noun
- Plural of allantoid; membranous sacs that develop in the embryos of mammals, birds, and reptiles, serving respiratory and excretory functions.
Usage: technical; biology
Examples
- The allantoids of bird embryos help facilitate gas exchange during incubation.
- In mammalian development, allantoids contribute to the formation of the umbilical cord.
- Reptile embryos rely on allantoids for waste storage and respiration.
- The study examined how allantoids function across different vertebrate species.
- During early development, allantoids extend from the yolk sac into the extraembryonic coelom.