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

 

Advertisements
Standard
Cases

Extra toes!

Are cats evolving opposable thumbs??? (More pictures here)

Cat with opposable thumbs!?

Cat with opposable thumbs!?

Probably not.  Polydactyly is a condition where extra fingers and/or toes develop in animals.  Sometimes they are fully formed, sometimes they just form a small under-developed finger-like lump.  Usually there is a genetic defect that causes the extra digits, but it has been associated with the mother taking some types of medications at particular points during pregnancy.

Extra fingers and toes with near-normal anatomy in a human.

Extra fingers and toes with near-normal anatomy in a human.

220px-Polydactyly_01_Lfoot_APPolydactyly can occur in many species, and is sometimes associated with other abnormalities such as limb deformities and heart problems.  It may cause no problem at all, and can assist with mental arithmetic.

Polydactyly in a chicken.

Polydactyly in a chicken.

 

Standard
Cases

I’m sticking with you.

It’s almost the Easter weekend, which means the UK lambing season is well underway! For the past couple of months, exhausted farmers tend their flocks and we all get to see cute lambs springing around in the fields. However most of us know it’s not all nice, with shows like Lambing Live  illustrating the unique problems of this time of year.

It unfortunately comes with the territory that with vast numbers of animals being born all at once, there are inevitably mortalities. With such huge numbers of births, there is also a good chance that at some point you’ll encounter some very strange developmental abnormalities.

One head good, two necks baaa-d

One head good, two necks baaa-d

 

One such abnormality is conjoined lambs, where two foetuses develop stuck together. These lambs had one body, two necks and a shared head. They also had partially separate organ systems.

 

Unusually for conjoined lambs, the face was almost normal  (more often there are two distorted faces)

Unusually for conjoined lambs, the face was almost normal (more often there are two distorted faces)

These twins are similar to the skeletal specimen, sharing a head with an almost normal face.

Probably how the lambs would have looked – these taxidermied lambs also share a head with an almost normal face

 

Two spinal cords are seen entering the skull and there is a cleft palate.

From underneath, you can see there is a cleft palate.

These lambs also had a cleft palate in their shared head – a hole in the roof of the mouth, where the bony plate between the nose and mouth hasn’t formed properly. If the lambs had lived, it is likely the milk they drank would have passed into the nose and been inhaled, causing pneumonia.

Side view

Side view

 

Twins conjoined at the chest and head.

Twins conjoined at the chest and head.

Conjoined twinning is a relatively common developmental problem in animals, and similar to the parasitic twin phenomenon. It is more often seen in domesticated animals since they have more care and better chances of survival than their wild counterparts.

Happy Easter!

Happy Easter!

Standard
What's this?

What’s this? #3 Assume the cow is a sphere…

What was up with that beef ball? Was it those pesky physicists again, trying to validate their theoretical model?

It’s actually a globosus amorphous (not “amorphous blobosus”, as I used to so confidently tell people…) — where a fertilised egg doesn’t develop properly in the womb. Instead, it tends to form a ball of fat wrapped up in skin, and feeds parasitically on the umbilical cord of its twin (you might also know someone like this).

Umbilicus (I bet it would have been an outie bellybutton)

Umbilicus (I bet it would have been an outie bellybutton)

Also known as an ‘acardiac acephalic twin’ (acardiac = without heart, acephalic = without brain) or ‘acardiac amorphous twin’, these form as a result of abnormal development of one of a pair of twins (or septuplets!). They most commonly occur in cattle, but also occur in several other species such as goats, sheep and horses.

The normal twin is usually called the ‘pump twin’ because it provides the oxygenated blood to the abnormal twin which has no heart of its own.  Blood comes from the mother, via the placenta to the normal twin.  It then leaves the normal twin and, instead of going back to the mother, travels through the acardiac twin.  BUT the blood actually flows the wrong way around the acardiac twin as a result of this hijacked perfusion.  The blood flows to the intestinal arteries first, and because the blood has already flowed through the mother and normal twin first, it is super low in oxygen.  This is why, if anything develops at all, it is usually only the hind limbs and some organs — the parts that got any oxygen.

Our little guy only managed an eye socket and a piece of cartilage, which is why it was so shapeless and easily mistaken for a guinea pig or plush pathogen.

Sock it to me!

Sock it to me!

Piece of cartilage

Piece of cartilage

Standard
Cases

Monster tumour!

When an animal develops from the fusion of an egg and sperm cell, the first cell will divide and divide until a large ball of cells is formed.  These cells will go on to produce the entire animal, the placenta and membranes that surround it during development.  The organs and tissues formed from these cells are all very different from the original cells – we say that these cells have differentiated.  The cells can go down three possible routes:  The innermost layer of cells will form all of the guts, lungs and liver.  The middle layer of cells will form the skeleton, muscles, heart, blood and kidneys.  The outermost layer will form the skin and nervous system.  Eventually the developing animal will have a vast array of different cell types e.g. nerve cells, muscle cells, liver cells etc.

The cells undergoing their initial divisions.

The cells undergoing their initial divisions.

All of these cells have the potential to go wrong and form tumours e.g. brain tumours, muscle tumours and liver tumours.  Generally, these tumours will be made up of one cell type, e.g. the haemangiosarcoma we saw in a previous post was a tumour originating from the blood vessels, so the tumour itself was made up of a mish-mash of badly formed blood vessels.

In the ovary and testicle there are lots of cells which form the egg and sperm cells (germ cells) of the animal.  The job of these germ cells is to make complete new animals, so these cells have the potential to become ANY cell in the body during development of the foetus.  If this development goes wrong, and a tumour forms, the cells which make up the tumour could become any cells imaginable!

A teratoma from the chest.

A teratoma from the chest.  There’s a hair within the large cystic space.

A teratoma (‘terato’ comes from the greek for monster, and ‘-oma’ comes from the greek for tumour) is a tumour which consists of cells from all three layers of cells found during development.  We can find whole teeth, skin, glands, cartilage, bone, hair, muscle, fat, spleen, nerves and many more tissues inside these monstrous tumours.  These tumours originate from cells which have the potential to form other types of cells (stem cells), and stem cells are found all over the body, but they are in their largest numbers in the testicles and ovaries.  It goes without saying, that these are the most common sites for teratomas.

They cause a problem because they can grow quite large and interfere with the normal function of the organ in which they are growing.  Generally they are benign (teratoma), as they contain well-formed cells which don’t behave very aggressively.  However, sometimes some of the cell types within the tumour might not form fully or may be altered so that they become invasive and the tumour can be malignant (teratocarcinoma).

The eye and tumour are cut into a very thin section and put on a microscope slide.  The blue arrow is the eye, the black arrow is the tumour.

The eye and tumour are cut into a very thin section and put on a microscope slide. The blue arrow is the eye, the black arrow is the tumour.

In this case, a tumour was found behind the eye of a bird.  It was composed of a very bizarre mixture of lots of different tissues:

The black arrow points to a piece of cartilage with overlying tracheal tissue (respiratory epithelium - blue arrow).  The red arrow points to intestinal tissue (villi)!

The black arrow points to a piece of wind-pipe cartilage (respiratory epithelium – blue arrow). The red arrow points to some intestine!

Lobules of pancreas within this tumour.

Lobules of pancreas within this tumour.

There's even a fragment of muscle...

There’s a fragment of muscle…

...a large piece of cartilage.

…a large piece of joint cartilage.

There's even brain tissue in here!

There’s even brain tissue in here!

bone and marrow

The black arrow shows bone and the yellow arrow points out bone marrow. It’s almost like a whole new animal is growing within this tumour.

Standard