SPONTANEOUS REGRESSIVE EPITHELIOMAS IN THE JAPANESE NEWT, CYNOPS-PYRRHOGASTER

1 January 1979

journal article
research article

Vol. 39 (6) , 1904-1910

Abstract

Spontaneous tumors in urodele amphibians were considered uncommon and this resistance was sometimes associated with the natural regenerative capacity of tissues in such species. Spontaneous, nonpigmented, benign epitheliomas were found in 44 of 1586 (2.8%) adult newts, C. pyrrhogaster, captured in central Japan. Both sexes were affected equally, usually with single tumors occurring at any epidermal site. Under laboratory conditions, these large tumors rapidly regressed or disappeared. Lesions were histologically noninvasive, hyperplastic epidermal reactions accompanied by loss of basal, subdermal melanocytes. Ultrastructurally, enlargement of intercellular spaces between tumor cells, increased pigment granules and membrane-bound cytoplasmic aggregates within the spaces, swollen rough endoplasmic reticula, degenerating pigment granules, and altered corneal cells were noted. Virus-like particles were observed in tumor cell. Preliminary attempts failed to demonstrate transmissibility of the tumor, and no new cases arose under laboratory conditions. The cause of these tumors in the Japanese newt remains unknown. If a viral agent is involved, other environmental cofactors (diet, temperature, or water constituents) are required for its expression.

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