Fig. 4.

GDF9 enhances the growth of both primary and early secondary follicles in vitro. a Follicles of C57Bl6 mice at postnatal days 8–12 were manually isolated and encapsulated in 0.5 % alginate and cultured in serum-free media in the presence or absence of 500 ng/ml GDF9. Scale bar, 100 μm. b Box and whisker plots indicate the median, interquartile range, and minimum and maximum values for the follicle volume fold change observed in primary (50–89 μm in diameter) and early secondary follicles (90–120 μm in diameter) in response to stimulation with GDF9 at 500 ng/ml. Follicles were isolated from 6 different mice in at least 3 different experiments with more than 60 follicles evaluated. Dashed horizontal lines indicate baseline at start of culture. *p < 0.05 in Mann-Whitney U test compared to the untreated population on the same day of culture