Figure 4

Localization of DNAJB13 in Sept4 -null mouse spermatids. (A) As in wild type spermatids, the annulus-like DNAJB13 staining (green, arrows) was able to be detected at the neck region of spermatids from step 9 to early step 15, but the signal intensity was low and did not change obviously compared with that of the wild type spermatids. Also as in wild type spermatids, the dot (arrowheads) was present and migrated towards the midpiece-principal piece junction. (B) In middle step 15 spermatids, DNAJB13 was undetectable at the midpiece-principal piece junction, which was easily distinguished by staining the mitochondrial sheath with MitoTracker (red). The structural defect of the spermatid caused by the absence of annulus is clearly seen in the phase contrast image. The sperm nuclei were stained with DAPI (blue). Arrows indicated the position where the annulus should be in wild type spermatids. The scale bars represent 10 μm.