Fig. 1.

Pre-therapy and post-therapy hematoxylin and eosin endometrial biopsy sections obtained from progesterone sensitive and resistant patients. All patients underwent endometrial biopsies prior to initiating treatment for initial diagnosis (pre-therapy). The same patients underwent an additional endometrial biopsy or hysterectomy during therapy to assess for progesterone efficacy (post-therapy). Pre-therapy histologic sections from patients sensitive to progesterone (a–c). Patient-matched post-therapy histologic sections showed extensive hormonal effects at the end of treatment (d–f). Pre-therapy histologic sections from patients resistant to progesterone (g–i). Patient-matched post-therapy histologic sections showed persistent complex atypical hyperplasia or hyperplasia without atypia (j–l)