Is the endometrium or oocyte/embryo affected in endometriosis?

One of the most puzzling problems of endometriosis is determining which mec hanisms link this spectrum of conditions to infertility. There is conflicti ng evidence about the effect of endometriosis on the endometrium and on ooc yte/embryo quality. Clinical studies reveal that implantation rates seem to be lower in women with endometriosis, while spontaneous abortion rates sho w variable results which are difficult to interpret due to the design of th e studies. Biochemical markers (integrins and other cell adhesion molecules ), morphological markers (pinopodes), apoptosis and ultrasound studies conf irm that not only does the endometrium from women with endometriosis behave differently from the endometrium of women without endometriosis, but ectop ic endometrium also behaves differently from eutopic endometrium, Data from oocyte donation programmes suggest that oocyte quality may be hampered in women with endometriosis, Recent reports have focused on the molecular mech anisms that may be altered, such as ovarian steroid production, or inadequa te luteal function. In this review, we analyse the most recent literature d ealing with the different mechanisms which affect the endometrium and oocyt e/embryo quality and which thereby might cause infertility.