Intracytoplasmic sperm injection , ICSI helps men with low sperm counts
In order to achieve fertilization, there must be enough motile sperm to bind to and, subsequently, penetrate the oocyte. If the numbers of sperm are too low, then intracytoplasmic sperm injection (ICSI) is utilized. This decision to perform ICSI is made 4-6 hours after the oocyte retrieval. Factors that contribute to the decision to utilize ICSI include: the semen parameters (sperm concentration, motility, morphology, and the presence or absence of antisperm antibodies), the number of oocytes retrieved, and results from any previous IVF cycles.
In the case of insemination, the male partner’s sperm is processed to achieve an optimal concentration for fertilization of the oocytes. First, the semen is washed with a special solution and placed in a centrifuge in order to concentrate the sperm and separate them from the other components of semen. The pellet containing the sperm is then re-suspended in more of the same special solution while the remaining fluid is discarded. The oocytes are left in the cumulus-complexes, as this is required for the sperm to achieve their final activation steps.
A pre-determined concentration of sperm is placed in the drops of media that contain the eggs approximately four to six hours after the oocyte retrieval. The dishes containing the eggs and sperm are then returned to the incubator for 16 to 18 hours.
If it is determined that ICSI is the best method to accomplish fertilization, the cumulus complexes are removed from the oocytes. Removing the cumulus complex allows the embryologists to visually determine which oocytes have reached maturity and, therefore, have the capacity to become fertilized. Also, the removal of these cells is necessary for the embryologist to be able to technically perform ICSI. Only mature oocytes are injected with sperm. While observing each mature oocyte under the microscope, a single sperm is drawn into a needle and injected directly into the cytoplasm of the egg.
he injected oocytes are then returned to the incubator for 16 to 18 hours.