Fig 1: Isolation and characterization of chromatoid bodies (CBs) from wild-type (WT) and knock-in (KI) mice. (A) Overview of CB isolation protocol from germ cells of mouse testes. (B) Immunofluorescence staining of MVH/DDX4 (green) in the testicular tissue sections of WT and KI mice; CBs are indicated by an arrow. Scale bar, ∼25 μm. (C) Immunofluorescence staining of MVH/DDX4 (green) in the round spermatids obtained from WT and KI mice; CBs are indicated by an arrow. Scale bar, ∼10 μm. (D) Immunofluorescence staining of MVH/DDX4 as a marker showing that CBs (red) isolated from KI mice are smaller in size compared to WT. Inset shows the detail of CBs indicated by an arrow. Scale bar, ∼25 μm. (E) Electron microscopy images from round spermatids showing a lobular structure with an irregular network of the less-dense strands characteristic of the CB clearly visible in WT, while in KI, CBs are markedly reduced in size. Arrows indicate CBs and N indicates the nucleus. P-values were calculated by two-tailed Students t-test (*P < 0.05). Scale bar, ∼1 μm. (F) Western blot analysis showing the complete loss of pGRTH proteins in CBs of KI mice compared to CBs of WT mice, while the levels of MVH, MIWI (CB control), and non-phospho GRTH were unaltered. FPEL, filtered pellet.