(A) A mixture of anti–miRNA17-5p and let7b oligonucleotides and transfection reagent, or transfection reagent only, were injected into the right or left ovarian bursa of Dicer^+/+ mice, respectively, and the patterns of type IV collagen in the CLs were examined as described in the legend of Figure 6B. A representative result from 3 independent mice is shown. (B) Anti–miR17-5p and let7b oligonucleotides enhanced the expression of TIMP1 in the ovaries in vivo. TIMP1 protein expression in the ovaries of mice injected with 2 anti–miR17-5p plus anti-let7b oligonucleotides. SVEC lysates were used as positive control for the detection of TIMP1. GAPDH was used as a loading control. (C) Serum progesterone levels were modified in miRNA precursors or anti-miRNA inhibitor–injected mice. Dicer^d/d mice injected with a mixture of miRNA17-5p and let7b precursors into both side ovaries [(d/d) + miRNA precursors] had greater serum progesterone levels than did Dicer^d/d mice (d/d) until day 5.5 of pregnancy. In contrast, Dicer^+/+ mice injected with a mixture of anti–miRNA17-5p and let7b inhibitors into both ovaries [(+/+) + miRNA inhibitors] had lower serum progesterone levels than did Dicer^+/+ mice (+/+). The serum progesterone levels of Dicer^+/+ mice injected only with transfection reagents into both side ovaries are also shown [(+/+) + mock]. Serum progesterone levels were determined by ELISA on days 1.5, 3.5, 5.5, and 7.5 of pregnancy and expressed as mean ± SD (n = 3 in each group). A graph of results until day 5.5 is shown in the inset.