Fig. 3.

Colocalization of TB-RBP, KIF17b, and mRNAs by in situ hybridization and immunoradioautography. Shown are TB-RBP (15-nm gold particles, solid arrowheads) and KIF17b (10-nm gold particles, open arrowheads) in mouse seminiferous tubules hybridized in situ with antisense RNA probes (large filamentous silver grains) encoding AKAP4 (a, b, d, e, and g), protamine 2 (c and f), or PGK2 (h) In early (a, step 2) and late (b, step 7) round spermatids, AKAP4 silver grains are in close association with KIF17b and TB-RBP (10- and 15-nm colloidal gold particles (a, step 2). Protamine 2-generated silver grains are also in close association with KIF17b and TB-RBP in round spermatids (c, step 7) whereas PGK2-generated silver grains are not (h, step 7). During spermatid elongation, the KIF17b gold particles gradually dissociate from AKAP4 mRNAs (d, step 9, and e, step 11) and from the protamine mRNAs (f, step 11). In late step spermatids TB-RBP also dissociates from the AKAP4 mRNAs (g, step 15) and from the protamine 2 mRNAs (data not shown). (Magnification: ×100,000.)