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A scanning and transmission electron microscopic study of urinary bladders of mice treated with 2-acetylaminofluorene
Abstract:
Urinary bladders of BALB/c male mice treated with 250 ppm of 2-acetylaminofluorene for 1, 3, 5, 7, and 14 days were examined for early scanning (SEM) and transmission electron microscopic (TEM) changes. SEM observations at days 1, 3, and 5, and TEM observations at days 1 and 3 revealed no significant changes. The bladders of the mice treated for 7 days contained an occasional focus showing irregularity in the shape and size of the superficial cells and SEM revealed ropey microridges in an occasional cell. The bladders of mice treated for 14 days had a greater irregularity of cell size on SEM. TEM changes were evident as early as 5 days with an increase in severity at 7 and 14 days. A numerical reduction of fusiform vesicles, asymmetric membrane plaques and Golgi apparatus along with an increase in membranous whorls, endoplasmic reticulum, cytolysosomes, and small rounded vesicles was evident. The study may aid in a better understanding of early morphologic changes of urothelium in response to a carcinogen.
Insights
Early exposure to the carcinogen 2-acetylaminofluorene caused subtle urinary bladder changes in mice. Morphological alterations in urothelial cells became apparent by day 7, with significant ultrastructural damage observed by day 14.
Area of Science:
- Urothelial biology
- Toxicology
- Carcinogenesis research
Background:
- The urinary bladder urothelium serves as a protective barrier.
- Understanding early cellular responses to carcinogens is crucial for risk assessment and prevention.
Purpose of the Study:
- To investigate the early morphological changes in mouse urinary bladders following exposure to 2-acetylaminofluorene.
- To characterize the temporal progression of these changes using scanning electron microscopy (SEM) and transmission electron microscopy (TEM).
Main Methods:
- BALB/c male mice were administered 250 ppm of 2-acetylaminofluorene for 1, 3, 5, 7, and 14 days.
- Urinary bladders were examined using SEM and TEM to identify ultrastructural alterations.
Main Results:
- No significant changes were observed at days 1, 3, and 5 (SEM) or days 1 and 3 (TEM).
- By day 7, SEM revealed occasional irregularities in superficial cell shape and size, with "ropey microridges" noted. TEM showed changes by day 5, worsening at days 7 and 14.
- TEM revealed a reduction in fusiform vesicles, asymmetric membrane plaques, and Golgi apparatus, alongside an increase in membranous whorls, endoplasmic reticulum, cytolysosomes, and small rounded vesicles.
Conclusions:
- 2-acetylaminofluorene induces progressive morphological changes in mouse urothelium.
- These findings provide insights into the early stages of urothelial damage and adaptation in response to a chemical carcinogen.