Microinjection: The Latest Advance in Treating the Infertile Man
from the book How to Have a Baby:
by Dr. Aniruddha Malpani, MD and Dr. Anjali Malpani, MD.
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In patients in whom surgery needs to be performed in order to recover
testicular or epididymal sperm, it is now possible to freeze the excess sperm.
These sperm can then be thawed and used in future cycles in needed, thus sparing
the patient the need for repeated surgery for sperm retrieval.
Once eggs and sperm have been collected, the actual process of injecting a
single sperm into the egg is carried out in a laboratory. The injection is
performed on a heating stage, on a specialized inverted microscope (which allows
one to magnify details up to 400 times) equipped with Hoffman modulation
contrast optics (which enhance "optical contrast", so that the details
of the egg can be visualized easily). The precise control that is needed for
microinjection is provided by using specialized micromanipulators, which allow
one to execute very fine movements.
The eggs and sperm are manipulated using fine glass pipettes, made of thin
capillary tubing, which are even finer than a human hair. These are custom made,
the holding pipette being designed to hold a single sperm. Live sperm are placed
in a drop of viscous polyvinyl pyrrolidone (PVP) solution, which serves to slow
down the activity of the sperm. (It is helpful to slow down the sperm, so that
they can be picked up more easily by the injecting needle.) A single sperm is
then selected and its tail is pinched or broken to immobilize it. This is
usually done by crushing the sperm tail by rolling it between the injection
pipette and the base of the petri dish. It is essential to immobilize the sperm,
so that it cannot move after it has been injected into the egg. A single
immobile sperm is then picked up by sucking it into the injection pipette.
The egg is secured in place by applying gentle suction to its shell (the zona)
with a holding pipette. The sperm is then injected directly into the centre
(cytoplasm) of the egg by moving the injection pipette very precisely with the
help by movine the injection pipette very precisely with the help of the
micromanipulator into the egg, and then blowing the sperm out very gently into
the cytoplasm of the egg. In order to do this, it is important to breach the
zona of the egg and the outer membrane of the egg. The skill of the embryologist
is a critical factor in the success of the ICSI process. After injecting the
sperm, the pipette is withdrawn. Remarkably, once the injecting pipette is
withdrawn, the egg will close and assume its original shape within 60 seconds.
One can visualize ICSI as the sperm being given a "piggyback" ride
into the egg, so that what the sperm cannot accomplish on its own, the
laboratory does for it! The only requirement for ICSI is that the sperm should
be alive, and there should be as many sperm as there are eggs.
Fig 1. A view of the micromanipulator
Fig 2. A single sperm is being injected into an egg during
an ICSI procedure
Once all the eggs are injected with a single sperm each, they are placed in
the CO2 incubator, and then observed approximately 14 hours later to see if
fertilization has taken place. If fertilization has occurred, the 2-4 cell
embryos can be transferred into the wife’s uterus about 48-72 hours after
ICSI, as is done for IVF. Interestingly, embryo implantation rates in these
patients are quite high, because the wives are usually young and completely
Fertilization rates in the range of 60-80 per cent have been achieved in
experienced hands-which means, of 100 microinjection eggs about 60 form embryos
after ICSI. In fact the technology is now reliable enough to virtually guarantee
fertilization, if there are sufficient good quality eggs. The pregnancy rate in
one ICSI cycle is about 35 percent. Remarkably, the chance of achieving a
pregnancy does not depend upon the sperm count or number (since you only need as
many sperm as there are eggs!), but rather on the number and quality of eggs
retrieved, which, in turn, depend upon the woman’s age. The risk of having a
baby with a birth defect is not increased with this technique.
ICSI is very expensive at present, because of the advanced technology it
utilizes. Nevertheless, it is now available in most of India’s large cities,
and as times goes by, it is hoped that the cost of this procedure will decrease,
making it affordable for more patients.
Some IVF clinics have started performing ICSI routinely for all patients ,
instead of offering them IVF. However, this is inappropriate. ICSI should be
reserved for only two groups of patients: (1) those who have severe male factor
infertility, for whom IVF is not a treatment option; and (2) those patients
whose sperm have not been able to fertilise the eggs in an IVF cycle ( total
fertilisation failure). Remember that pregnancy rates with ICSI are no better
than with IVF, as long as fertilisation occurs.
The Risk Factor
ICSI is still a new technique, and even though more than 10,000 babies have
been born worldwide after it has come into use, and detailed studies have shown
that there is no increased risk of birth defects or genetic anomalies after
ICSI, nevertheless, it should only be reserved for those patients for whom
traditional IVF is not a valid treatment option.
It is also possible that some of the male children born as a result of this
technique may be infertile as well (for example, if the cause for the testicular
failure is a defective genetic locus, such as a microdeletion on the Y
However, for some patients with severe testicular failure, sometimes, it is
not possible to find any sperm at all as even in spite of taking multiple
testicular biopsies. In such patients pregnancies have been achieved even by
injecting round spermatids (immature precursor cells from which the sperm are
formed) from the testis into the egg. This is now an area of intense research
all over the world.
For men with no testis at all, the only technologic solution today would be
cloning using nuclear transfer technology. This involves inserting the nucleus
from an ordinary cell of the man ( which contains all his DNA) into his wife’s
unfertilised egg (the nucleus of which has been removed) and then activating it
by electrofusion. While cloning has been performed successfully in many animal
species, it has never been used for treating humans so far.
by Dr. Aniruddha Malpani, MD and Dr. Anjali Malpani, MD.
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