Reptile & Amphibian Forums

As some of you may recall, I have a male lineatus who had tail damage from a bite when I received him. The tail tip had only the black telltale "V" of a bite upon arrival, within a day the thin tissue layer under the skin filled with fluid and went thru the normal necrosis process whereas it dried up, and fell off, healing quite nicely. The missing part comprises approximately 1/2 inch of tail, has shown no evidence of regeneration whatsoever after several months.

I got a new female in recently who at some point lost the very tip of her tail, perhaps 1cm, and it has been regenerating (small pointy "tip" growing from the middle of the tail).

So this makes me wonder, what is the determining factor for stimulating tail regeneration? The only thing I can think of is stressful loss... Does anyone know what actually triggers it? It just seems odd that a complete drop regenerates, a loss of the tip as well, but a partial loss has not?

-Leah
-----
www.wildeyereptiles.com

Chameleons, geckos & invertebrates

was actual bone broken in the first animal? I might have a poor idea of how this regeneration works, but a professor here at vet school gave this explaination as a side note when doing histology of bone, but keep in mind OSU has nothing along the lines of reptile medicine.

He said when a tail "falls off" in a lizard, its breaks at the joint between two bones. This somehow causes the cartilage and joint material to prolifeate and make a new tail, with skin and such following the new cartilage growth. The trick is that the new tail is always cartilage and not replaced with bone. I wonder if the joint capsule isnt damaged, if there is still a proliferative response. Maybe your animals tail's broke in a different manner? I'm just guessing from hearsay. to be honest i have no clue if this process is active in your animals, or if his description was even accurate.

Leah,

My female lineatus lost her entire tail the day I picked her up and hasn't started any kind of regeneration at all. Its been nearly two months and not even a speck of growth. I figure she probably broke the tail at such a spot where it negated the regeneration possibility. I'll think about it and talk to one of my bosses and see if she has any input.

cheers
Jason

There are several available journal articles on this subject, some specifically concentrating on the origin of newly developed tissues. Many suggest that regeneration can only occur from differentiated cells directly anterior to the fracture plane.

I have never seen Uroplatus spp. lose its tail voluntarily and reactively (key words) at any plane other than in the most anterior portion of the tail. I have however, heard of them injuring a portion of their tail and soon after dropping the entire thing.

I think your case, because injury was sustained to the tip of the tail (the gecko was lucky not to drop it entirely) it was not injured at a fracture plane. Therefore, it will not regenerate the lost portion. It is my speculation that this is "normal" tissue not capable of genesis. For example, much like if your dog lost a limb it will never grow back.

PS... And dart frogs can't produce their own toxins dammit...
-----
Ben

And the female with just the very tip regenerating?
-----
Visit us at www.wildeyereptiles.com

quite puzzling indeed... i would not think it possible...
-----
Ben

haha, nice ending to your post, it made me laugh.

the "joint" that he talks about is actually a well-defined breakage plane in a lot of lizards, but as we all know not all lizards are prone to autotomize. due to the morphology of uroplatid tails, it seems like they wouldnt have these breakage plains distally on the tails (although this is some speculation from observation, not any research). a lot of lizards have very muscular and/or fatty tails, but thats a bit different from most leaftails. the flattening of the tail, if i recall correctly, is mostly dermal, not muscular. so essentially it seems as though there would be one to a few main breakage planes proximal to the origin of the tail, where most startled/mishandled/whatever leaftails will break their tails off. but if you go further out where the tail begins to flatter, if you broke off a piece there, the breakage plane would need to extend all the way out into where the tissue is mostly dermal, and essentially you'd have a broken tail that would still be attached by skin at least until ripped, cut, or rotted off. that would be a bit less adaptive because the writhing tail LEFT BEHIND is what distracts the predator.

kinda went off on a tangent here, cant really remember if im answering any of the questions asked, but hey its a lil tidbit of info. i could dive into my herpetology book and see if i can find anything about the mechanics of autotomy & regeneration.

Did the trauma occur laterally? Since the female is regenerating after the loss of the tip, perhaps the process is initiated by trauma to the middle region of the tail?

I have no idea, she came to me with regenesis already partially complete.
-----
Visit us at www.wildeyereptiles.com