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Y Kamiguchi

Publications and source records attributed to Y Kamiguchi.

32 records · Page 2Linked to original sources
PubMed1992

A freezing and thawing method of hamster oocytes designed for both the penetration test and chromosome assay of human spermatozoa.

Superovulated hamster oocytes were cryopreserved and thawed according to our carefully designed procedures. More than 90% (92 +/- 4%) of oocytes survived freezing and thawing. They were proven to be well conserved, showing excellent performance comparable to freshly ovulated oocytes in the human sperm penetration test (proportion of penetrated ova: 94.7% vs. 93.6%) and human sperm chromosome analysis (proportion of metaphasic ova: 81.8% vs. 83.6%). There was no statistically significant difference in the incidences of sperm chromosome aberrations between assays using fresh and frozen-thawed oocytes. In addition, there was no statistically significant increase of aberrations in female pronuclear (hamster) chromosomes. This freezing-thawing method was found to be reliable, yielding viable hamster oocytes of high quality.

Aneuploidy↗
PubMed1991

Micronucleus test in 2-cell embryos as a simple assay system for human sperm chromosome aberrations.

A micronucleus test method to assess radiation-induced chromosomal damage in human spermatozoa is described, and its efficiency examined by comparison with that of sperm chromosome analysis. Human spermatozoa were exposed in vitro to 1.11 and 2.13 Gy of 137Cs gamma-rays at a dose rate of 1.36 Gy/min. After interspecific in vitro fertilization of irradiated spermatozoa with zona-free hamster oocytes, a total of 193 monospermic eggs were examined with the micronucleus test at the 2-cell stage, and a total of 304 male pronuclear chromosome plates were analyzed according to our established method. The incidence of 2-cell embryos with micronuclei coincided well with the incidence of spermatozoa with chromosomal breaks and fragments (51.6% vs. 50.3% in the 1.11-Gy group and 82.7% vs. 79.3% in the 2.13-Gy group). A similar correlation was also found between the number of micronuclei per embryo and the number of breaks and fragments per spermatozoon (0.85 vs. 0.88 and 1.50 vs. 1.45 in the 2 dose groups, respectively). These results indicate that our micronucleus test is useful as a simple and rapid method for assessing the clastogenic effects of various environmental mutagens on human sperm chromosomes.

Animals↗
PubMed1990

Dose-response relationship for the induction of structural chromosome aberrations in human spermatozoa after in vitro exposure to tritium beta-rays.

The effects of tritium (HTO) beta-rays on human sperm chromosomes were studied using our interspecific in vitro fertilization system between human spermatozoa and zona-free hamster oocytes. Semen samples were treated with media containing 1.53-24.3 mCi/ml HTO for about 80 min. 1290 spermatozoa from the controls and 1842 spermatozoa from the irradiated groups were karyotyped. The incidence of spermatozoa with structural chromosome aberrations increased linearly with increasing dosage. Breakage-type aberrations occurred far more frequently than exchange-type. Chromosome-type aberrations appeared far more frequently than chromatid-type. All of these types of aberrations showed linear dose-dependent increases. The RBE values of HTO beta-rays relative to X-rays were calculated for the above-mentioned 5 indices, respectively. Their RBE values ranged from 1.89 to 3.00 when the absorbed dose was estimated to be the minimum, whereas the values ranged between 1.04 and 1.65 when the absorbed dose was estimated to be the maximum.

Beta Particles↗
PubMed1990

Types of structural chromosome aberrations and their incidences in human spermatozoa X-irradiated in vitro.

We studied the effects of in vitro X-irradiation on human sperm chromosomes, using our interspecific in vitro fertilization system between human spermatozoa and zona-free hamster oocytes. 28 semen samples from 5 healthy men were exposed to 0.23, 0.45, 0.91 and 1.82 Gy of X-rays. Totals of 2098 and 2862 spermatozoa were karyotyped in the control and the irradiated groups, respectively. The incidence of spermatozoa with X-ray-induced structural chromosome aberrations (Y) increased linearly with increasing dosage (D), being best expressed by the equation, Y = 0.08 + 34.52 D. The incidence of breakage-type aberrations was more than 9 times higher than that of exchange-type aberrations. Both of them showed linear dose-dependent increases, which were expressed by the regression lines, Y = -0.014 + 0.478 D and Y = -0.010 + 0.057 D, respectively. The incidence of chromosome-type aberrations was about 6 times higher than that of chromatid-type aberrations. Their dose-dependent increases were expressed by the regression lines, Y = -0.015 + 0.462 D and Y = -0.006 + 0.079 D, respectively. These results are discussed in relation to the previous data obtained with gamma-rays. The repair mechanism of X-ray-induced sperm DNA lesions is also discussed.

Animals↗
PubMed1990

A method for chromosome analysis of ram spermatozoa using zona-free hamster oocytes.

