Ektopien des Thymus und ektope Thymustumoren

Ectopic thyroid tissue results from developmental defects of the early stages of thyroid embryogenesis, in which the median thyroid anlage descends from the floor of the mouth to its final pre-tracheal position. The most common sites of ectopic thyroid tissue are accordingly in the area of the floor of the mouth and in the course of the thyroglossal duct. Rare localizations are intrathoracic (mediastinal, cardiac, pulmonary) and sub-diaphragmatic (including the adrenals, liver, gall bladder, and gastrointestinal tract). The most important differential diagnosis of ectopic thyroid is metastasis of differentiated thyroid carcinoma.By contrast, the term parathyroidectopy is not uniformly defined. Usually, the cervical-central localizations are referred to as "positional variants" (with the exception of the maxillary sinus and high parapharyngeal), whereas the cervical-lateral localizations (carotid sheath, vagus nerve) and those below the brachiocephalic and mediastinal positions (extraligamentary, aortopulmonary window, paravagal) and other rare localizations are classified as "ectopic parathyroid tissue". Parathyroidectomy is very common (in autopsy studies in 28 to 42.8% of all humans). In the context of primary hyperparathyroidism (pHPT), there is a prevalence of 6.3 to 16% of ectopic hyperfunctional parathyroid tissue (predominantly adenomas), which play an important role in the surgical treatment of pHPT.

show abstract

Fn1Regulates the Third Pharyngeal Pouch Patterning and Morphogenesis

Wang

Liang

Zhu

et al. 2022

J Dent Res

View full text Add to dashboard Cite

The parathyroid and thymus are derived from the common primordia, the third pharyngeal pouch. During their development, endodermal cells actively interact with surrounding mesenchymal cells, mainly derived from neural crest cells (NCCs). However, the mechanism by which NCCs regulate the development of the third pharyngeal pouch remains largely unknown. In this study, we showed that fibronectin 1 ( Fn1), which is synthesized by NCCs, modulates the functions of NCCs in the third pharyngeal pouch patterning and in the morphogenesis of the thymus/parathyroid. Loss of Fn1 in NCCs leads to decreased Foxn1 expression in the presumptive thymus domain at E11.5. In the mutant, we detected upregulation of the Hedgehog signaling activity in the presumptive parathyroid domain and downregulation of Bmp4 in the presumptive thymus domain. Tbx1, a Hedgehog signaling target gene in endoderm development, was ectopically expanded to the presumptive mutant thymus domain at E11.5. Fgf10, an important gene regulating the proliferation of endoderm development, was downregulated in the mutant NCCs. At later organogenesis stages, derivatives of the third pharyngeal pouch endoderm of mutant embryos were abnormal, showing conditions such as hypoparathyroidism, hypoplastic thymus, and ectopic thymus and parathyroid. These data support that Fn1 plays an important role in NCCs by regulating the patterning of the third pharyngeal pouch and morphogenesis of the thymus/parathyroid.

show abstract

Ektopien des Thymus und ektope Thymustumoren

Cited by 5 publications

References 68 publications

Pathological Aspects of Mediastinal Tumors in Children and Adolescents

Pathological Aspects of Mediastinal Tumors in Children and Adolescents

Ektopes Gewebe der Schilddrüse und der Nebenschilddrüsen

Fn1Regulates the Third Pharyngeal Pouch Patterning and Morphogenesis

Contact Info

Product

Resources

About