“Super-Microsurgical Anastomosis training using the chick embryos within the “Egg-in-Cube” system.”

Although the super-microsurgery technique is an essential skill for lymphatic surgery or perforator flap surgery, an ideal training model is yet to be found. Living animal models, such as rodents, are considered to be ideal microsurgical training models. However, the use of living animal models is costly and there are bioethical considerations. Hence, we aimed to develop a novel, cost-effective, highly reproducible, and easy-to-handle super-microsurgical anastomosis training system using the chicken embryo within the "Egg-in-Cube." The chick embryos were fertilized in the artificial cubic eggshell, which was fabricated by integrating a polycarbonate frame structure and five polydimethylsiloxane (PDMS) membranes. Seven days later, the trainees underwent super-microsurgical training using the vitelline artery of the chick embryo. The trainees were able to perform super-microsurgical training using all eleven surviving chicken embryos. The average diameter of the vitelline artery was 0.43 mm. Patency and pulsation were observed after the anastomosis in four of the eleven cases. The super-microsurgical training system using the chicken embryo within the "Egg-in-cube" has several advantages. First, this system is ethically acceptable. Second, this system is less costly and easier to manage than other animal models. Third, this model is suitable as a super-microsurgical training model such as lymphovenular anastomosis (LVA) because the diameter of the vitelline artery was similar to that of the lymphatic vessels in lymphedema patients. Moreover, the trainee can confirm patency and leakage after the anastomosis because this model has a circulation system. The trainee can practice the super-microsurgical technique efficiently with simultaneous feedback on anastomosis results.