摘要:

AbstractThe developmental origin of arsenate‐induced renal agenesis was investigated. Pregnant Wistar rats were each injected once ip with 45 mg/kg sodium arsenate at day 10 (sperm day = day 0). Pregnancy was terminated at various times following injection and the embryos recovered and serially sectioned. Renal agenesis resulted when the mesonephric duct failed to give rise to a ureteric bud with subsequent failure of induction of the metanephric blastema. The underlying defect was retardation in growth of the mesonephric duct, first observed 48 hours after arsenate injection. A shortened mesonephric duct also resulted in a failure of the mesonephros to attain normal size and in the male resulted in absence of the ductus deferens, seminal vesicle and a variable portion of the epididymis. Due to the intimate association of the mesonephric and growing paramesonephric ducts, a shortened mesonephric duct resulted in a shortened paramesonephric duct with resultant lack of a uterine hor

ISSN:0040-3709    

DOI:10.1002/tera.1420160303

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractOne hundred fifty embryos with holoprosencephaly were found among the total of 36,380 conceptuses obtained through induced abortion in the period from 1962 to 1974, giving an overall incidence of 0.4%. The occurrence was largely at random through time, and no “epidemic” was noted in particular years or months, but there appeared more cases derived from conceptions in winter than in summer months. The mean maternal age did not differ significantly from that of the general embryonic population, indicating that, although none of our cases were karyotyped, chromosome aberrations such as trisomies 13 and 18 that are closely associated with maternal age may not constitute a major part as causes of holoprosencephaly in human embryos. Maternal age did not differ by the presence or absence of associated external anomalies. No association was found with paternal age, parental consanguinity nor with maternal medical history, including irregularity of menstrual cycles, and smoking and drinking habits. There was an indication that the mothers were prone to have repeated miscarriages, supporting the view that some kind of maternal predisposition is responsible for the causation of holoprosencephaly. Argument was made that, apart from various chromosome aberrations well documented as causes of this malformation, polygenic mechanism probably accounts for the majority of the cases with normal karyot

ISSN:0040-3709    

DOI:10.1002/tera.1420160304

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractThe effect of intravenously administered inorganic lead on periimplantation period of embryonic development in the mouse was investigated with light microscopy. Three developmental stages were studied: the attachment of the blastocyst, the invasion of the trophoblast and the formation of the primitive streak. All three stages were affected, but the stage of invasion was found to be the most susceptible to lead as determined by decrease in frequency of animals with normal embryos.

ISSN:0040-3709    

DOI:10.1002/tera.1420160305

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractThe incidence of cleft lip and/or cleft palate was examined for the 1952‐71 period for the Province of British Columbia. Although there were some fluctuations, some of which were significant, there was no general trend which indicated that the rates were either increasing or decreasing. These rates are important for a background calculation when investigating new environmental teratogens. The total rate of 1.97 per 1,000 live births is comparable with other Caucasian populations where there is good ascertainment and adequate follow‐up period. This study also confirmed the previously reported high rate for North American Indians in British Columbia (3.74 per 1,000 live births) and established rates for the Japanese (3.36 per 1,000 live births) and Chinese (1.76 per 1,000 live births) of British Columbia. Since these three sub‐populations are relatively small in relation to the total population, they do not influence the overall total rate to any great e

ISSN:0040-3709    

DOI:10.1002/tera.1420160306

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractRhesus monkey fetuses were inoculated with Venezuelan Equine Encephalitis (VEE) vaccine virus by the direct intracerebral route at approximately 100 days gestation to determine possible teratogenicity of the virus. Congenital micrencephaly, hydrocephalus and cataracts were found in all animals and porencephaly in 67% of the cases. The virus replicated in the brain and other organs of the fetus. VEE vaccine virus is teratogenic for non‐human primates and must be considered a potential teratogen of ma

ISSN:0040-3709    

DOI:10.1002/tera.1420160307

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractPregnant rabbits were injected ip with 5 mg/kg 6‐ANA at day 10, 11, 12 or 12.5 respectively of gestation. Embryos removed at day 13 of gestation had reduced DNA and RNA concentrations. The differences (DNA: 14%; RNA: 22.4%) were significant in the group treated on the twelfth day. Some possible mechanisms are discusse

