Parathyroid glands


4 glands.

Superior parathyroid glands are derived from the 4th branchial cleft and they migrate with the ultimobranchial body to the thyroid gland near the posteriolateral projection, the tubercle of Zuckerkandl. This area is within a 1 cm radius of where the recurrent laryngeal nerve passes the tubercle.

The inferior parathyroid glands originate from the 3rd branchial cleft and they migrate with the thymus past the superior glands and lie anteroinferior to the recurrent laryngeal nerve, either on the lower pole of the thyroid, or within the thymus.

Two parathyroid glands located in the inferior poles of the thyroid and two imbedded in the superior poles of the thyroid.

The location of these glands and their number can vary considerable and sometimes the tissue can be found in the mediastinum.

Each gland is highly vascularized measuring about 3 x 6 x 2 mm.

Contain mainly chief cells with abundant Golgi apparatus and endoplasmic reticulum and secretory granules.

Oxyphil cells, larger and less abundant than chief cells, contain large numbers of mitochondria.

Oxyphil cells increases with age as few cells are present before puberty.

Oxyphil cell function unknown.

When such glands that are located on the surface of the thyroid they are at the greatest risk of inadvertent removal if not identified at the time of thyroidectomy.

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