Pigeon varieties: a high-white coat marking

Pittman & Davis

Pigeon varieties: a high-white coat marking

Image by ressaure
High-white marking in animals is when pigmented areas are few and distributed erratically or even practically absent due to the lack of pigment cells in proper places, making the animal "pied" or even completely white. It’s opposed to the true albinism when the pigment cells are there, but the whole mechanism that produces pigments is "broken" genetically.

In many animals, including dogs, horses, rats, and humans, high-white marking is sometimes linked with serious health issues.

The thing is, nerve cells and pigment cells are embryologically related – they form from the same type of stem cells.

These cells first appear in the part of the embryo called the neural ridge located on the embryo’s back, and gradually migrate towards extremities to their future "job sites", turning into nerve cells and pigment cells.

When the migration process of pigment cells is disturbed for one reason or another, the cells don’t reach their destination, and their target areas remain white – those are usually the areas most distant from the neural ridge, i.e. paws, tail tip, forehead, etc.

Amazingly yet logically, domestication is linked to the appearance of white markings.The neurological changes necessary to make animals tame, i.e. which reduce their self-defence instincts and fight-or-flight responses, are so fundamental that they disrupt the whole system on a very, very basic level, when an organism is still a cluster of stem cells 🙂

This process often happens in a "controlled" manner, as it does, for example, in many pets, resulting in standard white markings (cats with white socks, horses with white stars on their foreheads, the white patches on a collie dog, etc). But sometimes the migration process goes wrong, and not only the pigment cells fail to migrate, but the future nerve cells, too.

That’s exactly the reason why white cats are often deaf – nerve cells supposed to innervate their inner ear have failed to migrate; for the same reason dalmatian dogs with blue eyes and white ears are disqualified, because they are often deaf or produce deaf offspring; high-white marking in horses is connected with the lack of colon innervation – the so called "lethal foal syndrome". Humans are also prone to this genetic error – it’s called the Waardenburg-Schah syndrome, causing a disease called Hirschprung’s disease. Individuals with this genetic disorder among other things often have odd eyes and a patch of gray hair or a streak of pink skin on their foreheads.

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4 comments on “Pigeon varieties: a high-white coat marking

  1. I agree with all of the above!

  2. Beautiful shot and some interesting info.

  3. sandeep_80(very busy)

    Wonderful shot !!

  4. Dan Belton ( No Computer )

    I don’t think I’ve ever read a more interesting and informative description; reminds me of a biomedical neuroscience module I did while studying zoology at university ( the nervous system is just endlessly fascinating ! ). A lot of that I didn’t know though and I’d always wondered why why white cats are often deaf, oh, a really detailed and well exposed image too !

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