ISSN:0040-3709    

DOI:10.1002/tera.1420160308

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractCleft palate induction by 6‐aminonicotinamide (6‐AN) was examined in the A/J and C57BL/6J strains of mice to determine the nature of the strain difference in frequency of cleft‐palate response. Probit analysis of the cleft‐palate response to dose of different genotypes revealed a family of linear and parallel dose‐response curves. The genotypes differ only in dosage tolerance (log ED50) to 6‐AN that is required for the cleft‐palate response. No evidence for a maternal cytoplasmic effect on 6‐AN‐induced cleft palate was found under the conditions of the present study. When the difference in dosage tolerance to 6‐AN between A/J and C57BL/6J was examined with a single dose and measured by differences in frequency of induced cleft palate on a probit scale, there was some departure from genetic additivity. There was an indication of dominance deviation of the F1embryos in the direction of C57BL/6J. A 3‐locus, epistatic model is proposed to account for the difference in embryonic tolerance to 6‐AN‐induced cleft palate. There was a suggestion of association

ISSN:0040-3709    

DOI:10.1002/tera.1420160309

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractThe pregnant rhesus monkey's(Macaca mulatta)potential as a model for understanding the dynamics of alpha‐fetoprotein (AFP) metabolism in human pregnancy was evaluated. AFP levels in maternal and fetal serum and amniotic fluid were determined by radioimmunoassay. Significant correlations were found between decreasing maternal serum, fetal serum and amniotic fluid AFP concentrations and increasing gestational age. However, these data are not consistent with the AFP changes reported in human pregnancy. It appears that this animal has limited applicability as a model in this aspect of human pregnanc

ISSN:0040-3709    

DOI:10.1002/tera.1420160310

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractExposure of developing eggs of the killifish,Fundulus heteroclitus, to 0.03 or 0.04 mg/1 of methylmercuric chloride resulted in a variety of abnormalities. Percentage of axis formation was reduced somewhat, and many embryos developed cyclopia or intermediate conditions leading to cyclopia, reflecting interference with induction of the forebrain. Defects in the cardiovascular system also appeared in the form of failure of the heart to differentiate properly into chambers. The heart was a thin, feebly beating tube, incapable of causing the blood to circulate. Other tissues, however, continued developing fairly normally, and embryos showed spontaneous movement comparable to controls. Embryos with severe cardiovascular or optic defects did not hatch. Upon hatching, some embryos which had previously appeared normal, were found to have skeletal malformations in the form of vertebral bends or the inability to uncurl from the position which they had had while still inside the chorion. Exposure to the toxicant for shorter periods of time (6, 12, or 24 hours) reduced the incidence of abnormalities. The second day of development was found to be the most sensitive period.

ISSN:0040-3709    

DOI:10.1002/tera.1420160311

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractThe uterine artery of one horn of 13 rats was ligated on day 18 of gestation; the remaining horn was used as a control. The effect, four days later, on blood flow to the reproductive tract, was measured with radioactive microspheres and compared to the effect on fetal and placental weights. Fetal survival in the ligated horns, 41%, was significantly lower (P<0.05) than that in the control horns, 98%. Fetal and placental weights of the survivors in the ligated horns, 3.159 ± 0.133 g (SE) and 450 ± 18 mg respectively, were similarly lower than those in the control horns, 3.814 ± 0.111 g and 529 ± 27 mg respectively. Maternal placental blood flow closely reflected the weight of tissue being supplied and was similar in the ligated and control horns, 129 ± 21 and 130 ± 18 ml.min−1. 100g−1, respectively. Myometrial blood flow was again similar in the ligated and control horns, 34 ± 5 and 37 ± 4 ml.min−1. 100 g−1, respectively, and in the ovarian, middle and cervical sections of each horn. These results are compatible with the view that ligation causes only a temporary reduction in uterine blood flow which permanently checks placental and fetal, or placental thus fetal, growth. Blood flow then returns to normal levels compatible with the reduced weights of tissues

ISSN:0040-3709    

DOI:10.1002/tera.1420160312

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY