Gonad histology of 19 mg/L of imidacloprid exposed group, a) increase in the number of atretic oocytes, H&E stain, b) vacuolization and unification at cortical alveoli, PAS stain, c) Distortions at karyoplasm and disruption of nucleolus organization, TB stain, d) Karyorrhexis at primary oocyte, TB stain, e) distortion at unification seminiferous tubules, PAS stain, f) sperm clusters in seminiferous tubules, H&E stain, g) hypertrophy of spermatogonia (red arrow), TB stain, h) edema in theseminiferous tubule (double headed arrow), H&E stain, Po: Primary oocyte; CoC: Cortical alveolar stage oocyte, Vo: Vitellogenic oocyte, Ca: cortical alveoli, AO: Atretic oocyte, IT: interstitial tissue, N: Nucleus, No: Nucleolus, T: seminiferous tubules, red rectangle: vacuolization and unification at cortical alveoli, arrow: karyorrhexis black rectangle: distortion at unification seminiferous tubules, black square: openings at perifollicular layers SG: spermatogonia, PST: primary spermatocyte, SST: secondary spermatocyte, STD: spermatid, S: sperm.