Tortie brindle and calico patches
Have you ever noticed that the colors on tortoiseshells with lots of white are separated much more clearly than on tortoiseshells with little or no white?
The first cat has very small, intertwined black and red patches, while the second one has well defined, big patches. What could cause this phenomenon?
To answer this, first let’s talk about the melanocytes.
Melanocytes are the cells in the skin that produce pigments. As you can see on this illustration, one melanocyte affects the color of several skin cells.
In tortoiseshells, each cell has an X chromosome with the black and one with the red allele. Because of biological reasons i won’t get into, they all “turn off” one of their X chromosomes, choosing between them randomly. (This is called X-inactivation.) The melanocytes produce pigments according to their active X chromosome’s orange allele. The differently colored patches on the tortoiseshell pelt is the area a single melanocyte, or more precisely, its clones reach.
But why is it different based on the level of the white spotting?
During the development of the embryo, at a specific point the ws (white spotting) allele stops the creation of new melanocytes on the surface areas. This means if the embryo grows after this point, the melanocyte coverage breaks up and the uncovered, new body parts become white.
In colored cats, new melanocytes with their randomly inactivated X-chromosomes are created for much longer, so they’ll be present in much bigger numbers, therefore every cell will have much less space to further divide. This is why no-white or little white tortoiseshells have small patches.
If the melanocyte creation stops earlier, the single melanocytes have lots of space to divide, and they’ll form big clone colonies. You can see them on calicos: at a very early point of the cat’s life, every red and black patch was one single melanocyte.
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challenge was draw cinderpelt, ashfur, bluestar and crowfeather on the same canvas to test your design flexibility!
not my og idea but if anyone wants to use this as a post to reblog to show their own versions that's fine!
also, if you want to challenge yourself further, (just pick and choose)
- sootfur
- rainwhisker
- perchpaw
- ravenwing
- ravenpaw
- frostpaw
- bristlefrost
- dovewing
- cinderheart
- lilyheart
- tadpole
- mistystar
- stonefur
- stormfur
- willowshine
- needletail
- tall shadow
- grey wing
- hawkwing
- stormcloud
- nightheart
- twigbranch
- breezepelt
- nightcloud
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