Most Dense, Liquid Repelling Organ?

[goatsrunfaster]

Hello Everyone,

 

Im working on a project where Im trying to extract DNA from recently fixed fish specimens stored in Formalin. The problem is that formalin degrades DNA. I was wondering if anyone here might be able to interject with what might be the least penetrable (most dense) organ in the human body (which would likely be the same for fish), one that would potentially take the longest to be penetrated by the formalin. Maybe there is an organ thats not so dense, but would some how keep the formalin from penetrating the interior? Basically something that is in-penetrable by liquid on the outside???... Any help or even suggestions would be greatly appreciated.

 

Best,

Spencer

 

 

[CharonY]

What do you need the DNA for? There are a large number of protocols dealing with fixed tissue. Even with tricky specimen (older, fixed tissue slices) DNA of decent quality (especially if used for simple things like PCR) can be obtained.

That being said, penetration rate depends largely on the fixation technique and the size (volume) of the specimen. If a small fish is submerged fully, it will take a few days for it to penetrate all organs. Often, formalin is directly injected into the gut, to prevent rotting in the time frame. So if the sample is fresh, digging into deep tissues could give relatively clean samples. The type of tissue has little effect on the penetration rate.