Co-localisation of GDF9 with activin βA but not DAZL or BOLL prior to follicle formation.

<p>(A) Double immunohistochemistry of 18 week fetal ovary stained for GDF9 (green) and activin βA (red), thus in the merged image co-expression is yellow. Unstained germ cells are indicated with arrows. Counterstain is TOPRO. (B) Triple fluorescent immunohistochemistry for GDF9 (green), DAZL (blue) and BOLL (red) in 20 week human fetal ovary with DAPI as counterstain (grey). Split channel and merged images in (A) and (B) are shown as are merged images of non-immune serum negative control (NEG). Scale bars are 20μm. (C) Nuclear diameters of DAZL, BOLL and GDF9 stained germ cells indicates that GDF9 positive cells are significantly larger (p<0.001) than DAZL but not BOLL expressing cells (bars indicate mean ± sem). (D) Higher magnification merged image of GDF9/DAZL/BOLL immunohistochemistry showing one large primordial follicle is positive for both GDF9 and DAZL but other follicles are positive only for DAZL.