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thyroid
Normal adult size: 15-20 grams
Embryology:
Embryologic origins:
1) evagination of pharyngeal epithelium
2) some contribution from lateral pharyngeal pouches
3) decent of thyroid gives rise to thyroglossal duct: remnants of thyroid persisting along this tract:
a) lingual thyroid
b) thyroglossal cyst or nodule
c) pyramidal lobe of thyroid, a structure contiguous with the thyroid isthmus
Development:
Thyroid development:
1) ability of thyroid to concentrate & organify iodine at 10 weeks of gestation
2) T4 & TSH present in blood during 2nd trimester
3) maternal TRH crosses placenta; maternal TSH does not
4) T3 detectable late in 2nd trimester, but concentrations remain low throughout gestation
5) rT3 is increased in fetal blood & amniotic fluid relative to maternal blood
Structure:
Morphology of adult thyroid:
1) 2 lobes joined by isthmus
2) anterior & caudad to cartilages of larynx
3) fibrous septa divide gland into pseudolobes composed of
a) follicles or acini
1] cuboidal epithelium
2] colloid lumen containing thyroglobulin
b) network of capillaries surrounding follicles
4) C cells
a) source of calcitonin
b) give rise to medullary carcinoma
Related
desiccated thyroid (Armour, Niva, Apur)
thyroid function test
Specific
accessory thyroid gland, (suprahyoid/prehyoid/Wolfler gland, thyroideaima)
lingual thyroid
sheath of thyroid gland
thyroid isthmus
thyroid pyramidal lobe; Lallouette pyramid; Morgagni appendix
General
endocrine gland
References
- Harrison's Principles of Internal Medicine, 13th ed.
Isselbacher et al (eds), McGraw-Hill Inc. NY,
1994, pg 1931
- Tabatabaie V, Surks MI.
The aging thyroid.
Curr Opin Endocrinol Diabetes Obes. 2013 Review.
PMID: 23974775
Component-of
neck
Components
thyroid follicle
Images
images related to thyroid