Senescent cells secrete damaging chemicals as they accumulate in the body, usually as people enter their 60s.

As the cells secrete cytokines, these proteins are captured by the nearby plate-bound antibodies.

Mast cells secrete it during the anaphylactic reaction, inducing inflammation.

Of the billions of cells in the human brain only about 10,000 to 20,000 cells secrete hypocretin molecules.

The cells secrete individual gelatinous sheaths which can often be seen as sheaths around recently divided cells within outer sheaths.