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Fine structural aspects on the cold follicles in the aged mouse thyroid
Summary
Aging thyroids in mice show decreased TSH responsiveness and reduced iodinating capacity. This study reveals the appearance of "cold" follicles and degeneration in normal follicles in older mice.
Area of Science:
- Endocrinology
- Cell Biology
- Gerontology
Background:
- Thyroid follicle responsiveness to thyroid-stimulating hormone (TSH) and iodinating capacity change with age.
- Understanding these age-related changes is crucial for thyroid health research.
Purpose of the Study:
- To investigate age-related changes in TSH-responsiveness and iodinating capacity of mouse thyroid follicles.
- To characterize the cellular and structural alterations in aging thyroids.
Main Methods:
- Light and electron microscopy were used.
- 125I radioautography was employed to assess radioiodine uptake.
- Mice of different ages (3, 10, and 19-20 months) were studied.
Main Results:
- Young mice (3 months) exhibited high TSH responsiveness and colloid droplet reabsorption.
- Aged mice (19-20 months) showed a significant increase (approx. 20%) in TSH-unresponsive "cold" follicles.
- These "cold" follicles were characterized by large lumina, attenuated epithelial cells, and altered cytoplasmic organelles.
- Degeneration was also observed in some TSH-reactive follicles, with endoplasmic reticulum swelling and lysosome accumulation.
Conclusions:
- Aging in mouse thyroids is characterized by the emergence of TSH-unresponsive "cold" follicles.
- Degenerative changes also occur in TSH-reactive follicles during aging.
- These findings highlight significant age-dependent functional and structural modifications in the thyroid gland.