Motile sperm organelle morphology examination: where do we stand 12 years later?

Selection of a spermatozoon presenting both motility and normal morphology is one of the main concerns in intracytoplasmic sperm injection. Spermatozoa appearing as morphologically normal at the 400× magnification could carry various structural abnormalities that could negatively influence embryo development and pregnancy establishment, but only be detected with the use of higher optical magnifications. This led to the development of motile sperm organelle morphology examination (MSOME), which can achieve magnification ranging from 6300× to 13000×. Several approaches were used to classify spermatozoa. However, the prevalence of morphologically normal spermatozoa in MSOME is low (usually less than 5%). The most striking abnormalities are vacuoles, thought to be of acrosomal and/or nuclear origin and related to failure of sperm chromatin condensation. Twelve years after the introduction of MSOME, many questions remain unsolved. A consensual definition of a ‘normal’ spermatozoon and a classification of abnor...