6. • Capsule
• Connective septa
• Lobule
• Parenchyam of the
thyroid is formed by –
thyroid follicle; (para
follicular cells)
7. 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
8. 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
9. 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 : Thyrocalcitonin which
lowers the blood calcium level.
10.
11.
12. Parathyroid gland
• Capsule
• Parenchyma of the
gland consist of two
types of cells
• Chief (principal )cells
• Oxyphil cells(stained
with acid dye)
14. Oxyphil cells:
• Appear s just before puberty
• Less numerous than chief
cells.
• Larger than the chief cells
• Deeply acidophilic
• Function is not known.
