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THYROGLOSSAL DUCT

The thyroglossal duct is an embryological anatomical structure which forms the connection between the initial area of development of the thyroid gland and its final position.

The thyroid gland starts developing in the pharynx in the fetus and descends to its final position taking a path through the tongue, hyoid bone and neck muscles. The connection between its original position and its final position is the thyroglossal duct. This duct normally atrophies and closes off before birth but can remain open in some people.

Failure of the duct to atrophy can lead to thyroglossal cysts which can become infected (uncommon) and thyroglossal duct carcinoma (very rare). In the case of thyroglossal duct carcinoma, the cancerous cells are ectopic thyroid tissue that has been deposited along the thyroglossal duct and usually follows exposure to radiation.

Mammalian embryogenesis/Embryology and Fetal development - edit

Embryo/Carnegie stages: Zygote | Morula | Blastula/Blastomere/Blastosphere | Gastrula/Gastrulation | Neurula | Fetus

General: Archenteron/Primitive streak | Blastopore | Hensen's node | Germ layer (Ectoderm, Endoderm, Mesoderm) | Histogenesis | Organogenesis | Branchial arch (1st) | Branchial pouch | Meckel's cartilage | Somite/Somitomere | Thyroglossal duct | Vitelline duct

Circulatory system: Primitive atrium | Primitive ventricle | Bulbus cordis | Truncus arteriosus | Ostium primum | Foramen ovale | Ductus venosus | Ductus arteriosus | Aortic arches | Septum primum | Septum secundum | Cardinal veins

Nervous system: Neural development/Neurulation | Neural folds | Neural groove | Neural tube | Neural crest | Neuromere | Notochord | Optic vesicles | Optic stalk | Optic cup

Digestive system: Foregut | Midgut | Hindgut | Proctodeum | Rathke's pouch | Septum transversum

Urinary/Reproductive system: Urogenital folds | Urethral groove | Urogenital sinus | Kidney development (Pronephros | Mesonephros | Ureteric bud | Metanephric blastema) | Fetal genital development (Wolffian duct | Müllerian duct | Gubernaculum | Labioscrotal folds)

Uterine support: Placenta | Umbilical cord (Umbilical artery, Umbilical vein, Wharton's jelly) | Amniotic sac (Amnion, Chorion) | Yolk sac | Allantois | Trophoblast (Cytotrophoblast | Syncytiotrophoblast | Gestational sac)