Date: Motzaei Shabbos, first night of Selichos, 5596
From: Rabbi Moshe Sofer
To: Rabbi Shmuel Duks
The Chasam Sofer rules that selling one's body for post-mortem dissection is forbidden on multiple grounds: a Jewish corpse is prohibited in benefit by Torah law, general medical study does not constitute pikuach nefesh, and consenting to one's own desecration shows contempt for the divine image. He concedes that dissection would likely be permitted if a specific living patient with the same illness were present and could be directly aided by the findings.
Source: Shu"t Chasam Sofer YD §336