ZBTB16 and Infertility: The infertility phenotype displayed by the Plzf d/d female mouse occurs despite exhibiting normal ovarian activity, producing pre-implantation blastocysts similar in number to the Plzf f/f mouse, and having P4 and estradiol (E2) serum levels that are equivalent to levels detected in the Plzf f/f mouse at GD 5 (Supplementary Figure S2).