Cyclic variation of the cellular components in human uterine fluid

Endometrial glandular cells and mononuclear phagocytic cells dominated the samples of undiluted uterine fluid obtained at different stages of the menstrual cycle whereas granulocytes were present in much lower numbers. Mast cells were occasionally found. The number of each cell type was significantly decreased in the luteal phase as compared to the midcycle and premenstrual phases. Phagocytic activity of the mononuclear cells was also significantly decreased in the luteal phase. Low numbers of inflammatory cells and low phagocytic activity during the luteal phase may be important for survival of the blastocyst in the event of conception.