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Horsegen, Nerd, et all...

Can someone tell me what defines "dorsal" genetically? I mean if some random gene (have nothing particular in mind here) were to decide it wanted white on, and only on, the "dorsal" of the horse, where would the white be? I'd be interested to know both the approximate width and length of this "line". Same question for "ventral" out of curiosity. Thanks!!

horsegen Sun, 04/19/2009 - 14:32

There's no "lines" drawn on the horse (or any animal), per se. Dorsal just means the top (or back) of the animal, and ventral means the bottom (or belly) of the animal. A gene that acts to put white dorsally would place the white from the back downward, and a gene that acts to put white ventrally would place the white from the belly upward. The white could only be a small amount, or it could be a large amount, extending far down/up the sides of the animal. Genetically, we use dorsal or ventral to determine the starting point of the gene action, as that has implications for development.

Does that help? I hope it's not too confusing...

accphotography Sun, 04/19/2009 - 14:36

Nope. It makes sense to me.

If the white went from the dorsal (spine in this case I assume) downward, where would the start and stop of that line be (poll to dock for example... or?)?

Monsterpony Sun, 04/19/2009 - 16:38

If you look at it embryologically, dorsal is along the top of the spine. Basically, embryos start out as sheets of cells that folds in on itself and connects along the spine and forms that spinal canal defining the dorsal aspect. Ventral is where the cells meet opposite of that after in-folding to form the body cavity.

In this image- B and C show the formation of the dorsal aspect, C and D show the ventral.

http://pubs.niaaa.nih.gov/publications/…" onclick="window.open(this.href);return false;

Monsterpony Sun, 04/19/2009 - 19:58

Not all of the face, just the part above the brain for the most part. Like how maximum expressed splash tends to leave the ears and along the back which would be the dorsal most aspects, but the tail tip and muzzle/face are white.

accphotography Thu, 04/30/2009 - 17:06

Ok. Next question. So where does the dorsal stripe on a dun horse normally stop and start lengthwise? Does it go into the mane and tail or is it just the back, etc?

horsegen Thu, 04/30/2009 - 18:12

The dorsal on a true dun does extend into the tail, although the length that it does is variable. Usually at least 6 inches, but I've seen the dorsal be prominent in the for one or two feet. That's a function of the tail bone underneath, so it seems that the dorsal patterning sometimes extends through the entire spine (to the end of the tail bone) and sometimes not quite that far. But we have no real way of measuring that. The mane is harder--certainly the dorsal usually appears to "disappear" into the mane at the withers, but the length that it extends into it is hard to see.

PamelaTX Thu, 04/30/2009 - 20:43

[color=#8000BF][b]Oooooooooooooo he's nice!!! I think I'm in LOVE!! lol
Does he have a website?
He's really NEAT!![/b][/color]

horsegen Thu, 04/30/2009 - 21:05

Duns often have a "face mask." This looks like a restricted face mask to me...maybe his has been restricted due to his homozygosity? Just a wild guess! I don't usually see too many face masks in QH, but it's pretty common in other breeds.

PamelaTX Thu, 04/30/2009 - 21:17

[quote="horsegen"]Duns often have a "face mask." This looks like a restricted face mask to me...maybe his has been restricted due to his homozygosity? Just a wild guess! I don't usually see too many face masks in QH, but it's pretty common in other breeds.[/quote]

[color=#8000BF][b]Isn't the masking the darker hairs on the face??
Like on Jackie[/b][/color]
[img]http://i209.photobucket.com/albums/bb25…]

PamelaTX Thu, 04/30/2009 - 23:59

[quote="accphotography"]I see the mask, I'm talking about the line coming down from his forelock. Darn sure looks like a dorsal stripe to me.

http://www.dunitslidinquarterhorses.com…" onclick="window.open(this.href);return false;[/quote]

[color=#8000BF][b]Oh THANK YOU!!! LOVE his breeding & he's just GORGREOUS!!!!!!!![/b][/color]