Fig. 1

Exogenous TTX administration significantly elevated the tissue TTX level of Takifugu flavidus. A Different tissues of TTX amount after intramuscular injection of TTX of Takifugu flavidus. B hematoxylin–eosin staining and TTX immunofluorescence histochemical observation of gonads after intramuscular injection of TTX. b, d, f, h, j, l are the magnifying of a, c, e, g, i, k, respectively. OG, oogonia; OC, oocyte; OVC, ovarian cavity; SG, spermatogonia; The green signals represent TTX and the blue signals represent Hoechst33258 (staining for nucleic acid), the white dotted rectangle indicates the magnified area, black arrows showed the germ cells, the white triangle arrows indicate the positive signals, the scale bar is 100, 200 and 50 μm. C, TTX positive signals statistical analysis of gonads section. Data were shown as mean ± SEM. *, indicating that P < 0.05; **, indicated that P < 0.01