In ovo is Latin for in the egg. In medical usage it refers to the growth of live virus in chicken egg embryos for vaccine development for human use, as well as an effective method for vaccination of poultry against various Avian influenza and coronaviruses. During the incubation period, the virus replicates in the cells that make up the chorioallantoic membrane.[2][3]
^Ricks CA, Avakian A, Bryan T, Gildersleeve R, Haddad E, Ilich R, et al. (1999). "In ovo vaccination technology". Advances in Veterinary Medicine. 41: 495–515. doi:10.1016/S0065-3519(99)80037-8. PMID9890038.