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DictionarySeeair sacalveolar sac
al·ve·o·lar sac1. terminal dilation of the alveolar ducts, which give rise to alveoli in the lung; a small air chamber in the pulmonary tissue from which the pulmonary alveoli project like bays and into which an alveolar duct opens; Synonym(s): sacculus alveolaris [TA]2. in birds, air-containing extensions of bronchi that connect with bone cavities. Synonym(s): air sacal·ve·o·lar sac (al-vē'ŏ-lăr sak) Terminal dilation of the alveolar ducts that give rise to alveoli in the lung; a small air chamber in the pulmonary tissue from which the pulmonary alveoli project like bays and into which an alveolar duct opens. Synonym(s): sacculus alveolaris [TA] . sacS00-828880 (sak) [L. saccus, sack, bag] A baglike part of an organ, a cavity or pouch, sometimes containing fluid. Synonym: saccus See: cystair sacIn a mammalian lung, an informal term for “pulmonary alveolus.” See: alveolus.allantoic sacThe expanded end of the allantois, well developed in birds and reptiles.alveolar sacPulmonary alveolus.amniotic sacThe inner fetal membrane that encloses the developing fetus and produces amniotic fluid. See: chorionchorionic sacThe outer fetal membrane that encloses the developing embryo.conjunctival sacThe cavity, lined with conjunctiva, that lies between the eyelids and the anterior surface of the eye.dental sacThe mesenchymal tissue surrounding a developing tooth.endolymphatic sacThe expanded distal end of the endolymphatic duct.heart sacThe pericardium.hernial sacIn the peritoneum, a saclike protrusion containing a herniated organ. See: herniaHilton's sac See: Hilton, Johnlacrimal sacThe upper dilated portion of the nasolacrimal duct situated in the groove of the lacrimal bone. The upper part is behind the internal tarsal ligament. It is 12 to 15 mm long. lesser peritoneal sacOmental bursa.peritoneal sacThe enclosed, transparent mesothelial sac that is squeezed between the abdominal wall and the abdominal viscera.vitelline sacYolk sac.yolk sacIn mammals, the embryonic membrane that is the site of formation of the first red blood cells and the cells that will become oogonia or spermatogonia. Synonym: vitelline sac See: embryo for illus |