OVERVIEW 
The Registry of Tumors in Lower Animals (RTLA) facilitates the 
study of neoplasms and related disorders in invertebrate and poi- 
kilothermic vertebrate animals by serving as a specimen depository, 
a diagnostic center, an information center and a collaborative 
study group to help understand the nature of contributed material. 
Of two-hundred-two new accessions, 84 had one or more 
neoplasms. Sixty-four of these were from bony fish, eleven from 
reptiles, seven from amphibians and one each from a shark and an 
insect. Twenty-one were experimentally induced. The neoplasms had 
arisen in every tissue system except respiratory which has tradi¬ 
tionally had few tumors. 
Most frequently represented were liver tumors which occurred 
in various species under widely different conditions, including 
specimens from the historic experiments of the early 1960’s in 
which the late Dr. Mearl F. Stanton first demonstrated that small 
aquarium fish such as the zebra danio, Brachydanio rerio , (RTLA 
2571, 2573) and the guppy, Poecilia reticulata , (RTLA 2572) could be 
used to demonstrate hepatocarcinogenicity of mammalian carcinogens. 
Subsequently a number of other species of small fish (including 
topminnow, rivulus, medaka, platyfish, Amazon molly, fathead min¬ 
now, mudminnow, sheepshead, sheepshead minnow, gulf killifish) have 
been tested, some with excellent success, to a range of carcinogens 
including several nitrosamines, polynuclear aromatic hydrocarbons 
and aflatoxin. This whole field was the subject of the National 
Cancer Institute sponsored "Symposium on the Use of Small Fish Spe¬ 
cies in Carcinogenicity Testing" organized by K. L. Hoover, J. C. 
Harshbarger, C. J. Dawe and J. A. Couch and held in December 1981 
(National Cancer Institute Monograph, in press). 
Other accessions with induced liver neoplasms include 
incipient hepatocellular carcinoma and hemangioendothelioma in 
sheepshead, Archosargus probatocephalus , (RTLA 2420-2423; B. J. 
Martin) exposed to benzidine; hepatocellular carcinoma in a series 
of rivulus, Rivulus marmoratus , (RTLA 2429-2438; M. P. Chasar) ex¬ 
posed to diethylnitrosamine; and hepatocellular carcinoma in a 
tiger salamander, Ambystoma tigrinum , (RTLA 2543; F. L. Rose) ex¬ 
posed to perylene. Other salamanders in this series, e.g., RTLA 
2541 and RTLA 2546, had developed epidermal papillomas as had 
RTLA 2564 contributed by R. S. Anderson who is studying the me¬ 
tabolism of perylene by salamanders (Anderson, R. S., J. E. D66s, 
and F. L. Rose. Differential ability of Ambystoma tigrinum hepatic 
microsomes to produce mutagenic metabolites from polycyclic aro¬ 
matic amines. Cancer Lett., in press). 
Accessions with liver tumors from specimens in natural 
habitats included hepatocellular carcinoma in bream, Abramis 
brama , (RTLA 2386, 2388; contributed by W. Slooff) from the Rhine 
