Silvia Azaña, an embryologist at inviTRA, tells us in this video the reason why endometriosis affects tubal permeability:
When endometriosis is present in the fallopian tubes, it interferes with the ovarian permeability. This condition makes the passage and transport of the egg through the tube impossible when it is released from the ovary.In the same way, the passage of the spermatzoa would also be impeded, which means that fertilization cannot occur.
Furthermore, in addition to the permeability of the fallopian tubes, their capacity to capture the released oocyte may also be impaired due to the presence of pelvic adhesions caused by the presence of this endometrial tissue outside the uterus.
As a direct result, the fimbriae of the fallopian tube cannot properly interact with the egg and capture it. Therefore, the egg cannot reach the fallopian tube after ovulation. In this way, if the egg does not reach the fallopian tube, then fertilization cannot occur.
Furthermore, these adhesions caused by endometriosis can also alter the overall anatomy of the uterus, deforming it and even changing its contraction pattern. If these uterine contractions are somehow altered, it becomes difficult for the sperm to ascend to the fallopian tubes where they must arrive so that the fertilization of the egg can take place.
