抄録
Microinsemination is good tool for analyzing the fertilizing ability of germ. And it has also become practical for conserving genetic resources, generating transgenic animals, and treating male-factor infertility. Microinsemination is not need sperm-specific properties, such as sperm motility, acrosome reaction, or sperm-oocyte membrane fusion. So we can obtain normal offspring not only with mature (epididymal) and immature (testicular) spermatozoa, but also with immature spermatogenic cells. However, we have to product normal offspring with spermatogenic cells inapplicable to natural mating or in vitro fertilization (IVF) . To obtain many zygotes and offspring, we have to select the best protocols with consideration the biochemical genetic conditions of spermatogenic cells. Mature spermatozoa carry factor (s) that activate oocytes. In mice, this sperm-borne oocyte-activating factor (SOAF) is present in testicular spermatozoa, but not in round spermatids and spermatocytes. Therefore, one method of microinsemination with mouse round spermatids, is to activate the oocytes first, and then to inject round spermatids at telophase II stage. The fertilization rate was similar when microinseminaion was carried out with mature spermatozoa, elongated spermatids, or round spermatids. However, the rate of development to normal offspring depended on the maturity of these germ cells. The high degree of skill is required for microinsemination techniques, and it also needs to be master the knowledge, the handling, and the preservation method about spermatogenic cells. Successful fertilization with round spermatid in humans been reported from a few clinics. The rapidity of human application has raised some concern about potential health hazards for the progeny. More general use of these techniques and significant advances in germ cell biology will require technical improvements.
