1. relating to or resembling the allantois, a membrane that develops in embryos of mammals, birds, and reptiles
Usage: biology; embryology

1. the allantois membrane itself, or an organism or structure resembling it
Usage: biology; embryology

Examples

• The allantoid membrane plays a crucial role in nutrient exchange during fetal development.
• In birds, the allantoid structure helps with gas exchange and waste storage.
• Embryologists study allantoid tissues to understand how mammals develop in the womb.
• The allantoid sac expands as the embryo grows larger.
• Reptile embryos rely on the allantoid for respiration and waste management.