Very interesting descriptive study regarding the dynamics of mu opioid receptor expression in the endometrium over the menstrual cycle. The function of MOR, and of the dynamic expression pattern changes over the cycle, remains yet unclear, and to my mind it would be informative at this point to delve further into the mechanism regulating these changes in expression, which might give us some clue to functionality. I would be interested to see the effect of trophic hormones, cAMP and/or steroid hormones on expression of the MOR in vitro. An additional question would be whether expression differs in ectopic vs eutopic endometrium. Looking forward to seeing more from these authors!

Thanks to the authors for this interesting work. While the data certainly suggests that there may be a link between miR200b/miR249 expression and pituitary regulation of ovarian function, I agree that future studies need to further tease out the role of miR200b and 249 in glucose metabolism and insulin resistance, as these are potential confounders. The difference in BMI between control and PCOS groups is notable. Would like to know more about the characteristics of the PCOS population studied - did they have insulin resistance? Hyperandrogenemia? is there any data that these miRs have roles in androgen metabolism? Nevertheless the research is very intriguing and I look forward to the future work as well.

Very interesting study. Could the authors comment a bit more on the context? Because ferroportin is responsible for transporting aborbed iron from inside to outside the cell, it would be interesting to know whether iron levels or levels of iron storage proteins differ between fertile and infertile women. Also, though most infertility patients were unexplained, the authors do mention that there are anovulatory and endometriosis patients in the sample - did the findings hold up when these patients were excluded? Intrigued by the findings and looking forward to future work.

Thank you to the authors for this interesting study re: the association between reduced HOXA10 and e-cadherin expression in endometrium of women with implantation failure and recurrent miscarriage. The HOXA10 null mouse does show a failure of blastocyst implantation so the decreased HOXA10 expression in RIF patients seems to make sense. The findings in women with RM are particularly intriguing and I'd love to know more about the characteristics of this group. Were these women with clinical pregnancies (u/s documented) with implantation established already? Can the authors speculate on a potential mechanism for the link between HOXA10 and RM in this scenario? I also appreciate the authors' discussion on the findings re: age. Average age of the RM/RIF group was 36 vs 30 in control. As the authors do note an association between HOXA10 expression and age I would love to see this data presented with a control group in the same age range as well.