How does WPF store the language dictionaries?

Question

According to https://msdn.microsoft.com/en-us/library/system.windows.controls.spellcheck(v=vs.110).aspx

There are 4 languages supported. How does it store the dictionaries? Is it a (signed) resource file? An access database?

Mostly, I need to get access to the list of the words in the dictionary, so programmatic access to that word list would be great, but I'm also curious about the implementation.

I have traced it down to the SpellerInterop, but then if I understand my COM (And I'm not trying to say I do, it calls to a DLL with a guid (d385fdad-d394-4812-9cec-c6575c0b2b38). I don't know how to dig into that guid. Can anyone help?