Sac

The bag-like bulging or covering of a natural cavity, hernia, or tumor. S., Air, the air cells of the lung. S., Allantoid. Synonym of Allantois. S., Amniotic, the amnion. Ss., Auditory, the rudimentary organs of hearing of the embryo of certain vertebrates. S., Dental. See Dental Sac. S., Embryonic, the sac-like stage of the embryo, which it presents early in its development, just after the abdominal plates have closed. S., Fetal. See S., Gestation. S., Gestation, the sac enclosing the embryo in ectopic pregnancy. S., Hernial, the peritoneal covering of a hernia. S., Lacrymal, the dilated upper portion of the lacrymal duct. Ss., Latex, milk-sacs, spaces containing the latex of plants. S., Omental, the sac formed between the ascending and descending portions of the great omentum. S., Peritoneal, the cavity formed by the peritoneal serous membrane. S, Pleural, the cavity formed by the pieura. S., Vitelline, the sac enclosing the vitellus or yolk in the embryo. S., Yolk. See Umbilical Vesicle.