Fig. 4. Ki-67 immunolabelling of follicles. (A) Low-magnification view of day 12 ovary immunolabelled for Ki67 (brown) showing widespread labelling of GCs that is increased in larger follicles. Scale bar, 100 µm. (B,C) Proportion of follicles with one or more Ki67-positive GCs (B) and proportion of Ki67-positive GCs on days 12 (open bars) and 21 (hatched bars) (C). p, primordial; t, transitional; 1°, primary; 1°+, primary with a second layer forming; 2°, secondary; 2°+, secondary with third layer forming. Values are means and 95% confidence interval. Asterisks on the right shoulder of the day 12 bars denote significant differences between days 12 and 21, asterisks on horizontal lines mark significant differences between stages; *** P<0.0001, ** P<0.01, * P<0.05. In B, differences between transitional and primary, and between subsequent stages, are impossible to compare by regression when the proportion =1. (D) Primordial follicle with unlabelled GCs (arrowheads). Scale bar, 10 µm. (E) Primary follicle immunolabelled for Ki67 (green) and MCM2 (red), with nuclei labelled with DAPI (blue). Nuclei indicated by asterisks are MCM2-positive, nucleus indicated by white arrow is Ki67- and MCM2-positive; white arrowheads indicate Ki67- and MCM2-negative nuclei (DAPI only). Scale bar:10 µm.