Situs Inversus
All of us Anatomy TAs were freaking out yesterday, excited to see a situs inverus cadaver. (Situs inversus occurs when all your organs are flipped to the opposite side. So your heart’s on the right, your liver’s on the left, etc.) I was helping people dissect yesterday when I saw one of the team’s bodies where the apex of the heart was pointing toward the *right*. First I thought, “Did they detach the heart and flip it around? But it was firmly stuck in there. I started to get excited, thinking it had to be situs inversus, so I felt down toward the *left* side of the diaphragm, and felt the liver. There it was!
I called the professor over to confirm it, and he agreed–it was the first case he had ever seen. Very exciting. The whole lab swarmed to check it out, and I called the other TAs over to see it. Absolutely fascinating. I can’t wait to see the abdomen.
Situs inversus is a 1/10,000 occurrence, and some believe it occurs due to a mutant cilia protein that causes the cilia to beat in the opposite direction. This then pushes developmental proteins in the fetus to the opposite side, and voila, mirror image.
Unfortunately for the dissecting students, they’re going to be *totally* confused. I told them to make sure they primarily study different bodies… otherwise, they’ll be totally lost.
I'd be pretty excited, too
"Did they detach the heart and flip it around?". Yeah, you never can trust those med students.
Sweet. The closest I ever came to something like that was a cat where the two common iliac veins didn’t converge to form the inf. vena cava until just north of the kidneys. That was one sorely confused student.
Awesome find!
There’s actually a good deal of research on Kartagener’s syndrome — a triad of situs inversus, immotile sperm, and decreased mucus clearance from the bronci.
All symptoms come from a defect in cilia, that causes them to stop beating altogether (not beat in the opposite direction).
It’s believed that the flicking of cilia promotes proper organ arrangement in the embryo. Turn off the cilia, and organs are left to their own devices (and maybe gravity) — if I recall, it’s probably 50/50 whether the liver’s on the right or left, without cilia.
So (after a bit of thought) you might be able to nail the diagnosis if you check for bronchiectasis in your cadaver.
I don’t know of other signs of cilia dyskinesia that may manifest on the gross anatomy level. But keep us posted, what with the title of your blog and all.