Spontaneous colon tumors in rats

Area of Science:

• Veterinary Pathology
• Gastroenterology
• Oncology

Background:

• Spontaneous colon tumors are rare in laboratory animals.
• Understanding the etiology and characteristics of these tumors is crucial for research.

Purpose of the Study:

• To document and characterize spontaneous colon tumors in male W rats.
• To investigate potential etiological factors, including bacterial involvement.
• To establish a cell line for further study.

Main Methods:

• Autopsy of approximately 3,000 male W rats.
• Macroscopic and microscopic examination of colon tumors.
• Bacteriological isolation and in vitro culture.
• Establishment of a cultured epithelial cell line from a tumor.
• Intraperitoneal transplantation of a primary tumor.

Main Results:

• Twenty-eight cases of spontaneous colon tumors were identified.
• Tumors were multiple, primarily in the proximal colon, with nodules on the serosal surface.
• Microscopic findings included hyperplastic and adenomatous polyps, with tubular adenocarcinomas invading all colon wall layers.
• Bacterial growth, including Escherichia coli and a co-dependent bacillus, was observed within neoplastic glands.
• A viable epithelial cell line was established, and transplanted tumors grew intraperitoneally.

Conclusions:

• Spontaneous colon tumors can occur in male W rats.
• Bacterial presence within tumors may play a role in their development or progression.
• The established cell line and tumor model provide valuable resources for further research into colon carcinogenesis.