In conventional IVF, a sperm penetrates an ovum through natural selection, and embryologists sort sperm for ICSI. The quality of the original ovum and sperm has the greatest effect on the quality of the fertilized egg (embryo). Therefore, the selection of superior sperm is critical for ICSI. Although sperm cells are 20-fold smaller than embryos or ova, they are observed and evaluated for ICSI using an inverted microscope at ×400 magnification usually used for observation of embryos or ova. Recently, a technique called intracytoplasmic morphologically selected sperm injection (IMSI) has attracted attention. This technique uses an inverted microscope with higher magnification and resolution than that used for ICSI, which enables embryologists to precisely observe sperm morphology, particularly the presence or absence of vacuoles in the sperm head, and to sort sperm for microfertilization. Although IMSI has some technological problems, including a narrow microscopic field due to higher magnification that leads to delicate microscopic operation, its been recognized. In the present review, we describe the status of IMSI outside Japan and the current practice of IMSI at Kiba Park Clinic.
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1 October 2008
Morphological Selection of Spermatozoa Using a High Power Microscope and the Current Status of ICSI with Morphologically Selected Spermatozoa: Basic Research and Clinical Application of IMSI
Journal of Mammalian Ova Research
Vol. 25 • No. 4
Vol. 25 • No. 4