Abstract
This is the first report on spontaneous and experimentally induced skin neoplasms of a wild-colored, black-eyed inbred line of Mastomys natalensis (WSA Gießen).
Seventeen spontaneous skin tumors from four animals and two experimentally induced tumors from two animals were examined. Routine histology and electron microscopy were done. For the transmission experiments, tumor suspension containing tumor cells and virus was applied to the depilated and scarified skin of the lumbar region of young Mastomys natalensis. The tumor suspension contained a mixture of squamous cell carcinoma and so-called keratoacanthoma cells, both taken from another inbred line of Mastomys natalensis (GRA Gießen). Depilation was done by application of aqueous suspension of equal parts of strontium sulfide and talcum powder. Narcosis was achieved by administration of 40 mg/kg body weight of sodium pentobarbital.
The 17 spontaneous neoplasms included 13 so-called keratoacanthomas, 2 squamous cell carcinomas, I papilloma and 3 localized epithelial proliferations. The two experimentally induced neoplasms were so-called keratoacanthomas. All tumors grew slowly and neither spontaneous regression nor metastasis was seen. All neoplasms showed keratinizing epidermal proliferation, with the greatest increase in prickle cells and granulosum cells. Two spontaneous and two experimentally induced “keratoacanthomas” were observed under an electron microscope. Papilloma-like virus particles were seen in all four. The virus particles were spaced regularly throughout the nuclei of the upper part of the granulosum cells and between parts of disintegrated cells of the horny layers.
The spontaneous and experimentally induced neoplasms of this WSA-line correspond to those of another inbred line (GRA Gießen) of Mastomys natalensis. The tumors are mutually transmissible. Both inbred lines are suitable for propagation of the Mastomys natalensis papilloma virus and for studying in greater detail the biological behaviour of this oncogenic agent in epithelial skin cells.