Furukawa Satoshi, Hoshikawa Yumiko, Irie Kota, Kuroda Yusuke, Takeuchi Kazuya
Biological Research Laboratories, Nissan Chemical Corporation, 1470 Shiraoka, Shiraoka-shi, Saitama 349-0294, Japan.
J Toxicol Pathol. 2021 Jan;34(1):107-111. doi: 10.1293/tox.2020-0058. Epub 2020 Oct 30.
Swim bladder tumors were detected in three out of 28 wavy medakas aged about 2 years old, all of which displayed abnormal swimming patterns caused by their spinal curvature. The tumors were located in the dorsal abdominal cavity. The swim bladder lumen was not detected in the region where it was originally assumed to be located, and that region was replaced with adipose tissue. The tumors were non-invasive, expansile, and encapsulated solid masses composed of a homogenous population of well-differentiated, densely packed, gas glandular epithelium-like cells. The tumor masses were connected to the rete mirabile, but the tumor cells did not infiltrate into them. Histopathologically, these tumors were diagnosed as adenomas originating from the gas glandular epithelium of the swim bladder. Spontaneous swim bladder tumors are rare in medaka, with an incidence of 0.02%; however, in the present study of wavy medaka, the incidence was much higher (10.7%). The long-term physical effects on the gas gland caused by swim bladder deformation considered to be a secondary effect of the spinal curvature may be an important factor in the proliferation of the gas glandular epithelium in the wavy medaka, resulting in the higher incidence of swim bladder tumors.
在28条约2岁的日本沼虾中，有3条检测出鳔肿瘤，它们均因脊柱弯曲而出现异常游泳模式。肿瘤位于腹腔背部。在原本认为鳔所在的区域未检测到鳔腔，该区域被脂肪组织取代。肿瘤为非侵袭性、膨胀性、有包膜的实性肿块，由均匀的高分化、密集排列的气腺上皮样细胞组成。肿瘤块与奇静脉相连，但肿瘤细胞未浸润其中。组织病理学上，这些肿瘤被诊断为起源于鳔气腺上皮的腺瘤。自发鳔肿瘤在日本沼虾中罕见，发生率为0.02%；然而，在本研究的日本沼虾中，发生率要高得多（10.7%）。由脊柱弯曲的继发效应——鳔变形对气腺造成的长期物理影响，可能是日本沼虾气腺上皮增殖的一个重要因素，导致鳔肿瘤的发生率更高。
