bluuebunny/crossref_metadata_2025 huggingface dataset:
Migration and proliferation of primordial germ cells in the rat
Authors: Kemper C. H. , Peters P. W. J.
Published: June 2005

Information about early primordial germ cell (PGC) formation and migration in rats is lacking. In utero developed and in vitro cultivated whole rat embryos were studied on days 10‐‐13 postcoitum (p.c.). The development of the PGCs was investigated in serial sections stained for alkaline phosphatase activity. On postcoital day 10, PGCs were found in the invaginating visceral yolk sac endoderm and at the base of the allantois. At day 11 p.c. PGCs were mostly found in the ventral and lateral gut wall or in the mesenchyme between the gut and the future genital ridges. At day 12 p.c. most of the PGCs (94%) could be localised in the mesenchyme or in the future genital ridges. On postcoital day 13 almost all PGCs had reached the now‐well‐developed genital ridges. Quantitative measurements showed an increase in the number of PGCs from 84 at day 10 p.c. up to 2,768 at day 13 p.c. Only slight differences were found between in vivo and in vitro embryos with respect to the number of PGCs and their developmental pattern. The in vitro culture of whole rat embryos enables the discrimination between the effects of indirect (maternal) and direct action of PGC‐toxic agents.
Ethanol treatment inhibits mesoderm cell spreading in the gastrulating chick embryo
Authors: Sanders E. J. , Cheung E. , Mahmud E.
Published: June 2005

Gastrulating chick embryos in culture were treated with ethanol solutions, following which the mesoderm cells migrating from the primitive streak were examined by scanning electron microscopy. Morphometric analysis of cell shape showed that mesoderm cells from treated embryos were significantly more rounded and therefore less well spread than controls, and showed fewer filopodial contacts with the overlying basement membrane. This result was only obtainable for cells leading the migration from the primitive streak, since the following cells in the mesodermal mass apparently did not show this difference. The ethanol concentration required to obtain a reliable effect was 5%, while lower concentrations produced highly variable results. The mesoderm cells were also examined for their in vitro responsiveness to ethanol by investigating their adhesiveness and cytoskeleton. No effect was observed on cell‐glass adhesion as judged by interference reflection microscopy using up to 1% ethanol. This concentration did, however, disrupt the actin cytoskeleton of cultured cells when stained with NBD‐phallacidin, but lower concentrations were ineffective. It is concluded that ethanol treatment of cultured embryos has a significant effect on the substratum relationships of some migrating mesoderm cells.
Mercury 203 distribution in pregnant and nonpregnant rats following systemic infusions with thiol‐containing amino acids
Authors: Aschner Michael , Clarkson Thomas W.
Published: June 2005

Near‐term pregnant (gestational day 17) and nonpregnant Long‐Evans female rats were continuously infused into the external jugular vein with 0.1 mmole/hour L‐cysteine, 0.1 mmole/hour L‐leucine, or saline. At 24, 48, and 72 hours, 50 μmole/hour [203Hg]‐MeHgCl was administered over 1 hour. Total 203Hg body burden, brain, kidney, liver, and blood 203Hg concentrations were determined at 96 hours by gamma scintillation spectrometry. Despite significantly greater 203Hg whole body retention in the pregnant animals 203Hg concentrations in blood, brain, kidney, and liver were higher in nonpregnant rats. In addition, brain 203Hg concentrations in both pregnant and virgin rats were significantly higher in L‐cysteine‐treated rats compared with controls. These results suggest that the fetus may act as a “sink” for MeHg, thus decreasing 203Hg concentrations in maternal blood, brain, kidney, and liver. Furthermore, the data indicate that brain uptake of methylmercury in both pregnant and nonpregnant rats is enhanced by chronic L‐cysteine infusion, lending support to the hypothesis that methylmercury in the rat may be translocated across the blood‐brain barrier by the neutral amino acid carrier transport system.
Effects of differential alcohol dehydrogenase activity on the developmental toxicity of ethanol in Drosophila melanogaster
Authors: Ranganathan Sulabha , Davis D. Gale , Leeper James D. , Hood Ronald D.
Published: June 2005

