thyroid colloid

anatomy

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July 14, 2026

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Thyroid colloid is the substance found within the vesicles of the thyroid gland. This colloid is primarily composed of thyroglobulin, a glycoprotein that contains the amino acid tyrosine and iodine. Within the thyroglobulin molecule, iodine is added to tyrosine to form the thyroid hormones thyroxine (T4) and triiodothyronine (T3). The thyroid gland stores these hormones within the colloid as a reserve, which is particularly important given the potential scarcity of environmental iodine. When thyroid hormones are needed, the thyroglobulin is reabsorbed into the follicular cells, where it is broken down to release the active hormones into the bloodstream.123

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thyroid gland
Anatomy of the thyroid gland
…with a fluid known as colloid that contains the prohormone thyroglobulin. The follicular cells contain the enzymes needed to synthesize thyroglobulin, as well as the enzymes needed to release thyroid hormone from thyroglobulin. When thyroid hormones are needed, thyroglobulin is reabsorbed from the colloid in the follicular lumen into the…
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…with a fluid known as colloid that contains the prohormone thyroglobulin. The follicular cells contain the enzymes needed to synthesize thyroglobulin, as well as the enzymes needed to release thyroid hormone from thyroglobulin. When thyroid hormones are needed, thyroglobulin is reabsorbed from the colloid in the follicular lumen into the…
Read More

hormone
Biosynthesis
…of a substance called the thyroid colloid. This arrangement, which provides a reserve of thyroid hormones, perhaps reflects the frequent scarcity of environmental iodine, particularly on land and in fresh water. Iodine is most abundant in the sea, where thyroidal biosynthesis probably first evolved. Although the possibility that the thyroid…
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…of a substance called the thyroid colloid. This arrangement, which provides a reserve of thyroid hormones, perhaps reflects the frequent scarcity of environmental iodine, particularly on land and in fresh water. Iodine is most abundant in the sea, where thyroidal biosynthesis probably first evolved. Although the possibility that the thyroid…
Read More