Why don’t fish have tonsils? They have a good alternative, study suggests 
By Mitch Leslie US Source: science 11/1/2023
Mitch Leslie
Credit: Julien Resseguier and Mai Nguyen-Chi
When microbes try to invade our body through the nose or mouth, they have to get past the tonsils, lumps of tissue garrisoned by immune cells that help fight off the intruders. But many animals don’t have obvious tonsils, an apparent gap in their defenses. In Science Advances today, however, researchers report uncovering a comparable organ in fish that may take on a similar immune role.
 

“It’s a very well-done study that convincingly shows there is a tonsil-like structure” in the fish, says immunologist and cell biologist Anna Huttenlocher of the University of Wisconsin-Madison, who wasn’t connected to the research. A second study published today in Science Immunology suggests bony fish—the group that includes trout, zebrafish, and salmon—possess another key part of the human immune system that enables certain immune cells to fine-tune defensive proteins known as antibodies.

 
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