A method called MSOME (high magnification Motile Sperm Organelle Morphology Examination), which allows the detailed morphological evaluation of motile spermatozoa in real time and under high magnification (6600x), was developed in 2001. With this technique, fine morphological abnormalities - mainly vacuoles in the head of spermatozoa - were detected. The use of MSOME for the detection of morphologically normal sperm for ICSI gave rise to a technique called IMSI (Intracytoplasmic Morphologically Selected sperm Injection). Higher pregnancy rates were obtained with IMSI compared to ICSI and sperm head vacuoles were found to negatively affect assisted reproduction success rates and embryo development. The use of IMSI also decreases the risk of sex chromosome aneuploidy in embryos .