Thyroid gland
The thyroid, located in the anterior neck, consists of two major lobes connected by a thin isthmus. The thyroid regulates basal metabolic rate by secretion of thyroid hormones stored in thyroid follicles. Follicles consist of a simple epithelium surrounding a colloid-filled lumen. A second cell type, parafollicular cells, secretes calcitonin to regulate blood calcium levels. 100x
Thyroid follicles >
Cells forming thyroid follicles are polarized to secrete thyroglobulin into the center of the follicle for storage, where it is referred to as colloid. Upon stimulation, thyroglobulin is taken up by follicular cells, broken down into triiodothyronine (T3) and tetraiodothyronine (thyroxine, T4), and released into the blood.
- Follicular cells
Cells forming thyroid follicles are polarized to secrete thyroglobulin into the center of the follicle for storage, where it is referred to as colloid. Upon stimulation, thyroglobulin is taken up by follicular cells, broken down into triiodothyronine (T3) and tetraiodothyronine (thyroxine, T4), and released into the blood.
- Thyroglobulin
Cells forming thyroid follicles are polarized to secrete thyroglobulin into the center of the follicle for storage, where it is referred to as colloid. Upon stimulation, thyroglobulin is taken up by follicular cells, broken down into triiodothyronine (T3) and tetraiodothyronine (thyroxine, T4), and released into the blood.
Stroma >
The stroma is composed of loose connective tissue that surrounds and supports the endocrine elements and the blood vessels.
Blood vessels
The stroma is composed of loose connective tissue that surrounds and supports the endocrine elements and the blood vessels.”
