thyroglossal duct

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thy·ro·glos·sal duct

a transitory endodermal tube in the embryo, carrying thyroid-forming tissue at its caudal end; normally, the duct disappears after the thyroid has moved to its definitive location in the neck; its point of origin is regularly marked on the root of the adult tongue by the foramen cecum; occasionally, its incomplete regression results in the formation of cysts along its embryonic course.
See also: pyramidal lobe of thyroid gland.

His ca·nal

(hiz kă-nal')
Structural opening in a fetus between the posterior tongue and the developing thyroid. Distal part may form a thyroidal pyramidal lobe and the proximal part is usually obliterated.
Synonym(s): Bochdalek duct, duct of His, duct of Vater, thyroglossal duct.

thyroglossal duct

A duct in the embryo that runs between the THYROID GLAND and the back of the tongue. Normally, the thyroglossal duct disappears before birth but part or all of it may persist.


a passage with well-defined walls, especially a tubular structure for the passage of excretions or secretions. See also ductus.

accessory pancreatic duct
the duct of the dorsal pancreatic primordium that opens on the minor duodenal papilla. Called also Santorini's duct or duct of Santorini.
allantoic duct
see urachus.
alveolar duct
one of the final branches of the bronchial tree consisting of a tube whose walls are composed of alveoli.
bile duct, biliary duct
the passages for the conveyance of bile in and from the liver. See also bile duct.
cochlear duct
a spiral membranous tube in the bony canal of the cochlea divided into the scala tympani, scala vestibuli and spiral lamina.
common bile duct
a duct formed by the union of the cystic and hepatic ducts. See also bile duct.
cystic duct
the passage connecting the gallbladder neck and the bile duct.
efferent duct
any duct that gives outlet to a glandular secretion.
ejaculatory duct
the duct formed by union of the ductus deferens and the duct of the seminal vesicles, opening into the prostatic urethra on the colliculus seminalis. Found in the horse and ruminants.
endolymphatic duct
a canal connecting the membranous labyrinth of the ear with the endolymphatic sac.
epididymal duct
developed from the first part of the mesonephric duct.
excretory duct
one through which the secretion is conveyed from a gland.
duct of Gartner
hepatic duct
the excretory duct of the liver, or one of its branches in the lobes of the liver. See also bile duct.
incisive duct
one of a pair of ducts perforating the palate and which communicate between the mouth and the nasal cavity; they are thought to conduct chemicals for olfactory appraisal by the vomeronasal organ.
intralobar duct
ducts within lobes which provide drainage for secretions of lobes of glands.
intralobular duct
ducts found within lobules which provide drainage for secretions of lobules of glands.
lacrimal duct
one of the excretory ducts of the lacrimal gland. See also lacrimal apparatus.
lacrimonasal duct
nasolacrimal duct.
lactiferous duct
ducts conveying the milk secreted by the lobes of the mammary gland to the lactiferous sinuses or to the teats.
lobar duct
drains the secretions from the lobes of gland, connecting with the main excretory duct.
lobular duct
drains the secretions of lobules of glands.
lymphatic duct
larger lymph drainage vessels, e.g. thoracic duct.
lymphatic duct (left)
thoracic duct.
lymphatic duct (right)
a vessel draining lymph from the cranial right side of the body, receiving lymph from the right subclavian, jugular and mediastinal trunks when those vessels do not open independently into the right brachiocephalic vein.
mammary duct
lactiferous ducts.
mandibular duct
drainage duct of the mandibular salivary gland.
mesonephric duct
see mesonephric duct.
metanephric duct
the embryonic ureter.
müllerian duct
see müllerian duct.
nasal duct
the duct leading from the lacrimal sac, opening on the floor of the nasal vestibule. Called also nasolacrimal duct. See also lacrimal apparatus.
nasolacrimal duct
see nasal duct (above).
nasopalatine duct
see incisive duct (above).
pancreatic duct
the main excretory duct of the pancreas, which usually opens with the bile duct on the major duodenal papilla; may be a single duct, or two ducts which join, or two independent ducts opening into opposite sides of the intestine. See also bile duct. Called also Wirsung's duct.
papillary d's (kidney)
the straight excretory or collecting portions of the renal tubules, which descend through the renal medulla to a renal papilla or renal crest.
papillary duct (teat)
paramesonephric duct
müllerian duct.
parotid duct
the duct by which the parotid gland empties into the mouth vestibule opposite the upper molars. See also parotid glands.
perilymphatic duct
see aqueduct of cochlea.
pronephric duct
the early embryonic duct from the primitive kidney which leads into the mesonephric duct in the embryo's later stages.
prostatic d's
minute ducts from the prostate, opening into or near the prostatic sinuses on the dorsal wall of the urethra.
salivary d's
the ducts of the salivary glands.
semicircular d's
the long ducts of the membranous labyrinth of the ear.
sublingual duct
the excretory ducts of the sublingual salivary glands.
submandibular duct
the duct that drains the submandibular gland and opens at the sublingual caruncle. Called also submaxillary duct.
submaxillary duct
submandibular duct (above).
tear duct
nasolacrimal duct.
thoracic duct
a duct beginning in the cisterna chyli and emptying into the venous system at the junction of the left subclavian and left jugular veins. It acts as a channel for the collection of lymph from the portions of the body caudal to the diaphragm and from the left side of the body cranial to the diaphragm.
thyroglossal duct
the transient, non-patent duct, from the thyroid gland to the floor of the pharynx which is the legacy of the development of the thyroid from the floor of the pharynx.
vitelline duct
see meckel's diverticulum.


pertaining to the thyroid and tongue.

thyroglossal cyst
developmental abnormality near the site of the thyroid diverticulum; may exist as a subepiglottic cyst, surrounded by thyroid follicular cells, embedded in the root of tongue; may cause inspiratory dyspnea and exercise intolerance.
thyroglossal duct
vestigial canal of the epithelial outgrowth from the floor of the pharynx that develops into the thyroid gland. Parts of the duct and accessory thyroid tissue derived from it may become cystic or undergo neoplastic transformation.