Ibn al-Nafis
There is some debate about whether or not Ibn al-Nafis participated in dissection to come to his conclusions about pulmonary circulation. Although he states in his writings that he was prevented from practicing dissection because of his beliefs, other scholars have noted that Ibn al-Nafis must have either practiced dissection or seen a human heart in order to come to his conclusions. According to one view, his knowledge about the human heart could have been derived from surgical operations rather than dissection. Other comments found in Ibn al-Nafis' writings such as dismissing earlier observations with a reference to dissection as proof, however, support the view that he practiced dissection in order to come to his conclusions about the human heart and pulmonary circulation. Ibn al-Nafis' comments to the contrary and the alternate explanations, however, keep his possible practice of dissection in question.