In the IMSI (Intracytoplasmic Morphologically selected Sperm Injection) method, high magnification (> 6000 ×) is used for a thorough morphological selection of the sperm to be injected into the egg (ICSI).
Routine egg fertilization using the ICSI method is performed at relatively low magnification allowing the selection of sperm, which is both variable and visually normal in appearance. For some patients, however, such a choice may not be sufficient and it is necessary to carry out a detailed morphological analysis of the sperm. Morphological examination of motile sperm organelles (MSOME) at high magnification allows the embryologist to choose good quality, moving sperm with good quality nucleus morphology and without head vacuoles. The sperm is consequently injected into the egg within the ICSI procedure. Connecting MSOME with ICSI has given rise to the IMSI method– it has provided hope for infertile couples in instances where other assisted reproduction techniques have failed.