ABSTRACT
To enhance the likelihood of cavitation, pregnant mice were subjected to hyperbaric conditions and quickly returned to atmospheric pressure. Following this treatment, they were exposed to spatial average, pulse average intensities of 100 W/cm2 (2.2-MHz, 20-microseconds pulses with a duty cycle of 1/1000 or a temporal average spatial average intensity of 0.1 W/cm2). Fetal weights, deaths and malformations were scored. No statistically significant effects were observed in the offspring.
Subject(s)
Fetus/physiology , Pressure , Ultrasonics , Animals , Body Weight , Embryonic and Fetal Development/physiology , Female , Fetal Death/etiology , Fetal Resorption/etiology , Litter Size , Logistic Models , Mice , Mice, Inbred C3H , Mice, Inbred Strains , Pregnancy , Prenatal Exposure Delayed Effects , Pressure/adverse effects , Probability , Time Factors , Ultrasonics/adverse effects , Ultrasonography, PrenatalABSTRACT
It has been suggested that fetal weight reduction by ultrasound exposure is linearly related to the dose parameter I2t, where I is the intensity and t the exposure time. A direct test of the concept was conducted using CF-1 mice. No effect on fetal weight was found at values of the dose parameter large enough to produce measurable heating in the fetal and maternal tissues.
Subject(s)
Fetus/anatomy & histology , Ultrasonography/adverse effects , Weight Loss , Animals , Female , Mice , PregnancyABSTRACT
Ultrasonographic assessment of ovarian follicular maturity was reportedly associated with atypically early ovulation in women; related studies reported reduced litter sizes in rats. To confirm these findings, mice which were midway between ovulatory gonadotropin (LH or human chorionic gonadotropin) stimulation and ovulation, were sham- or ultrasound-treated periovarially for 5 min. Exposure was at a spatial average, temporal maximum intensity of 60 W/cm2. Carrier frequency in the pulse was 2.2 MHz, pulse length was 10 microseconds, and pulse repetition frequency was 200 Hz. Spatial average, temporal average intensity was 0.12 W/cm2. At autopsy, ultrasound- and sham-treated groups responded similarly in proportions ovulating and in mean ova ovulated. Combined experiments had a 97% chance of detecting a significant (greater than 1 h) advance in ovulation time, had it occurred. Thus, our adequately sensitive mammalian ovulatory tests revealed no association of ultrasound with decrease in ovum number or acceleration in ovulation time (as reported in humans).
Subject(s)
Ovulation , Ultrasonography/adverse effects , Animals , Chorionic Gonadotropin/administration & dosage , Female , Gonadotropins, Equine/administration & dosage , Mice , Mice, Inbred BALB C , Ovulation Induction , Ovum , Time FactorsABSTRACT
Our replicate of a study by Takabayashi et al. (1981) Effects of pulse-wave ultrasonic irradiation on mouse embryo. Cho-Onpa Igaku (Supersonic Medicine) 8, 286-288 failed to show any effects of exposure in utero of mice to spatial average, temporal maximum intensities of 60 W/cm2. Fetuses were exposed at 8 days post fertilization and assessed at 18 days for fetal weight, resorptions, premature deaths, and malformations. Carrier frequency in the pulse was 2 MHz. Pulse lengths of 10 microseconds and pulse repetition frequencies of 1000 and 200 Hz yielded spatial average, temporal average intensities of 0.6 and 0.1 W/cm2. Total exposure time was 5 min. Our results provide no basis to conclude that conditions relevant to human fetal monitoring will cause developmental, externally visible anomalies in mice exposed as 8-day fetuses.
Subject(s)
Congenital Abnormalities/etiology , Ultrasonics/adverse effects , Animals , Female , Fetal Death/etiology , Mice , Mice, Inbred BALB C , PregnancyABSTRACT
Reproductive effects of the environmental pollutant methylmercuric chloride administered as a single dose per os during pregnancy were studied both in treated mice (G0 generation) and in their prenatally exposed offspring (G1). Treatment at 9.5 days postfertilization caused no observed effects at doses as high as 12-18 mg Hg+/kg. In contrast, treatment at 12.5 and 15.5 days produced toxicity; results were similar and were combined for analysis. Among G0 mice, the percentage capable of delivering one or more viable pups showed an estimated threshold level response at 8.0 mg/kg. The percentage of G1 pups that were viable at 1 day post partum was significantly dose-related, with an approximate threshold exposure level of 4.3 mg/kg. Among the surviving G1 offspring, body weight in adulthood (8 months) showed a statistically significant reduction that was also dose-related. Fertility testing of G1 offspring revealed no treatment effects on mating behavior judged by time interval between pairing and parturition. However, there was a trend (statistically nonsignificant) toward a dose effect on sizes of females' litters. Sterility (inability to produce offspring) did not occur either among G1 males at 4 months of age (N = 30; dose 8-12 mg/kg) or among females up to the advanced reproductive age of 14 months (N = 29; dose 5.3-12 mg/kg). We conclude that mice exposed prenatally to methylmercuric chloride revealed no greater susceptibility to sterility than to perinatal mortality.
Subject(s)
Growth/drug effects , Methylmercury Compounds/toxicity , Prenatal Exposure Delayed Effects , Reproduction/drug effects , Animals , Body Weight/drug effects , Female , Fertility/drug effects , Mice , Mice, Inbred BALB C , PregnancyABSTRACT
Recent developments suggest that transient cavitation must be considered in assessing the safety of diagnostic uses of ultrasound. An analysis of the literature on exposure of the fetus to pulsed ultrasound reveals no direct evidence that diagnostic ultrasound produces any effect on the fetus.
Subject(s)
Fetus , Ultrasonics/adverse effects , Animals , Chickens , Humans , Mice , Rats , UltrasonographyABSTRACT
Numerical chromosomal aberrations (aneuploidy) are a major factor in pregnancy wastage, birth defects, and mental retardation. Consequently, effective cytogenetic procedures in mammalian gamates are required for studying mechanisms and causes of chromosomal nondisjunction. Our aims were to determine for oocytes from superovulating prepubertal mice: (1) the yield of chromosomally scorable ova, following application of a double fixation procedure: (2) the background level of aneuploidy, and (3) the sensitivity to induction of aneuploidy (by methotrexate). Superovulation was induced in C129F1 hybrid mice, 22-24 days old, with pregnant mare serum and human chorionic gonadotropin (HCG). Diurnal photoperiodicity and injections were scheduled to assure HCG-induced ovulation of known timing. Methotrexate (200 mg/kg) was given at 3 hr and ova were recovered at 15 hr after HCG. We describe the adaptation of a double fixation procedure to mouse oocytes. Methotrexate led to significantly increased hypoploidy (2 1/2-fold) but not to the hyperploidy reported by others for adult mice. There was a high yield of ova with exactly countable chromosomes (average of 9.5 ova per mouse). Concomitantly, the background level of aneuploidy was very low (0/465 scorable ova were hyperploid). Given the additional advantages of economy and convenience, the superovulating 3-week-old mouse could be an effective source of ova for testing environmental agents for their aneuploidy-inducing potential; however, further studies are needed to establish the degree to which such ova are susceptible to aneuploidy induction.