Various tumors that developed spontaneously in p53 medaka knockouts. (a,b) The tumor that arose in the left gill of a p53
E241X/+ fish with the lymphomatous infiltrate, consistent with the diagnosis of thymic lymphoma. (c,d) Adenocarcinoma found in the right gill of a p53
E241X/E241Xhomozygous fish. (e,f) Retinoblastoma in the right eye of a p53
E241X/E241Xhomozygous fish. Note the rosette-like structures throughout the tumor. (g,h) A germ cell tumor found in the anterior upper part of the peritoneal cavity of a p53
E241X/E241Xhomozygous fish. All fish presented here died or were sacrificed at around 8 months of age. Arrowheads indicate tumors. Hematoxylin-eosin staining, original magnification: (b,d) 100×; (f,h) 10×.