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Cellular origin of rat renal oncocytoma
1Institut für Experimentelle Pathologie, Deutsches Krebsforschungszentrum, Heidelberg, Federal Republic of Germany.
Abstract:
The cellular origin of the rat renal oncocytoma was studied by light and electron microscopy in rats treated with N-nitrosomorpholine. The oncocytomas which appeared as small solid masses or cysts developed from tubules lined by oncocytes. Rats treated with N-nitrosomorpholine showed a number of oncocytomas and many oncocytic tubules, the incidence of which increased with time. A small number of oncocytic tubules but no oncocytomas were observed in the oldest control rats. Two major types of oncocytes were detected in the oncocytic lesions. Whereas some oncocytes contain only small round mitochondria, most oncocytes exhibited both small and unusually large pleomorphic mitochondria. The tubular origin of the oncocytic lesions was established precisely in serial sections. Numerous transitions of both oncocytomas and oncocytic tubules into renal tubules of normal appearance indicated that oncocytic lesions developed frequently from the cortical collecting duct system, including the connecting tubule, and occasionally from the outer medullary collecting duct. Mitochondrial changes similar to those of fully developed oncocytes were recognized in principal and intercalated cells of these segments, indicating the involvement of these cell types in the genesis of the renal oncocytoma.
Insights
Rat renal oncocytomas originate from renal tubules. N-nitrosomorpholine treatment induced these tumors, revealing oncocytes with distinct mitochondrial changes, primarily from the collecting duct system.
Area of Science:
- Nephrology
- Oncology
- Cell Biology
Background:
- Renal oncocytomas are benign kidney tumors.
- Their cellular origin in rats is not fully understood.
- N-nitrosomorpholine is a known carcinogen used in experimental models.
Purpose of the Study:
- To investigate the cellular origin of rat renal oncocytoma.
- To identify the specific renal tubule segments involved in oncocytoma development.
- To characterize the cellular and subcellular changes associated with oncocytoma formation.
Main Methods:
- Light and electron microscopy were employed.
- Histological analysis of serial sections was performed.
- Rats were treated with the carcinogen N-nitrosomorpholine.
Main Results:
- Oncocytomas developed from tubules lined by oncocytes.
- Oncocytic tubules and oncocytomas increased with carcinogen dose and time.
- Two types of oncocytes were identified based on mitochondrial morphology.
- Lesions originated from the cortical collecting duct system and outer medullary collecting duct.
- Mitochondrial changes were observed in principal and intercalated cells.
Conclusions:
- Rat renal oncocytomas arise from the renal collecting duct system.
- Oncocytes exhibit characteristic mitochondrial abnormalities.
- Principal and intercalated cells are implicated in renal oncocytoma genesis.