First of all, what is Eroguro? Ero-guro, also spelled eroguro, is a Japanese artistic movement that was born as a protest to the taboo subjects of that country. This lexeme can be divided into ero, which refers to eroticism; and guro, which is oriented to the grotesque; so in its artistic manifestations you can find the use of blood, gore, and different types of paraphilias or fetishes (such as necrophilia and, for reasons that only the Japanese will understand, sex with giant insects, too much sex with giant insects in fact).

In the early 2000s on 4chan, a site for people even sicker and even more dangerous than those who use this site, a thread about necrophilia was posted, very simple in content but very remarkable for being perhaps one of the first records of an attempt at "trolling" using Gore.

Dissected-chan was originally posted on gurochan but the images were quickly removed and the user was banned; because, well, they were (supposedly) real images and not Japanese cartoons. The images were downloaded by one guy, and quickly posted on /b/ (a sub-board) of 4chan.
Posted in 2007, it was created right after 5 minutes was posted on Gurochan first, possibly all done by the same person.

The worst part is that whoever the madman was who did this was clearly just as sick as a certain person named "Johnnie", since he/she went to the trouble of writing a text that made clear his/her fantasies which were so disturbing that even people who enjoy this same kind of fantasies were disgusted by its publication.
No one knows where these images are really from but it is theorized that the images are 100% real and that they come from the autopsy of the corpse of a girl of the same name that you will read below who died in a traffic accident.

And here is the Copypasta extracted from the original post:

"Ever wanted to see how eroguro look alike in the real? This poor girl died just yesterday. Her name was Alex she was 19 and she died a virgin. So I played a little with little dead body of her. She did not complain at all :) First of all I sawed her skull and took out her brain and then cut her open from chest to pussy. Then I put my fingers into her pussy and found that she a virgin! Wow! That's was cool! I played with her pussy with my fingers. And than, I took her cherry with the spray can. No blood at all since she was dead. Than I take her eyeballs out and look for some funny stuff I can do with them. Girl, with her own eye in the mouth! Have you ever seen anything like that? Or pussy with the eye. Finally I get so excited that fucked her. In was kinda strange feeling since she was cold all right and her blood and the stuff was all over but I cum just in few minutes. It was best cum ever! Sooo cool! I was all laughing inside when I gave her body to her parents. She was all cleaned and with make up just like alive. They were just stunned by her death such a tragedy. And I was all laughing inside since I know that this little baby will to the grave with pussy full of my sperm. Ha-Ha-Ha-Ha-Ha!!!!"