[Xanthoid corpuscles in the cytoplasm of rat kidney tubule epithelium]

In older male rats we found fuchsinophilic granula which appeared both singly and in bale-shaped arrangements in the cytoplasm of the epithelias of proximal, subcapsularly located renal tubuli. In its further development it became apparent that they formed small round-shaped clusters which stained with buffered thionine. These clusters finally united to larger ovoid or cone-shaped homogen formations which detached from cytoplasm and appeared unobstructedly in the lumen of canaliculi and in deeper nephron sections, too. The reason why the authors named these formations "xanthoid" is attributable to their yellowish color. They consist of proteoglycans, are PAS-negative, and resistant to oxidation and lipoid solvents. They appeared both in male rats investigated in a series of toxological tests and in control animals. Female animals were not investigated. In test series carried out later, they could not be found for which reason further investigations were not possible.