Histology of thyroid gland with brief description of Thyroid follicle

Thyroid follicle

It is the structural unit of thyroid gland

Difference between follicular cells and para-follicular cells

Histologically Thyroid gland has following parts

1.      Capsule

2.      Parenchyma (glandular portion )

3.      Stroma  (supporting structure : connective tissue )

Parenchyma (glandular portion )

Glandular portion is formed by two types of cells

1.      Follicular cells

2.      Parafollicular cells

These two types of cells formed a definite structure known as thyroid follicle

Parts of thyroid follicle

It is a round structure contain a lumen and wall of thyroid follicle is lined by follicular cells and its basement membrane, so follicular cells are facing toward the follicular lumen.

Some whitish or pale colour bubbles are observed near the apical region of follicular cells , what is this ?

They are secretory vesicle which contain secretion of follicular cells and come out from the follicular cell into colloid by the process of exocytosis

        Again secretion of the colloid enter into the follicular cell by the process of endocytosis.   

Parafollicular cells are present peripheral part of follicular wall but within the basement membrane and it never exposed to lumen of thyroid follicle

Para-follicular cells of thyroid gland

Para-follicular cells of thyroid gland 

Topics	Para-follicular cells
Secretion	Calcitonin
Shape and size of cell	It is larger than the follicular cell and the shape of the cell is Round
Staining	It takes less staining
Exposure to luminal surface	It is never exposed to luminal surface, it is located peripheral part of thyroid follicle
Nuclei	It contain large pale stain nuclei
Golgi complex	Large amount of  golgi complex are present but  no definite location
Secretory vesicles	It contains numerous secretory vesicle present though out of the cell
rER	Present in small amount  but no definite location
Lysosome	Present but not abundant
Endocytotic vesicles or colloidal resorption droplets	No present
Microvilli	Absent
Development	4th pharyngeal pouch
Derived from	Neural crest

 

Follicular cells of thyroid gland : summary

Follicular cells of thyroid gland : summary 

Topics	Follicular cells
Secretion	T3 and T4
Shape and size of cell	It is smaller than the parafollicular cell. The shape of the cell vary according to functional state of gland: from simple squamous to low columnar epithelium
Staining	It takes more staining
Exposure to luminal surface	It is exposed to luminal surface
Nuclei	It contains comparatively dark nuclei with two or three prominent nucleoli
Golgi complex	Golgi complex are supranuclear in position
Secretory vesicles	Few and Present in apical region
rER	Present basally
Lysosome	Abundant
Endocytotic vesicles or colloidal resorption droplets	Present in the apical region of cell
Microvilli	Present
Development	Thyroglossal duct
Derived from	Endoderm