This is something that we commonly see in my lab, and I've previously featured other examples of banana seeds on this blog. Here are the links to 2 previous posts:
Because I've received some degree of skepticism when I've posted banana seeds in the past, I decided to conduct an experiment to see if I could recreate their appearance through some laboratory digestion techniques. So here was my process:
Step 1. Sacrifice my banana from lunch for the good of science
Step 2. Add bananas to pre-prepared tubes of proteinase K in buffer. (Unfortunately I didn't have any amylase which would have digested the carbohydrates in the banana. However, this was the best I could do to simulate the digestive process). Vortex to mix and then incubate at 56 degrees Celsius while gently shaking (the standard tissue digestion that we use for PCR pre-processing).
Step 3. Check regularly. I first checked every 10 minutes , but very quickly realized that this was going to be a long process. After the first 4 hours, this is how the banana sections looked:
Step 4. Check again, 24 hours later - looking pretty good!
Step 5. Final check - 48 hours. Success! I think that these look nearly identical to our clinical specimen. What do you think?
Again, it's not a perfect match since the actual patient specimen was subjected to the entire gastrointestinal digestive process. However, the strings of immature seeds can clearly be seen. Here is how they look microscopically: