Fig. 1

General structures of pangolin testis and epididymis. a Similar to most known mammals, pangolin testis consisted of multi-layer spermatogenic cells surrounded in circle and formed the basic structure of testicular seminiferous tubules. Moreover, sertoli cells which is responsible for maintaining testicular structure is also present (labelled by SOX9 in green) in pangolin testis and showed a well-distributed pattern. b Pangolin epididymis showed an apparent compartmentalization separated by connective tissue that efferent duct (ED), initial segment (IS), caput, corpus and cadua epididymis can easily be distinguished. Magnified images indicated that pangolin epididymal lumen was consisted by single epithelium layer. c Quantification measurements showed the average luminal diameter of different epididymal lumen was 70.17 ± 18.9 μm, 89.87 ± 19.1 μm, 192.41 ± 39.2 μm, 257.36 ± 31.7 μm for initial segment, caput, corpus and cauda epididymis, respectively. d Masson’s Trichrome stain which specifically illustrated the presence of connective tissue showed pangolin epididymis was enriched with fibrotic tissue. L: lumen, ED: efferent duct, IS: initial segment, prox. Caput: proximal caput. Representative images were presented. At least 30 lm per epididymal segment were measured