1. of, relating to, or involving the allantois (a membrane that develops in embryos of mammals, birds, and reptiles)
Usage: technical; biology

Examples

• The allantoic membrane plays a crucial role in fetal development.
• Allantoic fluid surrounds the developing embryo in many vertebrates.
• The allantoic sac helps facilitate gas exchange during embryonic growth.
• Researchers studied the allantoic tissue to understand placental formation.
• The allantoic vessels contribute to the formation of the umbilical cord.