Journal of Clinical Endocrinology and Metabolism Printed in U.S.A. Copyright © 1997 by The Endocrine Society Characterization of Integrin Expression in a Well

THE HUMAN endometrium is a dynamically active tissue in the cycling reproductive-aged woman. As in other species (1), the human endometrium undergoes spatial and temporal changes that culminate in a defined period of uterine receptivity toward embryonic implantation (2). Although the mechanism for the establishment of receptivity remains poorly understood, the timing of the “window of implantation ” in the human appears to be confined to postovulatory days 6–10, based on morphological (3) studies and data from embryo transfers in hormonally prepared recipients in the in vitro fertilization setting (4). We have suggested that defects in uterine receptivity may account for a significant proportion of failed in vitro fertilization attempts (5) as well as the underlying cause in many couples with unexplained infertility (6), endometriosis (7), and luteal phase defect (8), supported by an increasing amount of clinical data (9). Few good models currently exist, however, to study the role of specific endometrial proteins in human implantation. Although numerous endometrial cancer cell lines have been established and characterized, the Ishikawa cell line