Fig. 4

Changes in the distribution of dynein 1 and KIF15 across the seminiferous epithelium in NOA testes vs. normal human testes. In cross-sections of normal human testes, dynein 1 (green fluorescence, a MT minus (-) end directed motor protein) and KIF15 (green fluorescence, a MT plus ( +) end directed motor protein) which transported cargoes to the corresponding microtubule minus (-) end and plus ( +) near the tubule lumen or the basement membrane, respectively. Distribution of these motor proteins along the MT [red fluorescence, visualized by α-tubulin staining which aligned perpendicular to the basement membrane (annotated by dashed white line)] tracks was consistent with their distribution in the rat testis [35, 36]. Some aggregates of dynein 1 were also noted near the tubule lumen in the seminiferous epithelium of the stage VII tubules when spermiation just took place since dynein 1 was needed to transport and emptied these fully developed spermatids (i.e. spermatozoa) into the tubule lumen. However, in NOA (including MA and SCO) testes, dynein 1 and KIF15 no longer distributed along the MT tracks to support spermatid and other cellular transport (e.g., residual bodies, phagosomes). These changes thus impeded MT cytoskeletal organization, they were either extensively truncated and collapsed to the base of the tubule in SCO and MA testes of NOA patients. Scale bar, 40 µm, which applies to other micrographs