- 2 - 
helminthes, a phylum at the primitive level of only two germ 
layers. The lesion was composed of pleomorphic, basophilic non¬ 
polarized ganglioneuroblast-like cells presenting mitotic figures 
of widely ranging size. 
Neural neoplasms were also well represented in fish accessions. 
CNS tumors included an astrocytoma in a pollock (RTLA 2047; D. Bucke), 
an esthesioneuroepithelioma in a goldfish (RTLA 2051; H. Wolf) and an 
epend 3 nnoblastoma in a coho salmon (RTLA 2116; Prince Mssahito). PNS 
tumors include neurilemmoma in rainbow trout (RTLA 2049; K. Wolf), 
goldfish also having polycystic kidney (RTLA 2053; S. Pullan), coho 
salmon (RTLA 2074; R. Moccia), Malabar anchovy (RTLA 2142; S. 
Radhakrishnan), lingcod (RTLA 2174; R. Warner), and brown trout (RTLA 
2217; N. Boustead); and neurofibroma/neurofibrosarcoma in striped 
mullet (RTLA 2095; N. Boustead), pink salmon (RTLA 2156; G. Bell), 
Dover sole and black cod (RTLA 2169 and RTLA 2180; R. Warner). 
An additional neural tumor, rare in mammals and never pre¬ 
viously seen in poikilotherms, was a granular cell myoblastoma in¬ 
duced in a South African clawed frog with methylnitrosourea (RTLA 
2219; W. Janlsch and Th. Schmidt). This compound also produced < 
nephroblastoma in a ribbed newt (RTLA 2182; W. JSnisch). 
Other induced neoplasms included hepatocellular carcinoma, 
renal adenocarcinoma and cyst adenoma in South African clawed frogs 
exposed to N-nitrosodimethylamine (RTLA 2123-RTLA 2126; V. V. 
Khudoley); hepatocellular carcinoma in top minnows exposed to 
dimethylbenzanthracene and diethylnltrosamine (RTLA 2145, RTLA 
2146; R. J. Schultz); and hepatocellular carcinoma in Amazon 
mollies treated with aflatoxin (RTLA 2149, RTLA 2150; A. Woodhead). 
Thyroid enlargement and ectopic thyroid in spleen occurred in 
Amazon mollies treated with anthracene (RTLA 2151-RTLA 2153; A. 
Woodhead). Thyroid enlargements also occurred in various untreated 
accessions including sheepshead minnow and darter goby (RTLA 2058 
and RTLA 2071; J. Couch), lemon shark (RTLA 2061; S. H. Gruber), 
rabbitfish and sandbar shark (RTLA 2106 and RTLA 2110; Prince 
Masahito), spiny dogfish (RTLA 2165; A. Woodhead), roach (RTLA 2188; 
W. Slooff) and coho salmon RTLA 2211, RTLA 2212; C. E. Smith). 
These cases have all been Interpreted very conservatively—mostly 
as hyperplasia—because fish seem to be especially susceptible to a 
wide variety of goitrogens. Additionally, thyroid is unencapsu¬ 
lated in bony fish, is capable of destructive infiltration into 
normal tissue when hyperplasitc, and can occur ectopically in kid¬ 
ney, spleen and other sites. The question of neoplastic versus hy¬ 
perplastic fish thyroid has been inconclusively debated most of the 
20th century and until resolved it seems prudent to interpret ques¬ 
tionable cases as hyperplastic. 
Pigment cell neoplasms of three types of chromatophores in 
reptiles and fish included erythrophoroma and melanophoroma in 
