Title : Efficiency of IVF programs in women of late reproductive age when assessing the mitotic spindle
Abstract:
Late reproductive age, poor oocyte quality, and aneuploid embryos remain a pressing issue in modern IVF. The search for possible solutions to this problem continues. The quality of the embryo and its developmental potential depend on the quality of the oocyte. Typically, the cell shape, cytoplasmic structure, membrane, and polar body (a cell that separates from the oocyte during maturation) are assessed. The oocyte itself may have an abnormal shape-oval or amorphous. The cytoplasm may contain vacuoles (cavities within the cell filled with cell sap), various inclusions, and an abnormal shape. The oocyte membrane may be thick, thin, or have other abnormalities: the polar body may be absent, fragmented, or located separately from the oocyte itself. All of these abnormalities have varying degrees of impact on the embryo's subsequent development.
The oocyte also contains a very important element: the spindle. This is the cell structure that ensures the uniform distribution of chromosomes into daughter cells during cell division. When its function is disrupted, chromosomes segregate abnormally in the dividing embryo, resulting in aneuploidies in the developing embryo. It is generally accepted that in a mature oocyte, the mitotic spindle is located directly beneath the polar body. However, it is often displaced relative to the polar body by up to 40 degrees. Therefore, when injecting a sperm without visualizing the mitotic spindle, there is a risk of damaging it, which subsequently results in abnormal fertilization or failure to fertilize the eggs. We performed IVF-ICSI with spindle visualization in 22 patients of late reproductive age with cellular factors and a history of several unsuccessful IVF-ICSI attempts due to the production of aneuploid embryos in several consecutive IVF-ICSI programs.
All women were of late reproductive age. The average age was 39 ± 4 years. All patients had a normal menstrual cycle and reduced ovarian reserve. They had an average of 3 ± 1 unsuccessful IVF-ICSI programs. Each program yielded 3 ± 2 embryos. Their medical history included a history of somatic and gynecological diseases. The most common gynecological diseases were salpingo-oophoritis and uterine fibroids; extragenital pathologies included thyroid disease and chronic tonsillitis. Embryo transfer was not performed in these patients due to poor embryo quality. Prenatal genetic diagnosis yielded only aneuploid embryos. Our study yielded 5 euploid embryos from 25% of the women participating in our study. 20% of women became pregnant with embryos obtained from their own oocytes.
Conclusions: The position of the sperm during ICSI relative to the intended position of the meiotic spindle significantly affects fertilization and the quality of embryo development. Sperm placement in the M-II spindle region should be avoided. This technique increases the chances of obtaining healthy embryos, and therefore the chance of having a healthy baby!
