The phrase "a bit of tissue" is correct and usable in written English.
It can be used when referring to a small piece or amount of tissue, often in a biological or medical context.
Example: "The doctor took a bit of tissue for the biopsy to analyze for any abnormalities."
Alternatives: "a small piece of tissue" or "a fragment of tissue."
On the three occasions he left his room, Snowden put a glass of water behind the door next to a bit of tissue paper.
The researchers captured at least 150 rats in each city, snipped off a bit of tissue and probed the samples for 15,000 genetic markers.
In the last three years, we've gotten connectomics, where people are taking a bit of tissue and mapping every connection in it.
The best way to diagnose this disorder now is to extract a bit of tissue from the liver and check it for excess iron a procedure that is both painful and potentially dangerous.
A researcher in a lab at Hopkins swung open a freezer door and showed the daughter, Deborah Lacks-Pullum, thousands of vials, each holding millions of cells descended from a bit of tissue that doctors had snipped from her mother's cervix.
A bit of tissue paper did the trick though - I think I got away with it!
They have to have a bit of connective tissue and a bit of meat".
The two-plus-hour version of the movie that's showing in theatres has longueurs that invite the mental version of clipping one's nails, but the half-hour supercut of the movie's best action scenes and a bit of connective tissue would be an anthology to remember.
If Scott finds himself in contention, he will have to overcome a bit of scar tissue.
When a tiny bit of tissue was transplanted in an unformed newt embryo, it induced the formation of a second embryo, an embryo within an embryo.
It is diagnosed by removing a small bit of tissue from the edge and examining it under a microscope.
