Pathologic Anatomy of Pseudobranch Tumors in Pacific Cod, Gadus macrocephalus

• Published in: JNCI: Journal of the National Cancer Institute
• Main Authors: Alpers, C. E., Cain, B. B., Myers, M., Wellings, S. R., Poore, M., Bagshaw, J., Dawe, C. J.
• Format: Text
• Language: English
• Published: Oxford University Press 1977
• Subjects: Articles; Bering Sea; Pacific
• Online Access: http://jnci.oxfordjournals.org/cgi/content/short/59/2/377; https://doi.org/10.1093/jnci/59.2.377

Pharyngeal tumors at the locus of the pseudobranch (parabranchial body) were found at a mean frequency of 4.2% in 2,096 Pacific gray cod ( Gadus macrocephalus ) taken from the Bering Sea. The tumors, invariably bilateral and symmetrical, generally surrounded remnants of normal pseudobranch but did not invade nearby or distant organs. Cells comprising the bulk of the tumor tissue were identical to the “X-cells” previously observed in skin papillomas of pleuronectids from North American Pacific coastal waters and in skin papillomas of pleuronectids and gobles from Japanese waters. However, no papillomas were present in cod with pseudobranch tumors. In these pseudobranch tumors of cod as in skin papillomas of pleuronectids, X-cells were mostly held within meshworks of fine, electron-dense cytoplasmic processes belonging to another cell type, “envelope” (or satellite) cells. Complexes of X-cells and envelope cells formed thick sheaths around small blood vessels, giving the tumors an organoid appearance. The origin of the X-cells was indeterminate. Many of their features suggested that they are unicellular organisms, producing xenomas. Other features, notably the intracytoplasmic membrane-bound argyrophil granules, suggested that they are polypeptide hormone-producing cells, possibly stemming from chemoreceptor organs. The possibility that they are virus-transformed cells was not excluded. No virus particles were found in pseudobranch tumor.