Contribution of light and electron microscopy in the identification of morphological alterations in large Japanese field mouse (Apodemus speciosus) testes exposed to low-dose-rate radiations

Ionizing radiation affects biological systems, resulting in an increased risk of cancer and mutagenesis. Male reproductive function is sensitive to ionizing radiation, with implications connected to infertility. Following the Nuclear Power Plants accident of Fukushima in 2011, there was great attention regarding exposure damage to low-dose-rate (LDR) radiation on the reproductive system. This preliminary study aimed to evaluate the role of light (LM) and transmission electron microscopies (TEM) to identify the potential effects of LDR radio-exposure on the morphology of large Japanese field mouse (Apodemus speciosus) testes living in the Fukushima Daiichi Nuclear Power Plant (FDNPP) ex-evacuation area. After collection samples were subjected to the standard preparative for LM and TEM. The testicular parenchyma was characterized by numerous seminiferous tubules, delimited by a thick and continuous basal lamina. Basally, the germinal epithelium presented round and pale spermatogonia, primary spermatocytes; while, more adluminally, round and elongated spermatids were at different phases of development. Pale and irregular Sertoli cells were interspersed among germ cells. Occasionally, cytoplasmatic holes interrupted the nuclear membrane integrity in spermatocytes and spermatids. Residual bodies were seen at the luminal surface. In conclusion, this study suggests that LM and TEM analysis are useful in evaluating potential morphological features in the male reproductive system after LDR exposure.