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Parathyroid Glands - Anatomy & Physiology (view source)
Revision as of 18:34, 10 December 2010
, 18:34, 10 December 2010→Histology
The parathyroid glands originate from the endoderm of pharyngeal pouches III and IV. The internal gland from pouch IV, external from pouch III.
The parathyroid glands originate from the endoderm of pharyngeal pouches III and IV. The internal gland from pouch IV, external from pouch III.
===[[Parathyroid Gland - Histology|Histology]]===
===Histology===
* The parathyroids are histologically easy to distinguish from the [[Thyroid Gland - Pathology#Functional anatomy|thyroid]]. [[Image:Parathyroid Gland Active.jpg|thumb|right|350px|©RVC 2008]]
** The thyroid has a characteristic follicular structure.
** The parathyroid consists of densely packed cells, of two types:
**# Chief cells (Principal Cells)
**#* Are the predominant cell type
**#* Stain darker when active
**#* Are smaller than oxyphil cells
**#* Manufacture Parathyroid Hormone (PTH)
**# Oxyphil cells
**#* Are fewer in number than chief cells
**#* Stain lighter
**#* Are larger than chief cells
**#* Have unknown function
* Grossly, the parathyroids are difficult to differentiate from thyroid tissue or fat.
** A parathyroid gland may be accidentally removed during thyroidectomy. Care must therefore be taken if the second thryoid is removed to leave the parathyroid intact, otherwise [[Parathyroid Glands - Pathology|hypoparathyroidism]] may ensue.
====Histology Gallery====
<center><gallery>
Image:Parathyroid Gland Low power.jpg|<p>'''Parathyroid Gland Low Power 1'''</P><sup>©RVC 2008</sup>
Image:Parathyroid Gland Low Power 2.jpg|<p>'''Parathyroid Gland Low Power 2'''</P><sup>©RVC 2008</sup>
Image:Parathyroid Gland Active.jpg|<p>'''Parathyroid Gland with active Principal Cells'''</P><sup>©RVC 2008</sup>
Image:normalparathyroid.jpg|<p>'''Normal Parathyroid Gland'''</P> <sup> Image courtesy of of Biomed Image Archive.</sup>
</gallery></center>
===Blood Supply and Innervation===
===Blood Supply and Innervation===