The role of alcohol dehydrogenase (ADH) activity in ethanol toxicity was investigated in Drosophila melanogaster. Flies from three congenic Adh strains (high, medium, and low ADH activity) were allowed to deposit eggs on medium containing 0, 4, or 8% ethanol. The resulting larvae were allowed to complete their development in the medium, and emerging flies were examined for defects. Flies with high ADH activity had malformation incidences of 0.8, 2.4, and 5.2% at 0, 4, and 8% ethanol, respectively. The comparable incidences for the low ADH strain were 1.0, 4.1, and 8.4%, while those for the medium ADH strain were intermediate in value. These results indicate that ethanol teratogenesis may be inversely related to ADH activity. When larvae were treated with ethanol for different lengths of time during development, the incidence of defects in flies from the high ADH strain was 3.9% when exposure started at the first instar and 3.09% when exposure started at the third instar. Results of the same exposures for the intermediate ADH strain were 5.2 and 3.4%, respectively, while those for the low ADH strain were 6.9 and 5.5%, respectively. Thus, length of ethanol exposure was directly related to the increased incidence of malformations in all tested Drosophila strains. For all tested strains, defect incidences appeared to be doserelated as well, regardless of length of exposure. ADH in Drosophila has a dual function and thus can catalyze oxidation of both ethanol and its toxic metabolite, acetaldehyde. This suggests that ethanol is the proximate teratogen in Drosophila.
Zinc amelioration of cadmium toxicity on preimplantation mouse zygotes in vitro
Authors: Yu H. S. , Chan S. T. H.
Published: June 2005

Zinc, at a concentration of 5 or 10 μg/ml medium, has been shown to protect mouse preembryos in vitro from the toxicity of cadmium at a concentration of 5 μg/ml medium after a simultaneous treatment of the ions from four‐cell to morula or from morula to blastocyst for 24 hours. Such an amelioration indicates that cadmium toxicity is a result of the unique property of the cadmium ion and is not due to an alteration in the culture medium after the addition of an extra metallic ion. Zinc probably ameliorates cadmium treated mouse preembryo by competing with cadmium for uptake or some other metabolic processes. In view of the well‐documented competition between cadmium and zinc ions for binding sites in many other cell types, some macromolecules to which similar divalent metallic ions bind competitively may also exist in the mouse preembryo. This suggests that a protective mechanism dependent on the metal‐metal interactions begins to operate in the mouse preembryo at a very early stage of differentiation before implantation.
Light microscopic studies on the pathogenesis of exencephaly and cranioschisis induced in the rat after neural tube closure
Authors: Padmanabhan R.
Published: June 2005

Administration of a single dose of cyclophosphamide (20 mg/kg) to Charles Foster (CF) rats on day 12 of gestation (i.e., well after neural tube closure) results in exencephaly in almost 100% of living fetuses at term (Padmanabhan, '84). Following the same treatment, embryos/fetuses were collected at various intervals of time (from 8 hr to day 19 of gestation) and studied histologically. At 10 hr after treatment, the neuroepithelium (NE) of the brain vesicles and the neural crest‐derived ganglia exhibited pronounced cell death. By day 13, cell death appeared to be more intense and extensive in the NE; the mesenchyme (ME) was less proliferative and was loosely organized. In the following days, the NE presented vacuolizations which coalesced into cavities; these cavities were often bilaterally symmetrical, contained free neuroblasts and erythrocytes, and subsequently opened into the ventricles. The choroid plexus hypertrophied, the ventricles distended, and the NE gradually became very thin. The hypertrophied capillaries of the ME cleaved through the NE, thus delaminating an outer stratum. Subcutaneous blebs developed over the brain vesicles and communicated with the cavities in the brain. Thus the ventricles and the blebs came into direct communication. The ME dorsal and lateral to the brain was loose, and at no site was it organized into the skull primordium. By day 19, there were clear and multiple discontinuities in the walls of the brain. Initial cell death and vacuolization in the NE, inhibition of ME proliferation followed by hypertrophy of the choroid plexus, and possibly enhanced intraventricular pressure and hemorrhage and edema of the ME seem to underlie this process of reopening of the closed neural tube.
Development of rat embryos cultured in serum prepared from rats with streptozotocin‐induced diabetes
Authors: Rashbass P. , Ellington S. K. L.
Published: June 2005

