This document summarizes the histology of the pituitary gland, thyroid gland, and parathyroid gland. It describes the components and characteristics of each gland, their functions, and some pathological lesions. The pituitary gland has anterior and posterior lobes that secrete hormones. The thyroid gland contains follicles made up of thyrocytes and colloid. It secretes T3 and T4. The parathyroid gland regulates blood calcium levels through secretion of PTH by chief cells. Common lesions of these endocrine glands include adenomas.

1. Histology practical 1
(Histology of Pituitary & Thyroid & Parathyroid glands)
By :
Osama Al-Zahrani
@OSAMA_Z96
&
Osama Hassan Al-Ghamdi

2. 1- Pituitary Gland
* Component & Characteristics :
1- Pars Distalis.
2- Pars Intermedia (Corticotrophs).
3- Pars Nervosa.
4- Pituicytes (Neuroglia).
5- Neurosecretory Bodies (Herring Bodies) :
A- Oxytocin.
B- Antidiuretic hormone (ADH).
* Function :
- Anterior Pituitary gland :
Synthesizes and secretes hormones.
- Posterior Pituitary gland :
Store and secretes hormones (Oxytocin & ADH) .
* Histopathological Lesion :
- Pituitary adenoma.

4. 2- Pars distalis
(Anterior Pituitary gland)
* Component & Characteristics :
1- Blood capillary (Sinusoidal).
2- Chromophobs 50%
3- Chromophils 50% (50% = 34% Acidophils & 16% Basophils ):
4- Acidophils 66% : (GH & PRL).
5- Basophils 33% :
A- Thyrotrophs : (TSH).
B- Corticotrophs : (ACTH, MSH, Lipotropic LPH)
C- Gonadotrophs : (LH, ICSH, FSH).
* Function :
Synthesizes and secretes hormones.
* Histopathological Lesion :
- Pituitary adenoma.
Blood Capillary

6. 3- Thyroid Gland & Thyroid follicle
* Component & Characteristics :
1- Capsule.
2- Interfollicular cells.
3- Thyroid follicle :
A- C-cell (Parafollicular) :
- Clear.
- Calcitonin.
- Catecholamines (Epinephrine & Nor-epinephrine).
C- Thyrocytes (Follicular cells)
D- Colloid (Thyroglobulin)
* Function :
1- C-cell :
Produces calcitonin and catecholamines.
2- Follicular cells :
Secretion of T3 & T4
* Histopathological Lesion :
1- Thyroid adenoma.
2- Hashimoto thyroiditis.
Interfollicular cells
C-cell
Thyrocyte

8. 4- Parathyroid Gland
* Component & Characteristics :
1- Thin capsule.
2- Chief (Principal) cells :
- Parathyroid hormone (PTH).
3- Oxyphil cells (acidophilic) :
- Degenerated chief cells.
- Some Parathyroid hormone (PTH).
4- Colloid (homogeneous gel).
5- Blood vessel.
* Function :
- Regulation of Ca in blood (hypercalcemic).
* Histopathological Lesion :
- Parathyroid adenoma.
Thin capsule of parathyroid gland