In the esophagus, the mucosa collapses against the distal end of the endotracheal tube, thereby limiting the ability to fully pull back on a syringe or for a flexible compressed bulb to reexpand.
In a pennaceous feather, the barbs grow helically around the tubular feather germ and fuse on one side to form the rachis.Simultaneously, new barb ridges form on the other side of the tube.
The only cells it really infects are what we call respiratory epithelial cells, a one-cell layer of cells that kind of protect the breathing tubes and the lungs, all the way down to the bottom, where we have air sacs.
Oh sure, they make a " flap" about that, but it's " plane" to see that the " props" you'd need exceed what's free to take off at speed, and land a record for flying " so low" through a " tube" that is " so low" .
That's also kinda why sticking this cone-shaped piece into a tube is illegal—without a way to know it's clicked into place, you could push it too far and get it stuck forever.