Scanning electron micrographs of the same patient (no. 1) demonstrates a shift in the nidation window with exogenous hormones. (A) An abundance of fully developed uterodomes are shown on D5 of the natural cycle. (B) D8 long E2 shows retarded epithelium suggestive of pinopod appearance 1-2 days later. Note clumping of swollen microvillous tips on protruding cells and secretory droplets. Scale bar = 10 μm.