[in Japanese]

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The global population growth rate represents one of the greatest threats to mankind to day. Most of today's population is concentrated in the developing countries and if left unchecked, may lead to deleterious consequences. Contraception is one of the ways of controlling population growth, however, contraceptive methods used today are not available to many individuals due to sociological, financial, or educational limitations. Immunocontraception may provide alternative to the current contraceptive methods due to its reversibility and the fact that most of the developing countries where population growth is highest, have service infrastructure for delivery of disease vaccines into which contraceptive vaccines could be incorporated. Immunizations against sperm components are feasible since antibodies can be raised against unique antigens on spermatozoa and interfere with fertilization process. However, whole sperm cannot be used for immunization as it shares some somatic epitopes that may have harmful effects. Therefore, a unique sperm specific and acceptable immunogen must be found which has no harmful effects. A number of sperm specific proteins with immunocontraceptive potential have been identified, however only a small number (Sp-10, Sp-17, FA-1, PH-20 and LDH-C4) have been extensively characterized. This article evaluates the current status of these and other sperm targeted molecules that have been proposed as candidates for immunocontraceptive vaccine. Choice of non-human primate animal models for contraceptive vaccine development is also highlighted. It further discusses the problems encountered in the development of these molecules to full contraceptive agents.

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We investigated the oocyte development in vitro from the genital ridges of 12.5 days post coitum (dpc) including premeiotic germ cells. The cultured tissues survived and the oocytes entered into growth phase. Mesonephric region with the genital ridge was vacuolated during culture in vitro. On day 18 of culture, follicle-like suructures had appeared in the cultured tissues. Morphology of oocytes isolated from the cultures was generally nomal, included the presence of a zona pellucida and had a nucleus of germinal vesicle (GV) stage. The oocyte diameter reached to 51.5±0.5 μm. Stem cell factor (SCF) did not promote the oocyte growth in this culture system. The present work showed that the oocytes developed in vitro from the 12.5 dpc genital ridges reached to the midsize whether or not SCF is added to culture.

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