The effects of 40, 50, and 60 mg/kg streptozotocin (SZ) on the body weights and the glucose concentration and the osmolarity of the serum of adult rats were determined. Serum prepared from these SZ‐dosed rats was used in embryo culture experiments to investigate effects of diabetic serum on rat embryos during organogenesis. The diabetic serum resulting from each of the tested doses of SZ was teratogenic to 9.5‐day rat explants (embryos and their membranes), causing a range of dysmorphic lesions including cranofacial defects, heart defects, and abnormalities of the branchial arches and the otic capsules.

Explants cultured in serum prepared from rats dosed with 60 mg/kg SZ also showed abnormal morphology of both the visceral yolk sac and the embryonic blood cells in the yolk sac capillaries.

The development of explants repeatedly transferred between control and diabetic serum indicated that the severity of the dysmorphic effect was dependent on the duration of exposure to diabetic serum. The alternation of sera did not in itself appear to be damaging to the embryos.

Explants cultured in control serum, control serum with its glucose concentration increased to that of the diabetic serum, or diabetic serum all took up the same amount of glucose from their culture medium; 30% of the embryos from the diabetic serum were abnormal compared to only 4% from the control serum and the control serum plus glucose.
Blood alcohol concentration and microencephaly: A dose‐response study in the neonatal rat
Authors: Bonthius Daniel J. , West James R.
Published: June 2005

The relationships among microencephaly, peak blood alcohol concentration (BAC), and dose of alcohol were examined in a rat model of third‐trimester fetal alcohol effects. Ethyl alcohol was administered to neonatal rats from postnatal day 4 to day 10 during the brain growth spurt via an artificial rearing technique. Groups of rats received one of nine doses of alcohol (0.0, 2.5, 3.3, 4.0, 4.5, 5.3, 6.6, 7.5, or 8.5 g/kg body weight) administered in 8 hours each day. BACs were determined on postnatal days 6 and 7 at times corresponding to peak and trough BACs, respectively. On postnatal day 10, brains were removed, and total brain weights, cerebellar weights and brainstem weights were measured. Pups receiving 4.0 g/kg/day or less had mean peak BACs below 150 mg/dl and did not exhibit significant microencephaly when compared with controls. Higher dosages further increased the peak BAC and produced significant microencephaly. While a dose of 4.5 g/kg/day was sufficient to decrease significantly both total brain weight and cerebellar weight, a minimum dose of 6.6 g/kg/day was required for significant restriction of brainstem weight. The dose of 7.5 g/kg/day yielded a mean peak BAC of 420 mg/dl and reduced total brain weight, cerebellar weight, and brainstem weight by 33%, 52%, and 22%, respectively, relative to controls. Exposure to 8.5 g/kg/day was uniformly lethal. Peak BAC and total brain weight were highly correlated (r = −.916). As peak BAC increased, total brain weight decreased linearly. Comparisons with previous studies indicate that condensing the daily dose of alcohol effectively reduced the threshold doses for microencephaly and lethality.
Caffeine and reduction of fetal ossification in the rat: Fact or artifact?
Authors: Muther Thomas F.
Published: June 2005

This study was done to determine the gestational period during which the rat fetus is susceptible to reduction of skeletal ossification by caffeine. Caffeine, 100 mg/kg/day by gavage, caused the greatest reduction in ossification, as assessed by staining with alizarin red S, in fetuses exposed between day 16 to 19 of gestation, less in those treated between day 7 to 19, and markedly less in those receiving it between day 7 to 16; a single dose on day 19 had very little effect. This indicates that the fetus is most susceptible late in pregnancy. Bones in early stages of mineralization on day 20 showed a greater reduction in staining than those in later stages. Thus, caffeine appears to lower the rate of ossification rather than reduce its final extent.

