Localization of leukemia inhibitory factor in human endometrium during the menstrual cycle.

Leukemia inhibitory factor (LIF) has been shown to be imperative for the implantation of mouse blastocysts. The objective of this study was to examine the pattern of LIF protein in the human endometrium during the menstrual cycle. A low level of LIF was detected in endometrial glands during the proliferative phase. During the luteal phase, LIF staining in the glands appeared stronger in the mid- and late luteal phase than immediately after ovulation. However, a low level of LIF was detected in the stromal cells during the early and midproliferative phase, while only a minimal level was observed during the late proliferative and luteal phases.