NEW CLASSIFICATION OF SPERM MORPHOLOGY BEFORE ICSI AT MAGNIFICATION OF X6000
Abstract
Background. At conventional ICSI, sperm to be injected into the oocyte is chosen at magnification of 400 times which does not permit abnormalities of fine sperm structures to be seen. By using a new method, intracytoplasmic morphologically selected injection (IMSI), motile sperm with a normal head, base and no vacuoles present in the head can be selected at magnification of 6000 times. Vacuoles in the sperm head reflect the damage of nucleus and/or DNA (fragmented or single-stranded DNA). Spermatozoa with vacuoles in the head have lower fertilization capacity and lead to abnormal embryo development, unsuccessful implantation, or spontaneous abortion.
Methods. The aim of this study was to evaluate the percentage of men with abnormal sperm morphology (teratozoospermia) included in the ICSI programme, in which it is possible to find a morphologically normal sperm without vacuoles in the head using IMSI method. In each selected sperm we evaluated the morphology of head (normal = 2 points), base (normal = 1 point) and presence of vacuoles in the head (one small or no vacuoles = 3 points). Totally normal sperm (or with one small vacuole in the head) was allotted 6 points. According to this evaluation, sperm were divided into three classes: class I (6–4 points), class II (3–1 points) and class III (0 points). Sperm of class I and II were suitable for injection into the oocyte, whereas sperm of class III were not.
Results. Before ICSI, the prepared semen of 13 patients which had teratozoospermia (alone or in combination with other semen abnormalities) was evaluated by the IMSI method. Sperm of class I was found in 5 men (38 %), and sperm of class II in the remaining men (62 %). Sperm of class III was found in all men. On average, 0.7 sperm of class I and 6.1 sperm of class II per man with teratozoospermia were found.
Conclusions. Morphologically normal sperm without vacuoles in the head can be found in less than half of men undergoing the ICSI programme. Further research will show, whether it is possible to improve the clinical results of the ICSI method by the sperm selection with the IMSI method.
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