Micromanipulation involves a well-integrated set of technologies in assisted reproductive technology (ART). Its applications are diagnostic as well as therapeutic, and it is practiced in mature gametes and all stages of preimplantation embryos. It is used in biopsy for preimplantation genetic diagnosis (PGD), intra-cytoplasmic sperm injection (ICSI), assisted hatching, and in other more controversial areas such as egg freezing via zygote reconstitution, cryopreservation of isolated testicular spermatozoa, and cytoplasmic or mitochondrial transfer for reversal of cytoplasmic and potentially nuclear incompetence (1–6). In this context, it becomes increasingly difficult to discuss micromanipulation as a separate subject. . | _14__ Micromanipulation as a Clinical Tool Jacques Cohen Tyho-Galileo Research Laboratories and Reprogenetics West Orange New Jersey . INTRODUCTION Micromanipulation involves a well-integrated set of technologies in assisted reproductive technology ART . Its applications are diagnostic as well as therapeutic and it is practiced in mature gametes and all stages of preimplantation embryos. It is used in biopsy for preimplantation genetic diagnosis PGD intra-cytoplasmic sperm injection ICSI assisted hatching and in other more controversial areas such as egg freezing via zygote reconstitution cryopreservation of isolated testicular spermatozoa and cytoplasmic or mitochondrial transfer for reversal of cytoplasmic and potentially nuclear incompetence 1-6 . In this context it becomes increasingly difficult to discuss micromanipulation as a separate subject. In fact the need for a separate assessment appears almost artificial. When different fields merge in science exciting developments can be expected. This has occurred numerous times in ART first in the integration of biochemistry and reproductive endocrinology and later when cryobiology and applied genetics emerged as tools to improve efficiency and safety. No reproductive specialist could have predicted that the field of experimental micromanipulation would have such an enormous impact on assisted reproduction less than two decades after the first relatively simple but elegant applications appeared 1-3 . Since then hundreds of thousands of 283 284 Cohen babies have been born worldwide from micromanipulative methods aimed at alleviating male infertility and enhancing implantation and the exclusion of chromosomal and single gene disorders. Some laboratories now have three or more complete stations for micromanipulation. Rather than having some embryologists sub-specialize in the area of micromanipulation the practice in some laboratories most embryologists now aim to .