Fig. 4

Qsox2 deletion disrupted the homeostatic balance of the follicular cycle. A Hematoxylin and eosin stain of mouse ovaries showed the presence and a balanced ratio of follicles of different stages. In 20 control ovaries (from wild-type Qsox2 ^+/+) examined, the primary follicle (P), the secondary follicle (S), the antral follicle (A), and the corpus luteum (marked with asterisks) were all observed. In contrast, in both heterozygous (UBC-CreERT2 Qsox2 ^±) or homozygous knockout (Sox2-Cre Qsox2 ^−/−) ovaries, a sharp increase in the numbers of primary and secondary follicles with a drastic decrease in the number of corpus luteum were observed. B Quantification analysis showed a right-skewed distribution on the types of follicle in both heterozygous and homozygous knockout ovaries. In control ovaries, 26.1%, 33.3%, 23.4%, and 17.1% for the primary, secondary, antral follicle, and corpus luteum, respectively, were detected. However, when a single allele of Qsox2 was deleted, an increased proportion of the secondary (40.9%, + 7.5% when compared with control ovary) and antral follicles (39.1%, + 15.7% when compared with control ovary) was observed; moreover, a sharply decreased percentage of corpus luteum (4.8%, -12.3% when compared with control ovary) was also detected. These changes in the balance of follicles of different stages were more apparent in homozygous Qsox2 knockout ovaries