In vitro fertilization through intra-cytoplasmic morphologically selected sperm injection (IMSI) is achieved in the laboratory through Nomarski microscopy. Nomarski microscopy was developed around 1952 and is a technique of optical microscopy used to enhance the contrast in non-coloured, transparent samples. A relatively complex optical system produces an image with the object appearing black on white with a Gray background. This image is similar to that obtained with contrast microscopy used in micromanipulation, but with slight differences. In about 2001, this method first entered the field of embryology in order to improve the sperm selection in cases with abnormal sperm and low fertilisation rates in the past.