Intracytoplasmic sperm injection and other aspects of new reproductive technologies

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Abstract
ICSI was developed in humans in Belgium in 1992.1 The procedure involves injecting a single sperm into an egg using a micropipette one fourteenth the diameter of a human hair. The spermatozoa can be obtained either after ejaculation or after aspiration (directly) from the testis or epididymis (percutaneous epididymal sperm aspiration). The spermatozoa are prepared by washing away seminal plasma and, where possible, separating the progressive (most) motile sperm from cellular debris. Poorly motile or abnormally shaped sperm are not usually selected for injection, unless no normal appearing sperm are available in the preparation. Progressive motile sperm are slowed down in polyvinylpyrrolidine, which increases viscosity of the medium and permits a better spermatozoon selection. Immobilisation is performed by crushing the tail of the spermatozoon with the injection pipette. This disturbs the membrane potential, appears to improve fertilisation, and prevents the tail of the sperm damaging the ovum cytoskeleton. If apparently normal fertilisation occurs, up to three of the resulting embryos are transferred to the uterus 48 hours after egg collection using a standard procedure in which a fine flexible catheter containing the embryos is passed through the cervix into the uterine cavity, and the embryos are expelled in a minimal quantity of medium.