1 Department of Anatomy, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand. Electronic address: ming.zhang@anatomy.ac.nz.
2 Department of Anatomy, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand. Electronic address: kawan518@student.otago.ac.nz.
3 Department of Colorectal Surgery, Concord Hospital and Discipline of Surgery, Sydney Medical School, The University of Sydney, NSW, Australia. Electronic address: pierre.chapuis@sydney.edu.au.
4 Department of Colorectal Surgery, Liverpool Hospital and School of Medicine, University of Western Sydney, NSW, Australia. Electronic address: L.Bokey@uws.edu.au.