The Mucoid Change looks under the microscope very much like edema. The cells are widely separated and the structure of the tissue is poorly defined. The cells frequently stain poorly and degenerate.

Colloid metamorphosis is the transformation of the cell substance into a thick, sticky substance known as colloid. It is found only in epithelial cells. It is not precipitated by acetic acid or by alcohol, nor does it swell in water. It usually stains orange color with Van Giesort.

It is normally found in the acini of the thyroid gland and in the pituitary body. It is frequently found in parovarian cysts, in goiter, in the tubules of the kidney in chronic nephritis, and in the prostate gland.

In cysts the colloid material is generally contained in many small cavities, giving rise to a honeycomb appearance. It may be transparent, yellowish, bluish, or chocolate color, according to other substances present.

Fig. 9. - Colloid Degeneration of the Thyroid Gland, Showing Masses of Colloid Matter in the Gland Acini (Karg and Schmorl).