In-ovo imaging using ostrich eggs—Evaluation of physiological embryonal development on computed tomography

In-ovo imaging using ostrich eggs has been described as a potential alternative to common animal testing. This approach is independent from small animal imaging devices as ostrich eggs provide good image quality on computed tomography (CT), MRI or PET scanners used in clinical routine examinations. However, questions regarding physiological development and systematic evaluation of image quality are open. This study aims at describing physiological development of ostrich embryos on serial CT scans. One hundred eggs (63 fertilized and 37 non-fertilized) were artificially incubated for 37 days. On developmental days (DD) 0, 10, 19, 22, 25, 28, 31, 34 and 37, CT scans were performed using a Siemens Biograph mCT40. Density of yolk, albumen and shell as well as volumes of air cell, egg content and egg shell were determined. In fertilized eggs, the size of different osseous structures was investigated. Detection of embryonal development was technically successful in 100%. Distinguishing of fertilized and non-fertilized eggs is achieved as early as DD 22. After that, continuous development is depicted and osseous structures become visible on DD 25. Ostrich eggs might open the door for preclinical imaging studies if small animal imaging devices are not available. This study contributes to the implementation of ostrich eggs as an alternative to common animal testing.