Facts about Thyroid follicle
- 10
Thyroglobulin molecules within follicular colloid undergo proteolytic cleavage by lysosomal enzymes to release individual T3 and T4 hormone molecules before secretion into bloodstream capillaries.
- 09
Peroxidase enzymes within thyroid follicle cells catalyze the iodination of tyrosine residues on thyroglobulin molecules, a critical step occurring within the follicular lumen before hormone secretion.
- 08
Iodine uptake by thyroid follicles occurs through the sodium-iodide symporter, which can concentrate iodine to 200 times higher levels than in blood plasma when thyroid stimulating hormone levels are elevated.
- 07
During thyroid follicle development, cells arrange into spherical structures within 12 to 16 weeks of fetal gestation, establishing the basic architectural unit for lifelong hormone production.
- 06
Thyroid follicles secrete thyroid hormones T3 and T4 into surrounding capillaries through their basolateral membrane at rates of approximately 80 micrograms of T4 daily in healthy adults.
- 05
Thyroid follicles are lined with a single layer of cuboidal epithelial cells that transition to squamous cells during periods of decreased hormone secretion and metabolic demand.
- 04
Follicular epithelial cells actively transport iodine from blood into thyroid follicles through sodium-iodide symporter proteins, concentrating iodine up to 20 to 40 times higher than circulating levels.
- 03
Single thyroid follicles measure between 0.2 and 0.9 millimeters in diameter, with their size directly correlating to hormone production activity and metabolic demand.
- 02
The colloid stored within thyroid follicles contains thyroglobulin protein at concentrations of 300 to 400 milligrams per milliliter, serving as the primary reservoir for iodine-containing hormones.
- 01
Approximately 20 to 40 follicles comprise each thyroid lobule, with each follicle containing 20 to 40 million thyroid cells producing hormones.