Bressler LH, Fritz MA, Wu SP, et al. - Researchers conducted the study for investigating cellular and molecular differences in the endometrium of women with suboptimal vs optimal endometrial thickening following clomiphene. Participants in the study were reproductive age women with unexplained infertility treated with 100 mg of clomiphene cycle days 3-7 who developed optimal (≥ 8 mm; n = 6, controls) or suboptimal (< 6mm; n = 7, individuals) endometrial thickness. According to results, the endometrium of suboptimal individuals vs optimal controls was characterized by a decreased volume of glandular epithelium, reduced immunostaining of markers of proliferation and angiogenesis, increased immunostaining of pan-leukocyte marker CD45 and ERβ, but declined ERαimmunostaining. Women who have suboptimal endometrial thickness after clomiphene have aberrant estrogen receptor expression patterns, architectural changes, and altered gene and protein expression, implying decreased proliferation and angiogenesis in the context of increased inflammation.