Histology of thyroid and parathyroid, tongue

ANATOMY

1. Thyroid & parathyroid

2. Capsule Connective septa Lobule Parenchyam of the thyroid is formed by – thyroid follicle; ( para follicular cells)

3. Thyroid follicle Functional unit of the thyroid Spherical/cystic Central colloid core Single layered epithelium Connective tissue around Follicular cells contain – fenestrate capillary plexus, lymph plexus and sympathetic nerve fibers

4. Thyroid follicle at different levels of activity State of the follicle Lining epithelium Amount of colloid Inactive/ resting Squamous Abundant Active Cuboidal Moderate Highly active Low columnar Scanty

5. C( clear ) cells or parafollicular cells Polyhedral cells with oval nucleus Paler & larger than thyroid follicular cells present between basement membrane and the follicular cell Secrets : T hyrocalcitonin which lowers the blood calcium level.

6. Parathyroid gland Capsule Parenchyma of the gland consist of two types of cells Chief (principal ) cells Oxyphil cells(stained with acid dye)

7. Chief cells: Most numerous Shape: polygonal and centrally placed nucleus Size: smaller Slightly eosinophilic Synthesizes: PTH

8. Oxyphil cells: Appear s just before puberty Less numerous than chief cells. Larger than the chief cells Deeply acidophilic Function is not known.

9. Thank u……..