To determine cell-type–specific expression of leukemia inhibitory factor (LIF) and LIF receptor (LIFR) proteins relative to formation of pinopodes in human endometrial samples.
Design
Prospective clinical study.
Setting
Hospital-based unit for reproductive health and university-affiliated reproductive research laboratories.
Patient(s)
Twenty-six healthy fertile women with normal menstrual cycles.
Main outcome measure(s)
Routine blood and urine samples were obtained, and vaginal ultrasonography and endometrial biopsy were performed. Pinopode formation and expression of LIF and LIFR were examined in endometrial samples.
Result(s)
Samples obtained during LH days 6 through 9 had pinopodes at different developmental stages. Both surface and glandular epithelial cells expressed maximal levels of LIF and LIFR protein, in biopsy samples showed fully developed pinopodes. Immunostaining of LIF was more intense in the glandular epithelium, whereas immunostaining of LIFR was most intense in the surface epithelium. Before and after the appearance of pinopodes, LIF and LIFR immunostaining was less intense or faint. Stromal endometrial cells showed faint LIF accumulation.
Conclusion(s)
The simultaneous positive spatial and temporal expression of pinopodes and LIF and LIFR proteins in endometrial samples from healthy women suggests that both molecular and structural cell changes are important in the initiation of human blastocyst implantation.
Supported by the Swedish Medical Research Council (grants 3972 and 12238), Swedish Society for Medical Research, Swedish Society of Medicine, Wallenbergs Stiftelsen, Recwood, the Ragnhild and Elsa Lundströms Minne, and a Swedish Institute scholarship to Dr. Aghajanova.
