Intracytoplasmic sperm injection (ICSI) has been developed as an assisted reproductive technique by which a sperm is mechanically injected into the cytoplasm of an oocyte. This technique was pioneered initially in sea urchin (Hiramoto 1962), then in mouse (Lin 1966) and hamster (Ue-hara and Yanagimachi 1976). Although ICSI has been used successfully in humans throughout the world since it was first introduced clinically in 1992 (Palermo et al. 1992), ICSI in mouse proved extremely difficult, and was unsuccessful until the introduction of the piezo-driven micromanipulator in 1995 (Kimura and Yanagimachi 1995). In theory, ICSI of a single sperm, including sperm DNA and other sperm factors (Wilding and Dale 1997), whether "live" or amotile, is sufficient to derive a viable mouse. In general, ICSI results in a relatively high percentage (> 50%) of successfully fertilized embryos and liveborn offspring, all of which are likely to wean and become reproductively sound. ICSI has been used to derive normal and wildtype mice with an F1 hybrid and/or inbred background, genetically-altered strains (e.g., transgenics, knockouts), strains in which only one male of the genotype remains, and strains in which a male is unable to breed naturally either because it is too old or cannot mate successfully. The genotype and phenotype of a particular strain can be transmitted vertically with high fidelity to the next generation when derived from sperm used for ICSI. ICSI can be used in any situation in which an alternative reproductive technique (ART) is applicable or warranted. In situations in which other ARTs maybe applicable, the choice of ICSI should be based on whether it is more advantageous and more likely to result in a successful outcome, i.e., live born offspring, than when using in vitro fertilization (IVF) or artificial insemination (AI). For example, we routinely
Ming-Wen Li: Center for Comparative Medicine, School of Veterinary Medicine, University of California, One Shields Avenue, Davis, CA 95616, USA
K.C. Kent Lloyd: Center for Comparative Medicine, School of Veterinary Medicine, University of California, One Shields Avenue, Davis, CA 95616, USA, e-mail: [email protected]
Principles and Practice
Mammalian and Avian Transgenesis - New Approaches Shirley Pease and Carlos Lois (Eds.) © Springer-Verlag Berlin Heidelberg 2006
use ICSI for resurrecting strains on a C57BL/6 background from cryopre-served sperm, because, in our experience, we are more likely to achieve liveborn offspring from ICSI than from IVF. In other situations, ICSI is the only reasonable choice of ART. For example, ICSI is the only technique that can successfully fertilize oocytes using dead, or amotile sperm. ICSI is also an essential technique when only a few sperm are available, when sperm cannot penetrate the zona pellucidae or oolemma, or when the availability of sperm, such as from a single aged male of a strain, is limited.
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