Objective: The molecular mechanisms underlying ectopic implantation have not been well characterized. Here we investigate HOXA10 gene expression at the site of ectopic implantation as compared with the endometrium and with the normal fallopian tube.
Study design: Northern blot analysis was used to evaluate HOXA10 gene messenger RNA level in various segments of normal pregnant and nonpregnant human fallopian tube, ectopic pregnancy, and endometrium.
Results: Normal human fallopian tube expressed minimal levels of HOXA10 gene messenger RNA in the nonpregnant state. A trend toward a greater expression of HOXA10 gene was observed in the normal fallopian tube during pregnancy, but the difference was not statistically significant (P =.075). HOXA10 gene messenger RNA expression was up-regulated significantly at the site of implantation in ectopic pregnancy (P <.001), and its expression approached that of the endometrium during normal pregnancy (P =.33).
Conclusion: HOXA10 gene expression is up-regulated at the ectopic implantation site in the fallopian tube, approaching that of the endometrium in normal intrauterine gestation. Inherently increased HOXA10 gene expression in the fallopian tube or dysregulation of HOXA10 gene expression by an abnormally implanting blastocyst may play a role in ectopic implantation.