Origin and function of the yolk sac in primate embryogenesis | Nature Communications
Pilot study establishing a nomogram of yolk sac growth during the first trimester of pregnancy - Detti - 2020 - Journal of Obstetrics and Gynaecology Research - Wiley Online Library
Yolk sac hi-res stock photography and images - Alamy
Early Pregnancy and the Yolk Sac - Somerset Early Scans
Figure, Normal gestational sac. Image courtesy S Bhimji MD] - StatPearls - NCBI Bookshelf