heart sac

sac (sak) a pouch or bag.

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air sacs  alveolar s's.

allantoic sac  the dilated portion of the allantois, becoming a part of the placenta in many mammals; it becomes the urachus in humans.

alveolar sacs  the spaces into which the alveolar ducts open distally, and with which the alveoli communicate.

Alveolar sacs (sacculi alveolares).

amniotic sac  that formed by the amnion, containing the amniotic fluid.

chorionic sac  that formed by the vertebrate chorion, surrounding the embryo, amniotic cavity, and amniotic sac and contributing to the fetal part of the placenta.

conjunctival sac  the potential space, lined by conjunctiva, between the eyelids and eyeball.

dental sac  the dense fibrous layer of mesenchyme surrounding the enamel organ and dental papilla.

endolymphatic sac  the blind, flattened cerebral end of the endolymphatic duct.

gestational sac  that comprising the extraembryonic membranes that envelop the embryo or fetus; in humans, that formed by the fused amnion and chorion.

heart sac  pericardium.

hernial sac  the peritoneal pouch enclosing a hernia.

Hilton's sac  laryngeal saccule.

lacrimal sac  the dilated upper end of the nasolacrimal duct.

yolk sac  the extraembryonic membrane that connects with the midgut; at the end of the fourth week of development it expands into a pear-shaped vesicle (umbilical vesicle) connected to the body of the embryo by a long narrow tube (yolk stalk) . In mammals, it produces a complete vitelline circulation in the early embryo and then undergoes regression.

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heart sac

n.

See pericardium.

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sac

a pouch; a baglike organ or structure. See also conjunctival sac.

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air sac

1. alveolar sac.

2. one of the large air-filled diverticula of the respiratory system of birds. See also air sacs.

allantoic sac

see allantois.

alveolar s's

the spaces into which the alveolar ducts open distally, and with which the alveoli communicate.

anal sac

see anal sacs.

endolymphatic sac

the blind, flattened cerebral end of the endolymphatic duct.

heart sac

the pericardium.

hernial sac

the peritoneal pouch that encloses a herniated viscus or mesentery.

lacrimal sac

see lacrimal sac.

paranal sac

see anal sacs.

pleural sac

the pleura-lined cavity which contains the lung.

ruminal sac

one of the dorsal and ventral sacs of the rumen which are themselves further subdivided to create a caudodorsal sac and a caudoventral sac.

yolk sac

the extraembryonic membrane connected with the midgut; in vertebrates other than true mammals, it contains a yolk mass. See also yolk sac.