaten, and a neighbor of the same kind moves in, so the splash can play again.

Simplified

Apoptosis takes minutes to hours; the splash takes about 14 seconds.

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