I. THYROID

Human Thyroid (H&E) [#114]: Shows cyst-like follicles that are lined by a layer of cuboidal or columnar cells. The follicles are filled with colloid. The colloid is primarily composed of a glycoprotein called thyroglobulin. Thyroxin (T4) and triiodothyronine (T3) are an integral part of thyroglobulin and are stored as such until required for release into the blood stream via follicular cells. Parafollicular (C) cells constitute only a very small population of cells that are difficult to identify in this H & E preparation. They may be recognized by their large size, light staining cytoplasm and inter-(para-) follicular position. Consider the changes in the follicles (shape of follicular cells, amount of colloid, number of reasorption vesicles) in an hyperactive or an hypoactive thyroid gland.

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	Slide Text I. THYROID Human Thyroid (H&E) [#114]: Shows cyst-like follicles that are lined by a layer of cuboidal or columnar cells. The follicles are filled with colloid. The colloid is primarily composed of a glycoprotein called thyroglobulin. Thyroxin (T4) and triiodothyronine (T3) are an integral part of thyroglobulin and are stored as such until required for release into the blood stream via follicular cells. Parafollicular (C) cells constitute only a very small population of cells that are difficult to identify in this H & E preparation. They may be recognized by their large size, light staining cytoplasm and inter-(para-) follicular position. Consider the changes in the follicles (shape of follicular cells, amount of colloid, number of reasorption vesicles) in an hyperactive or an hypoactive thyroid gland.