Fertilization failure (complete fertilization failure or low fertilization rates) after intracytoplasmic sperm injection (ICSI) can occur in rare cases. In the majority of these cases, the unfertilized oocytes are inactivated. Assisted oocyte activation was applied as a treatment option for a case of low fertilization rate as a clinical trial. A patient with a low fertilization rate (ranging from 0% to 33.3%; mean = 17.0%) after eight previous ICSI cycles at another hospital, was diagnosed with fertilization failure. The most likely cause of fertilization failure was failure of oocyte activation. Therefore, artificial oocyte activation by strontium treatment was combined with ICSI to achieve viable fertilized oocytes. Oocytes were stimulated with strontium (10 mM SrCl(2), 60 min) approximately 30 min after ICSl. Six injected oocytes were stimulated and all were then successfully fertilized. Two blastocysts were transferred into the uterus, resulting in a pregnancy and birth. A second pregnancy was achieved following implantation of two cryopreserved embryos (one blastocyst and one morula). In conclusion, strontium treatment was found to be an effective method for artificial oocyte activation in a case with a low fertilization rate after ICSI.

No abstract

It has been reported that a sperm factor (SF) found in spermatozoa plays a critical role in fertilization. However, particulars of the oocyte-activating and Ca 2+ oscillation (Ca-Os)-inducing abilities of this SF remain unknown. We examined these abilities of spermatids in mouse, hamster and human by a mouse test (injection of spermatids into mouse oocytes). In mice, the round spermatids (ROS), elongated spermatids (ELS) and spermatozoa activated 0%, 93% and 92% of the oocytes, respectively. ROS injection resulted in no Ca-Os (type C). ELS induced a normal oscillation (type A) at 0% and an abnormal oscillation (type B) at 94%. Mouse spermatozoa induced type A Ca-Os at 90%. For mice, oocyte-activating and Ca 2+ oscillation-inducing ability arose in different phases of spermiogenesis. We also observed this differential timing for hamster spermatids. Hamster ROS activated 74% of oocyte (ELS: 90%, sperm: 86%). Human ROS activated 64% of oocytes (sperm: 100%), but only 35% of the oocytes showed type A Ca-Os. These results indicate that oocyte activation generally occurs between the ROS and ELS phases, although these phases differ among species. They also indicate that oocyte activation is not necessarily accompanied by Ca-Os. These findings suggest the existence of different thresholds at which the SF induces oocyte activation and Ca 2+ oscillation, or of different factors that induce oocyte activation and Ca-Os. We found SF to be clinically impaired in 0.9% of ICSI patients. A combination of artificial oocyte activation and ICSI proved effective with such patients.

Corrosion tests have been carried out in a simulated solution under heat transfer condition, in order to investigate the influence of boiling and NOx gas injection on the corrosion of austenitic stainless steels for the dissolvers of FBR fuel reprocessing plants.A simulated solution consisted of 4N nitric acid containing several non-radioactive ions. A specially designed heat transfer test cell could provide the precise control of heat flux. The test results are as follows:(1) Corrosion rates of both base metals and weld metals increased with heat flux under heat transfer condition. (2) Severer intergranular corrosion occurred on SW 310 weld metal.The maximum depth of the attack was larger than that of 310Nb base metal. (3) NO gas injection inhibits effectively the corrosion under non-boiling condition than boiling condition. The corrosion potential after stopping NO gas injection rapidly recovered under boiling condition. (4) Corrosion rates increased with the surface temperature of metal under both boiling and non-boiling conditions, but it should be noted that Arrhenius plot for boiling condition becomes higher than that for non-boiling condition in spite of the same surface temperature. As a result, it is demonstrated that boiling phenomenon is dominant factor rather than the surface temperature of metal in boiling condition.

There are cases in which the 1-day-old unfertilized oocytes after IVF, or in vitro matured oocytes obtained from denuded immature oocytes after ICSI, are used clinically. We investigated the morphological change of metaphase II spindle and chromosomal alignment in those oocytes. The spindles and chromosome were stained using an anti-α-tubulin antibody and Hoechst 33258 respectively. One-day-old oocytes displayed significant increases in abnormalities o f s p i n d l e s t r u c t u r e ( 4 0 . 4 % v s . 1 7 . 6 % ) a n d chromosomal alignment (40.4% vs. 29.4%). Oocytes matured in vitro from MI and PI oocytes displayed spindle morphological abnormalities at the rates of 41.7% and 36.0% respectively, and chromosomal alignment abnormality at the rates of 45.8% and 44.0% respectively. These results suggest that 1-day-old oocytes and in vitro matured oocytes obtained from denuded immature oocytes after ICSI might have lowered developmental potential. More than 50% of those oocytes were determined to be unsuitable for use as gametes.

Microinsemination is a revolutionary and promising technique for the treatment of severe male infertility, such as severe oligozoospermia, asthenozoospermia, and the case of unexplained unfertilization in which the conventional IVF is ineffective even if semen parameters are normal. Several different microinsemination techniques, such as zona opening [1][2][3], subzona sperm injection [4, 5], and intracytoplasmic sperm injection (ICSI) [6], have been introduced. ICSI is considered the most effective technique, because ICSI has the highest fertilization rate and can be performed with the smallest number of spermatozoa. In addition, this technique is effective for functional disorders, such as disorders of capacitation, acrosome reaction, and spermegg fusion. ICSI was first reported in 1992 [6], and for the above reasons became a powerful fertilization tool in only three or four years [7, 8].At first, ICSI was indicated for the treatment of severe infertility in which the probability of pregnancy was nonexistent or very law. Its indications were then expanded to include azoospermia, and it has been fairly effective [9][10][11], but in such cases chromosomal and genetic abnormalities may be passed on to children [12][13][14]. In addition, it has been clarified that ICSI is not effective in some cases, such as necrozoospermia [15], in which there are no viable spermatozoa; immotile spermatozoa [16], in which viable spermatozoa cannot always be picked up; cases in which spermatozoa have the disorder of oocyte activation factor; and azoospermia, in which mature spermatozoa cannot be found in the testes. The present paper concerns issues that must be considered in the performance of ICSI, as well as limitations to the effectiveness of ICSI. -ReviewNecrozoospermiaIn necrozoospermia, every spermatozoa on in semen is found to be dead when analyzed by vital staining (eosin stain [17], FertiLight stain (Molecular Probes, Eugene, OR) [18]). Sperm-injected oocytes are less likely to develop when injected with dead spermatozoa than with motile spermatozoa. The rate of fertilization for ICSI ranges from 0 to 11% [15]. Since 1992, 659 patients have been treated for infertility, a total of 1,317 treatment cycles at our hospital, and there had been six treatment cycles for necrozoospermia (3 patients). Among these cases, the rate of fertilization was 33.3% (5/15 oocytes), but there were no pregnancies. Since the fertilization rate was very low, dead (nonviable) spermatozoa may reduce the oocyte activating factor or have fragmented nuclear DNA or have chromosome disintegration [19]. Even when the sperm factor is injured and nuclear DNA is damaged, fertilization is possible with ICSI, but we cannot get well developed embryos from these spermatozoa, so that there is no hope of pregnancy. In humans, the development of fertilized oocytes to 4-cell stage embryos is controlled by the maternal genes rather than the paternal ones [20], so that fertilized oocytes can develop to this stage regardless of the state of the paternal DNA. The res...