Minimally invasive (laparoscopic) surgery became a major part of general surgery with the introduction of laparoscopic cholecystectomy in the late 1980s. This was the culmination of the development of instruments and techniques by many physicians; Kelling developing pneumoperitoneum, Zollikofer using carbon dioxide, Kalk designing a lens system and the dual-trochar technique, Veress using the Veress needle to create pneumoperitoneum, Hasson developing the Hasson trochar, Semm carrying out the first laparoscopic appendectomy, and Muhe and Perrisat carrying out and popularizing laparoscopic cholecystectomy. At the present time, minimal invasive surgery has become the most important part of general surgery.