Cases

Cyclops!

The title might give you one eye-dea about today’s topic – yup, we’re talking about cyclopia! Our fun-loving, larger-than-life, mono-ophthalmic monster buddies were first written about by the ancient Greeks, and later adopted by the Romans.

Luckily he has really bad depth perception

Lucky for those guys, he has really bad depth perception

The origins of the cyclops myth has been the subject of much discussion. Some suggest that the Greeks might have stumbled across the fossilised skulls of prehistoric dwarf elephants, and these creatures being extinct and unfamiliar to them, mistaken the schnozz-socket for a single giant eye.

Nasal cavity vs. actual eye hole

Nasal cavity vs. actual eye hole of an elephant skull

Others think that the Greeks had actually seen cyclopes in the flesh. A couple of rare developmental problems can result only one eye: in true cyclopia, only one eye is formed, whereas in synophtalmia, there may be two eyes which fuse.

Cyclopia

Itty bitty cyclops kitty

The Sonic Hedgehog and Pax6 genes are involved in properly dividing the embryonic brain (and extensions from it, such as the eyes) into two separate hemispheres.  There are several things that interfere with this process and so cause cyclopia, including certain drugs, viruses, genetic defects, and radiation. Alkaloid toxins in plants are also a culprit. In fact, ancient Greeks used some of these plants medicinally, and perhaps as a result, did see ‘real’ cyclopes…

Elephants and cyclopes also have another thing in common. Interestingly (or maybe morbidly), some cyclopes develop a tube-like structure instead of a nose, which is called a proboscis because it resembles a tiny trunk.

A cyclopic lamb with a proboscis, or trunk, above its eye

A cyclopic lamb with a proboscis, or trunk, above its eye

 

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What's this?

What’s this? #9 Epitheliocystis

This was a tricky one! Well done to paleomanuel for a superb answer, recognising that this was a magnified picture of fish’s gills.

Normally when we take cross-sections through the gills, we should see thousands of finger-like projections called lamellae. Like the thousands of alveoli in our lungs, the lamellae massively increase the surface area available for gas exchange when water is flowing over them.

The gills form thousands of folds to increase surface area for gas exchange in the water. These gills are relatively normal apart from one affected cell

The gills form thousands of folds to increase surface area for gas exchange in the water. These gills are relatively normal apart from one affected cell.

In this disease, billions of blue-purple staining bacteria (Chlamydia-like species) are replicating within the epithelial cells which line the gills and skin, causing them to balloon out and form cysts. Because of this, the disease caused by these bacteria in the gills is called Epitheliocystis.

The big blue-purple blobs are big colonies of bacteria within the cells lining the gills.

The big blue-purple blobs are big colonies of bacteria within the cells lining the gills.

It is quite a rare cause of disease in wild fish, but occurs more frequently in fish farms because the high stocking densities mean that the bacteria can spread more easily.  Their thickened and damaged gills means that affected fish may die because they are unable to extract oxygen efficiently from the water.  Inflammation of the gills is called branchitis (not to be confused with bronchitis! = the inflammation of the airways in the lungs of mammals, birds, and most reptiles).

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