Clinical and Histological Findings of Non-Experimentally Induced Seminomas in Adult Zebrafish

Abstract

The present study investigated the macroscopical and histological features of two spontaneous seminomas developed by zebrafish adults. Two wild-type male zebrafish of AB/TU strain aged 2 and 3 years, respectively, developed gross pathological signs consisting of asymmetrical swollen abdomens. In one fish, named fish 1, the testicular alteration is referred to as one testis (the right one), while in fish 2, both testes were altered in their size and shape. No signs of invasion were reported. The histological analysis revealed an extensive differentiation of germ cells in various developmental stages without any oocyte, and both lesions were compatible with spermatocytic and intratubular seminomas. The etiology and the pathogenesis of the reported lesions could be related to an intricate and interconnected network of intrinsic and extrinsic factors, including the housing condition, diet, genetic background, and operator training.