Insemination and Intracytoplasmic Sperm Injection (ICSI)
ICSI
Insemination and Intracytoplasmic Sperm
Injection (ICSI):
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 resuspended 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.
The injected oocytes are then returned to the
incubator for 16 to 18 hours.
