They exhibit variability between different cases; however, it is believed they are associated with the pharyngeal mucosa and muscles of the tongue. Embryological origin
During the third week of development, the thyroid gland begins to develop from the floor of the pharynx. This primordium begins as an evagination between the first and second pharyngeal grooves, relatively where the anterior two-thirds of the tongue ends. This area is known as the foramen cecum and marks the origin of the thyroglossal duct. As the developing thyroid begins to travel to its intended destination, it remains connected to the tongue via the thyroglossal duct. By the seventh week of fetal development, the thyroid reaches its final position in the neck after growing through the mesoderm and musculature of the tongue, mouth, and neck. During the eighth to tenth week, the cells of the duct normally begin growing inwards and fill the previously hollow tube, beginning from the inferior end. This inferior end of the duct will then become the pyramidal lobe of the thyroid gland. The dividing cellular cords of the tubular duct become the isthmus and lateral lobes of the gland to complete the formation of the rest of the gland.Once the thyroglossal duct involutes, the cells will begin to degenerate and disappear. However, in the case of a persistent thyroglossal duct, the tube remains hollow and continues to connect the foramen cecum to the thyroid gland. Histology
The cells of the thyroglossal duct are epithelial in origin. The cell shapes can range from columnar, to squamous, to transitional epithelium.
Heart failure may require followup with cardiology specialist, as well as medical treatment with certain medications including ACE inhibitors and diuretics. Hypogonadism may require treatment with hormone replacement therapy, which has also been shown to reduce the likelihood of developing osteoporosis later on. Liver cirrhosis may require beta blockers, a kind of antihypertensive medication. Joint pain, called arthralgias, can be treated with NSAIDs, a type of pain medication available over-the-counter. Epidemiology
The incidence of juvenile hemochromatosis in the general population remains unknown at this time, however it is very rare. It more commonly occurs in those of European descent, becoming apparent during the first to third decades of life, and affects males and females at similar rates. References
External links
GeneReview/NIH/UW entry on Juvenile Hereditary Hemochromatosis