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Histologic changes in tissue components of the hyperplastic thyroid gland during its involution in the rat
S H Wollman1, J P Herveg, O Tachiwaki
1Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892.
The American Journal of Anatomy
|September 1, 1990
Summary
Thyroid involution in rats involves progressive follicular lumen dilation and colloid accumulation after switching to a high-iodine diet. Involution leads to morphological changes, but not colloid goiters.
Area of Science:
- Endocrinology
- Histology
- Pathology
Background:
- Thyroid hyperplastic glands were induced in male Fischer rats using a low-iodine diet with thiouracil.
- This study investigates the morphological changes during thyroid involution.
Purpose of the Study:
- To examine the morphological alterations in thyroid glands during involution.
- To understand the timeline of changes following a switch to a high-iodine diet.
Main Methods:
- Rats were fed a low-iodine diet with thiouracil for 21 days, followed by a high-iodine diet for up to 180 days.
- Thyroid tissues were fixed, embedded, and examined using light microscopy.
Main Results:
- Involution showed progressive follicular lumen dilation and colloid accumulation between 1 and 21 days.
- Capillary lumens narrowed, and interfollicular matrix decreased over time.
- Disintegrating cells appeared around 15 days, but colloid goiters were not observed.
Conclusions:
- Thyroid involution involves significant morphological remodeling, including colloid accumulation and cellular changes.
- The process does not result in colloid goiters, though some follicles resemble 'cold' follicles.