Intracytoplasmic Morphologically Sperm Injection (IMSI)
A sperm injection (ICSI) of a specially selected single sperm directly into the mature egg is known as intracytoplasmic morphologically selected sperm injection (IMSI). IMSI is a relatively new and understudied method. Sperm with irregularly shaped heads and vacuoles (cavities) are believed to be less likely to contain normal genetic material.
IMSI uses high magnification to detect sperm defects and then chooses the most normal-looking sperm. Because sperm are so little in comparison to eggs, extreme magnification is required.
IMSI is for poor sperm counts, poor sperm morphology, and surgically removed sperm.
An embryologist prepares a fresh or frozen semen sample on the day of the surgery.
An embryologist trained in the IMSI and ICSI techniques selects a single sperm for injection under a microscope.
Following egg collection, the eggs are washed and analyzed to identify which eggs are mature enough for injection, as with standard ICSI.
The sperm is aspirated and then inserted into the chosen egg using a thin glass needle.
In an incubator, the injected eggs are cultivated overnight in marked sterile culture dishes.
IMSI procedure involves:
Step 1 - semen sample preparation
The semen sample is collected and then treated with a special solution to remove any contaminants.
Step 2 - sperm selection
These sperm have a higher pregnancy rate. Even the tiniest and most numerous vacuoles can be seen. Large vacuoles and aberrant head-size sperm are not chosen.
Step 3 - egg selection
Under ultrasound guidance, a needle is inserted transvaginally to aspirate the egg follicles and collect the eggs.
Step 4 - sperm injection
Under the microscope, the selected sperm is placed in a pipette and injected into the egg. The microinjected eggs are cultured overnight in an incubator in a sterile culture Petri plate.
In India, IMSI treatment improves the chances of embryo fertilization and development, especially in men who have had unsuccessful IVF or ICSI treatment or have a high number of defective sperm. IMSI's most notable feature is that it chooses sperm with extreme precision.