A method for displaying ram spermatozoan chromosomes using the interspecific zona-free hamster oocyte penetration was described to distinguish X- and Y-bearing spermatozoa. Semen samples from four rams were frozen and stored in liquid nitrogen. After thawing the samples, motile spermatozoa were collected by the swim-up method and treated with ionophore A23187 for the purpose of facilitating their capacitation. Slides were prepared by the gradual fixation-air dry method. The rates of oocyte penetration, first cleavage metaphase, and the number of ova that were karyotyped successfully were 67.9, 60.8 and 40.6%, respectively. The overall success rate (number of spermatozoa karyotyped/number of oocytes used for insemination) was 47.9%. A total of 1009 spermatozoa were analyzed, and the ratio of X- and Y-bearing spermatozoa was 508:501.

Journal Article↗
PubMed1986

A quantitative study of synaptic ribbons in pinealocytes of adult Chinese hamsters (Cricetulus griseus) under different photoperiodic conditions.

Synaptic ribbons (SR) in pinealocytes of adult (120-130 day-old) male Chinese hamsters (Cricetulus griseus) were classified into types 1, 2 and 3; these have a central dense structure showing rod-like, various and ring-like profiles, respectively. The central structure of the type-2 SR usually appeared as round, oval or comma-like bodies, and occasionally as plates showing various profiles or club-shaped bodies. The quantity of each type of SR, expressed as the SR index, was determined over a 24-h period under a light/dark regime (LD) 12:12 or LD 14:10. On comparing the results obtained from adults with previously published data from young (60-70-days-old) animals under LD 12:12, it was found that, in both young and adult animals, the type-1 and type-3 SR indices exhibited different 24-h variations, whereas the type-2 SR index remained constant over a 24-h period. In addition, the indices of the type-2 SR, but not those of the other SR types, were found to be significantly larger in adult than in young animals. In adult animals, the effects of the photoperiod were different between the three types of SR. A nocturnal increase in the type-1 SR index was observed under both LD 12:12 and LD 14:10, its time course being different for each of these photoperiods. Under LD 14:10, the type-2 SR index showed a significant 24-h rhythm with larger values during the dark period; this was not observed under LD 12:12. The type-3 SR index was almost the same under LD 12:12 and LD 14:10.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1986

An improved, efficient method for analyzing human sperm chromosomes using zona-free hamster ova.

We have developed an improved method for analyzing human sperm chromosome, using zona-free hamster ova. Our main improvements of methodology are as follows: (1) Fertilization rate of hamster oocytes by human spermatozoa was markedly raised by successive treatments of the spermatozoa with 5-15 microM ionophore A23187 solutions and a capacitation medium (BWW medium) containing 3.5% HSA. The HSA most effective in inducing capacitation was selected from several kinds of HSA products commercially available. (2) Monospermic fertilization was ensured by inseminating oocytes with highly capacitated spermatozoa at a low concentration for a short time. (3) TC medium 199 was used for postinsemination culture of the eggs. (4) A medium containing podophyllotoxin and vinblastine (0.04 micrograms/ml each) was used to block karyogamy and first-cleavage spindle formation. (5) Chromosome slides were prepared with our gradual fixation-air-dry method instead of Tarkowski's method. Ninety-two to 177 spermatozoa corresponding in number to 43%-79% (mean: 62%) of the inseminated oocytes were successfully karyotyped in each experiment. In spite of above-mentioned quantitative improvements, quality of Q-banding was not necessarily satisfactory in our slides. Improvement of banding technique is an important problem to be solved in our method. Spontaneous incidence of chromosome aberrations was studied in a total of 1,091 spermatozoa obtained from nine semen samples from four donors. Incidences of aneuploidy and structural anomaly were 0.9% (hyperhaploidy, 0.45%; hypohaploidy, 0.45%) and 13.0%, respectively. Structural aberrations included breaks (45.1%), fragments (32.4%), exchanges (21.8%), and deletions (0.7%). Ratio of X-sperm to Y-sperm was 53% to 47%. These results were discussed in comparison with those reported previously.

Animals↗
PubMed1985

Maturation of spermatozoa in the epididymis of the Chinese hamster.

Chinese hamster spermatozoa gain their ability to move when they descend from the testis to the distal part of the caput epididymis, but it is not until they enter the corpus epididymis that they become capable of fertilizing eggs. The maturation of the spermatozoa proceeds as they further descend the tract and perhaps continues even in the vas deferens. During transit between the distal caput and proximal cauda epididymides, small membrane-limited vesicles (and tubules) appear on the plasma membrane over the acrosomes of the spermatozoa. The number of vesicles appearing on the sperm brane reaches a maximum when the spermatozoa are in the proximal cauda epididymis. It declines sharply in the distal cauda epididymis. Spermatozoa in the vas deferens are free of the vesicles. The origin, chemical nature, and functional role of the vesicles that appear on the sperm surface during epididymal transit must be the subject of further investigation.

Animals↗