Preface, T. Aso, et al; new aspects of the physiology and pathology of the luteal phase - an overview, H. Mori; gonadotropin receptors in human ovarian follicles and corpora lutea throughout the menstrual cycle, M. Yamoto, et al; a role for thyroid hormone in the induction of ovulation and corpus luteum function, T. Maruo, et al; modulation of progesterone secretion by androgens in porcine granulosa cell cultures, K. Tanabe, et al; association of immunoreactive-inhibin levels with luteal function, K. Andoh, et al; analysis of clinical backgrounds and pathogenesis of luteal-phase defect, K. Aisaka, et al; hysteroscopic assessment of midsecretory-phase endometrium, with special reference to the luteal-phase defect, T. Sakumoto, et al; clinical importance of endometrial histology and progesterone level assessment in luteal-phase defect, K. Kusuhara; influence of progesterone/estradiol ratio on luteal function for achieving pregnancy in gonadotropin therapy, S. Kamada, et al; factors promoting embryo implantation in in vitro fertilization and embryo transfer, H. Saito, et al; further observations on serial serum immunoreactive inhibin levels in the luteal phase and early gestation after ovarian stimulation for in vitro fertilization and embryo transfer, T. Takeuchi, et al; role of corpus luteum function in embryo implantation, T. Oda, et al.