Fertilization by Microinsemination

1. Presented By,
Pavithra B
II. M.Sc Biotechnology
FERTILIZATION BY
MEANS OF
MICROINSEMINATION

2. INTRODUCTION
• Micro-insemination involves sperm deposition directly into
oocytes.
• This can be by transfer of sperm (Micro-Insemination Sperm
Transfer, or MIST) or by micro-injection into the ooplasm (Micro-
Insemination Micro-Injection into Cytoplasm, or MIMIC).

3. WHY MICROINSEMINATION ?
• In couples who undergo routine in vitro fertilization (IVF), 17%
experience significant problems with fertilization and many others are
unable to have routine IVF and Embryo transfer because the quality of
their semen is too poor.
• Micro-insemination is done when spermatozoa with
• no or very poor motility,
• very low density,
• multiple defects, or
• inability to penetrate oocyte vestments.
• Micromanipulative assisted fertilization techniques have improved the
treatment of severe male factor infertility significantly.

4. HOW IT IS DONE ?
• Initially, techniques such as zona drilling and partial zona dissection, in
which a hole or slit is placed in the zona pellucida, demonstrated that
fertilization and pregnancies could be achieved with semen of very
poor quality, but successes were sporadic.
• Zona drilling with acid is not advised because of disturbances to
chromosomal kinetics.
• MIST does not result in an increased risk of chromosomal
abnormalities, than that of MIMIC.

5. • Later, subzonal injection of spermatozoa provided more consistent
results with many units reporting pregnancies; however, relatively low
rates of fertilization (14-34%) and high rates of polyspermy remained
unresolved problems.
• The latest technique, the injection of a single spermatozoon into the
oocyte cytoplasm, although technically difficult in animal models,
proved to be highly successful in the human, restoring fertilization
rates to those seen in routine IVF (65%) and producing good
pregnancy rates from transferred embryos.

6. METHODOLOGY
• Eggs and sperm are obtained by using standard methods during an in
vitro fertilization treatment cycle.
• Sperm are then prepared in a manner to select and retain only the
most active sperm in a small volume of culture medium.
• After exposing the mature eggs to an enzyme that removes the
cumulus cells which surround the egg, each egg is placed under a
microscope and held in place by gentle vacuum with a small glass tube
called a micropipette.

7. • A single sperm is then drawn up into an extremely sharp, hollow glass
needle along with a very small amount of the nutrient liquid medium.
The needle is then passed through the zona pellucida (the gel-like
substance surrounding each egg) and the cell membrane to inject the
sperm into the center of the egg by using a special microscope
assembly.

8. • Approximately 16-18 hours after ICSI, the eggs are examined under
the microscope to assess for the presence of two distinct pronuclei,
which indicates normal fertilization. Subsequent maintenance of
embryos and the performance of the embryo transfer is the same as
standard IVF.

9. RISKS OF MICROINSEMINATION
• There are many thousands of on-going pregnancies and babies born
worldwide since the introduction of ICSI.
• Unforeseen technical problems may arise which preclude successful
fertilization via microinsemination.
• The likelihood of success cannot be predicted.

10. BENEFITS OF
MICROINSEMINATION
• Microinsemination may increase the chances of pregnancy in couples
whose chance of successful fertilization through standard IVF
techniques is reduced.
• The chance of any woman giving birth to a child with congenital birth
defects in the United States is 3-4%, no matter how pregnancy is
achieved.
• Available data does not indicate any reason to expect that
microinsemination will result in increased incidence of chromosomal
abnormalities in human infants.

11. ALTERNATIVES TO
MICROINSEMINATION
• The alternatives to microinsemination include increasing the sperm
numbers that surround the egg while it is incubating in the laboratory
or, in cases of male factor infertility, the use of donor sperm.
• Increasing the sperm concentration may increase the chance of
fertilization but may have an adverse effect on the laboratory
environment of the egg (Polyspermy).

12. CONCLUSION
• Microinsemination is a procedure that can be used to increase the
chance of fertilization for a couple undergoing in vitro fertilization and
embryo transfer (IVF-ET) who may have a reduced chance of
fertilization through standard egg insemination procedures.
• Clinical situations in which the techniques of assisted fertilization may
be useful include cases of male infertility, immunological infertility, or
when there has been failure of fertilization or low rate of fertilization in
previous IVF treatment sessions.