allantoid membrane n.
a vascular, extraembryonic membrane of birds, reptiles, and certain mammals that develops as a sac or diverticulum from the ventral wall of the hindgut. Historical Examples An embryonic appendage, the allantois, used in reptiles and birds for respiration, has here been turned to another purpose. The Whence and the Whither of Man John Mason Tyler […]
- Allantoidoangiopagous twins
allantoidoangiopagous twins allantoidoangiopagous twins al·lan·toi·do·an·gi·op·a·gous twins (āl’ən-toi’dō-ān’jē-ŏp’ə-gəs) pl.n. Unequal monozygotic twins with fusion of their allantoic vessels within the placenta. Also called omphaloangiopagous twins.
a white powder, C 4 H 6 N 4 O 3 , produced by oxidation of uric acid and the major excretory product of purine degradation in many vertebrates: used medicinally to heal skin ulcers and in lotions, lipsticks, etc., for its soothing effect. noun a substance derived from the secretions of snails and contained […]
allantoinuria allantoinuria al·lan·to·i·nu·ri·a (ə-lān’tō-ə-nur’ē-ə, -nyur’-) n. The excretion of allantoin in the urine.