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.