Fig. 3

Changes in distribution of EB1 across the seminiferous epithelium in NOA vs. normal human testes. In cross-sections of normal human testes, EB1 (a microtubule plus ( +) end tracking protein, + TIP) appeared as aggregates (green fluorescence, see white arrow heads) that laid across the MT (visualized by α-tubulin, see yellow arrowheads) by binding to the microtubule ( +) ends to stabilize the MT protofilaments, preventing MTs from undergoing catastrophe, analogous to its distribution in the rat testis [38]. As such, EB1 also appeared as track-like structures (white arrowheads) and co-localized with MTs (visualized by α-tubulin staining, yellow arrowheads), consistent with its function to stabilize MTs [29, 64]. In NOA testes including MA and SCO testes, MTs appeared as truncated and collapsed structures, likely because EB1 no longer attached to the MT plus ( +) ends to maintain MT stabilization. Scale bar, 40 µm, which applies to all other micrographs