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Parathyroid gland

General

Anatomy and Histology


Reviewer: Monika Roychowdhury, M.D. (see Reviewers page)
Revised: 16 February 2013, last major update January 2013
Copyright: (c) 2003-2013, PathologyOutlines.com, Inc.

General
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● 4 glands in 2 pairs usually close to upper and lower poles of thyroid lobe
● Discovered in 1880 by Ivar Sandstrom, a Swedish medical student, (Am J Surg Pathol 1996;20:1123)
● May be found anywhere along pathway of descent of branchial pouches
● 10% have 2-3 glands; 5% have 5 glands, 0.2% have 6 glands
● Upper pair arises from fourth branchial cleft and descends with thyroid gland; usually at cricothyroid junction
● Lower pair arises from third branchial cleft and descends with thymus; usually near inferior thyroid
● Other locations: carotid sheath, anterior mediastinum, intrathyroidal; glands tend to be bilaterally symmetrical
● Stromal fat increases to 30% at age 25; percent fat is related to constitutional percent fat, but reduced in dying individuals; mean is 17% with wide variation (Hum Pathol 1982;13:717)

Drawings
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Embryological pathway of parathyroid migration, showing possible locations for lower parathyroid glands

Gross description
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● Yellow-brown, 25-40 mg each gland

Micro description
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● Composed primarily of chief cells and fat with thin fibrous capsule dividing gland into lobules
● May have a pseudofollicle pattern resembling thyroid follicles (pink material is PAS positive)

Chief cells:
● 6-8 microns, polygonal, central round nuclei, contain granules of parathyroid hormone (PTH)
● Basic cell type, other cell types are due to differences in physiologic activity
● 80% of chief cells have intracellular fat
● Chief cell is most sensitive to changes in ionized calcium

Oxyphil cells:
● Slightly larger than chief cell (12 microns), acidophilic cytoplasm due to mitochondria
● No secretory granules
● First appear at puberty as single cells, then pairs, then nodules at age 40

Water clear cell:
● Abundant optically clear cytoplasm and sharply defined cell membranes
● Chief cells with excessive cytoplasmic glycogen

Micro images
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Normal parathyroid gland


Chief cells


Oxyphilic nodule


Clear cells


Colloid type material, without oxalate crystals

Positive stains
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● Chromogranin A, glycogen, keratin, PTH

End of Parathyroid gland > General > Anatomy and Histology


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