Scanning electron microscopy Samples were washed twice in a buffer containing 0.15 mol/L of sodiumcacodylate and 3 mmol/L of calcium chloride (PH, 7.4) and once in distilled water. The specimens were dehydrated first in increasing concentrations of ethanol (70%,95%,and 99.5%) and then in acetone; they were dried in a critical-point dryer by using carbon dioxide. The specimens were mounted, coated with platinum, and examined by using a scanning electron microscope ( S-3000N, Hitachi, Tokyo, Japan). The developmental phase of the pinopode were classified. Because the pinopodes on the endometrial surface do not develop at exactly the same time the pinopodes were not evenly distributed over the endometrial surface, thus, in our study, we examined five fields each biopsy sample and analyzed the development and distribution of pinopodes. The morphology evaluation was defined as: no pinopodes,developing pinopodes,fully developed pinopodes and regressing pinopodes. The semi-quantitative evaluation was defined as following:- (0%), + (﹤20%), ++ (20-50%) and +++(>50%).