Schlumberger and Lucki — Tumors in Fishes 



689 



tissues. The authors believe that the occurrence of 

 the tumors among inbred trout of all ages in a single 

 hatchery suggests that hereditary factors may play 

 a role in the genesis of the neoplasm. 



Abstracts of other reported cases of toaioni 

 of Nervous Tissaca 



Thomas, 1927 a: A tumcv, the sik of a fetal head, 

 projected from the lateral body wall in the anal region 

 of a codfish Gadus morhua. Histologically, the neo- 

 plasm consisted of fibrillar tissue among which were 

 scattered islands of ganglion cells. The author believed 

 the fibrillar tissue represented a syncytium of Schwann 

 cells. 



Takahashi, 1929: Adjacent to several of the thoracic 

 vertebrae in a plaice Limunda yokohamae was a tumor 

 4 z 2 z 2.5 cm. The growth was soft, gray, and in- 

 filtrated the adjacent tissue. It consisted of myelinated 

 nerve fibers among which were many glial and nerve 

 cells. The nerve cells were very large, with relatively 

 small nuclei bearing large nucleoli. The anatomic posi- 

 tion and histologic character of the tumor point to an 

 origin in a spinal ganglion. 



Thomas, 1932 c: An adult gilthead Spams auratus 

 bore a very large tumor that reached from the anterior 

 margin of the orbit to the mazilla. Extensive destruc- 

 tion of the nasal and ethmoid bones had taken place; 

 the overlying skin was ulcerated. Epithelial rosettes and 

 acini were present in some regions, lending a pseudo- 

 cystic appearance to the tissue. Many of the acini were 

 Uned by columnar cells that frequently bore tufts of 

 dlia. Among the connective tissue trabeculae were 

 islands of nerve cells that gave origin to neurofibrils, 

 which could be traced throughout the section. The 

 author identified the tumor as a neuroepitheli<Hna of the 

 olfactory plate. 



Haddow and Blake, 1933: A tumor that occupied 

 almost the whole thickness of the distal end of the 

 trunk was found in a flatfish Lepidorhombus megastoma. 

 Site of origin could not be determined accurately, but 

 it apparently lay in the position of a spinal ganglion. 

 The tumor was composed of a fibrillar groundwork of 

 nervous tissue containing scattered groups of ganglion 

 cells. Osmic acid preparations demonstrated the neuro- 

 fibrils as nonmedullated. The ganglion cells were im- 

 perfect, degenerated, and vacuolated, possessing bipolar 

 continuity with the nerve fibers of the tumor substance. 



PiccHi, 1933: A tumor, the size of a pea. occupied 

 the region of a caudal vertebra in a large goldfish Cans- 

 sius tturaius. In the periphery of the growth there was 

 a numy-layered capsule of pigmented cells; the central 

 region was composed of long fine fibrils that did not 

 stain with van Gieson's reagent; blood vessels were 

 scarce and thin-walled. The author identified the tumor 

 as a Khwannoma. The growth did not recur after it 

 was removed. Pieces of the tumor were injected into 

 various cold-blooded animals — fishes, frogs, and sala- 

 manders, but in none was there any evidence of growth. 



HAMARTOMA 



Tumors arising in developmental faults have been 

 recorded only twice in fishes. However, U dioald 

 be noted that grossly abnormal development is not 

 infrequently observed among fishes raised in hatch- 

 eries (124). Similar anomaUes have been rq;xNted 

 in amphibians (125, 181) and reptiles (34, 75). 



Charlton observed a mackerel Scomber scomtbrms 

 in which no pineal organ could be identified and the 

 area was occupied by a series of epithelial f<^ds. In 

 5 or 6 places, bead-like masses of hyaline cartilage 

 were found among the epithelial cells. The author 

 identified the lesion as a chondro-epithelioma that 

 had destroyed the pineal body but caused little dam- 

 age to the brain. A tissue malf(mnation, thb lesifMi 

 may perhaps be classified as a hamartoma. 



Labbe, in 1930, found a whiting Merlangus mer- 

 langus in which the normal horizontal convolutions 

 of Uie intestine were absent, their place being occu- 

 pied by a tiunor. The latter consbted of embryonic 

 epithelial cells separated by connective tissue trabe- 

 culae that were poorly vascularized. The author con- 

 cluded that this was a tumor of embryonic cell rests, 

 i.e., of celb which would have formed the mucosa of 

 the intestine if differentiation had proceeded nor- 

 mally. Like the preceding case, this may represent a 

 local tumor-like developmental fault. 



TAXONOMIC DISTRIBUTION OF 

 TUMOR-BEARING HSHES 



It is well known that there are distinct differences 

 in natural susceptibility to neoplastic growth for 

 different tazonomic groups. For ezample, Ratdiffe 

 (168a) in his extensive sur\'ey of tumors in captive 

 wild animals and birds found that in manmials the 

 digestive tract, and in birds the genito- urinary or- 

 gans, are the predominant sites. Moreover, the organ 

 incidence of the various orders, families and apedes 

 also showed interesting differences. Thus, among 

 birds the grass parrakeet, MelopsUtacus undwUhu, 

 had by far the highest incidence of renal tumors. 

 Many other comparable examples are given for do- 

 mesticated animals by Fddman (46a). 



In fishes, differences in organ or tissiie suscqHi- 

 bility are also present. As a class, they are more sus- 

 ceptible to neoplastic processes of their connective 

 tissues than of other tissues. Tumors of nerve dkcath 

 are more common in the snapper family, Litiiamidae, 

 than among other groups; epitiieUoma of the Up Is 

 the most frequent tumor of a spedes of catfish, 

 Amehtrus nebtdosus, and multiple osteoma of the 

 haemal spines more often affects the red tal. Ptro- 

 jiNNMi MM/0r. than other spedes. However, the same 

 kind of tumor may be found in different spedes of 



