Specimen:

SPECIMEN DETAILS:

Organ: Thyroid gland
Origin: Human
Staining: Toluidine blue

METHOD AND SPECIMEN:

Normal section specimen of the thyroid gland.

AIM OF THE INVESTIGATION:

Knowledge of the C-cells of the thyroid gland.

SPECIMEN FEATURES:

General: Toluidine blue is a cationic (basic) dye that has been used here to stain acidic structures. The C-cells located parafollicularly in the thyroid gland produce calcitonin, which is stored in secretory granules (special vesicles). If the calcium level in the blood rises, the vesicles are exocytosed and the calcitonin is released into the blood. Calcitonin has an inhibitory effect on osteoclasts and promotes the excretion of calcium via the kidneys. The C-cells are selectively stained blue by toluidine blue due to their specific content of acidic substances (negatively charged glycosaminoglycans and calcitonin granules).

TASKS:

• Identify the follicles with the follicular epithelium. Observe the slightly bluish-colored colloid and the strongly blue-stained C-cells.