Fig. 3

Light microscropy (with hematoxylin and eosin [HE] staining) and transmission electron microscopy (TEM) observation of testis and epididymis of challenged and control male BALB/c mice. a, b HE staining of testis in control (non-infected) (a) and challenged (b) male mice: a the number and stucture of spermatogenic cells in control mice were normal, b the number of spermatogenic cells in challenged mice was significantly reduced and seriously exfoliated. c, d HE staining of epididymis in control (c) and challenged (d) mice: c the epididymal epithelial cell structure in control mice was completed and the lumen was filled with sperm, d the epididymal epithelial cells in challenged mice were disorderly arranged, the number of sperm in the lumen was decreased. e–j TEM observation of testis in control (e, f) and challenged mice (g–j): e, f the secondary spermatocytes (e) and sperm cells (f) of control mice show regular aspects; g–j in challenged mice, TEM images show disolution of the nuclear membrane (g), swollen mitochondria and endoplasmic reticulum dilation (h), incomplete nuclear membrane and diverse mitochondrial morphology (i), membranous structure hyperplasia (j). k–n TEM observation of epididymis in control (k) and challenged (l–n) mice. k Dense microvilli, clear nuclear membrane and normal organelles in epididymis from control mice; l–n samples from infected mice showing shedded microvilli (l), decreased number of lysosomes, endoplasmic reticulum hyperplasia and swollen mitochondria with myelinated structure (m), sperm with two tails (n). Scale bars: 10 nm. A Acrosome, EEC epididymal epithelial cell, ER endoplasmic reticulum, G Golgi apparatus, H hyperplasia, JC junction complexes, L lysosome, M mitochondria, Mi microvilli, NM nuclear membrane, S sperm, SC spermatogenic cells