#allantoid
- Allantoid — Pertaining to the allantois, or having the shape of a sausage or an elongated sac; allantoidian. In structural medical and biological terminology, the term describes the morphological configuration of certain embryonic appendages, fetal membranes, or elongated cavitary structures that appear during the early development phases of amniote vertebrates.
- Allantois — A sac-like, highly vascular embryonic membrane characteristic of reptiles, birds, and mammals, developing as a diverticulum of the fetal hindgut; a structural organ with vital functions in embryonic respiration, excretion, and nutrition, actively participating, in placental mammals, in the formation of the umbilical cord and placenta through its dense network of blood vessels.