Effect of knock-down in the expression of genes coding for seven NRs (E75, HR3, EcR, USP, SVP, FTZ-F1 and HR4) on oocyte maturation. dsRNA of seven NRs or malE was injected into newly emerged females and ovaries were dissected at four days after injection, processed and images were captured using a scanning electron microscope as described in Materials and Methods section.