WEEK 2: PARATHYROID GLAND Flashcards
The parathyroid gland has 2 pairs.The superior and inferior parathyroid glands.State the anatomical position of each
Superior parathyroid glands:
*They are classically located near the posterolateral aspect of the superior pole of the thyroid, 1cm superior to the junction of the recurrent laryngeal nerve (RLN), and the inferior thyroid artery
* They classically lie deep to the plane of the recurrent laryngeal nerve.
Inferior parathyroid gland:
*These glands are classically located near the inferior poles of the thyroid glands, within 1-2 cm of the insertion of the inferior thyroid artery into the inferior pole of the thyroid.
* They classically lie superficial to the plane of the RLN.
* Their location is much more variable than the superior parathyroids, and can be intra-thyroidal or within the thymus or other mediastinal structures, and can even be found along the aortic arch.
State the two histological cell types of the parathyroid gland
*Chief cells
*Oxyphil cells
Describe the characteristics of the chief cells
- Arrangement in curvilinear cords
*Forms majority
*Produce the parathyroid hormone
*Smaller in size - Contain secretory granules for PTH
- More Golgi apparatus and RER
What is the other name for the chief cells of the parathyroid gland?
Principal cells
Describe the characteristics of the oxyphil cells of the parathyroid gland
*They are inactive phase of chief cells
* Increase as one ages
* Larger
*Fewer
*Usually stained
*More mitochondria, small golgi and RER
*
What is the other name for oxyphil cells of the parathyroid gland?
Eosinophil cells
What is the function of the parathyroid hormone?
Increase blood calcium levels
What hormone counteract the effect of Parathyroid hormone?
Calcitonin
What is the interesting fact about the oxyphil cells of the parathyroid gland?
They increase in number as one ages
Describe the embryology of the parathyroid gland
*Develops from the 3rd and 4th pharyngeal pouch
*The 3rd pharyngeal pouch has the dorsal wing which forms the inferior parathyroid gland and the ventral wing which forms the thymus
*The 4th pharyngeal pouch forms the superior parathyroid gland on the dorsal wing and the Ultimobranchial Body on its ventral wing
*The thymus loses it’s connection from the pharyngeal wall and descends inferiormedially to the contralateral portion in the anterior mediastinum.
- At 7th week of gestation, the inferior parathyroid gland separate from the posterior pharyngeal wall and follow the pathway of the thymus.it reaches its final destination on the posterior thyroid
*When the parathyroid loses contact with the wall of the pharynx, it attaches itself to the dorsal surface of the caudally migrating thyroid as the superior parathyroid gland.
Name the 2 structures formed by the 3rd pharyngeal pouch
Inferior parathyroid gland
Thymus
Name the two structures formed by the 4th pharyngeal pouch
Superior parathyroid gland
Ultimobranchial Body
What structure does the thymus attaches to after descending inferiormedially from the pharyngeal wall?
Contralateral portion of the anterior mediastinum
The superior an Inferior parathyroid glands are formed from the dorsal or ventral wing?
Dorsal
At what time does the inferior parathyroid gland separate from the posterior pharyngeal wall?
Week 7 of gestation