In the day 7 to 19 caffeine treatment group, but not in the day 16 to 19 group, maternal and fetal body weights were reduced, and 1.6% of the fetuses had aphalangia. The day 7 to 16 caffeine treatment reduced fetal body weight. This argues against an association between reduction in fetal weight and ossification. None of the treatments affected rates of resorption or litter size.

A novel and important observation made is that the different caffeine treatments affected the staining by alizarin of both claws and bones in a qualitatively and quantitatively similar manner. Since claws are devoid of osteoid, this observation questions the specificity of alizarin for the assessment of the state of fetal ossification and raises doubt as to the significance of the observed action of caffeine on ossification.
The developmental pathology of maternally derived Thp fetuses
Authors: Babiarz Bruce S. , Donovan Michael J. , Hathaway Helen J.
Published: June 2005

The Thair pin (Thp) mutation is a deletion of 5 centimorgans of chromosome 17 in the mouse. When the mutant chromosome is passed to the fetus through the female, the heterozygous fetuses (Thp/+) die in utero. If the chromosome is passed through the male, the heterozygotes are viable and display a short‐tailed phenotype. These maternally derived mutant embryos provide an excellent model system to study the effects of an incomplete female genome on development. The results reported here describe the findings of a pathological study of the affected fetuses from day 14 of development to birth. These observations indicate that the maternally derived Thp fetuses die in utero of congestive heart failure. The mutant fetuses displayed an enlarged heart, primarily the right side, and other cardiovascular abnormalities including ventricular septal defects, aortic stenosis, pulmonary artery dilation, and dilation of the venous circulatory system. The fetuses also displayed abnormal accumulation of extrafetal fluid in the visceral yolk sac and amion, as well as massive subcutaneous edema and ascites. The Thp fetuses were often pale and anemic, and they showed a decreased number of red blood cells per unit volume of blood and an increase in circulating nucleated red blood cells. Defects in the development of the labyrinthine and spongiotrophoblast regions of the placenta were also observed. The pathogenesis of the defects is discussed.
Importance of genetic predisposition and maternal environment for the occurrence of congenital malformations in offspring of diabetic rats
Authors: Eriksson Ulf J.
Published: June 2005

Previous experimental studies have implicated a genetic component in the induction of malformations in the offspring of diabetic rats. We have compared the outcome of diabetic pregnancy in two outbred (sub)strains of Sprague‐Dawley rats (with low incidence [H] and high incidence [U] of skeletal malformations in the offspring) and hybrids between them. The fetuses of diabetic H mothers had no skeletal malformations and the lowest frequency of resorptions (8–9%), regardless of embryo type (H/H or H/U). When the diabetic mother was U or from the hybrid strain (H/U) and the offspring were of the mixed H/U type, we found increased resorption (16–21%) and skeletal malformation (3–5%) rates. If instead the embryos contained a major U genome [either U/U or U/(H/U)], further increased resorptions (23–30%) and skeletal malformations (17–19%) resulted. The H/H and U/U embryonic susceptibility to defined teratogens (3–6 mg/ml D‐glucose, 4–8 mM B‐hydroxybutyrate) were compared in whole embryo culture and found to be similar, suggesting that the malformations occurring in vivo may have a different etiology than those found in vitro. In the rat model studied, diabetes in the mother appears to cause a disturbance of early stages of embryogenesis in genetically predisposed embryos. This early disturbance results in skeletal malformations and seems to require inducing factor(s) in addition to increased levels of D‐glucose and B‐hydroxybutyrate. The findings are in concert with the notion of a mixed genetic‐environmental etiology of malformations in (diabetic) pregnancy.
The position effect in mice on day 19
Authors: Louton Tom , v. Domarus Helmut , Hartmann Petra
Published: June 2005

This investigation on the position effect in mice on day 19 was based on a total of 610 fetuses from 51 litters of NMRI mice. The relative position of each fetus was determined by setting the distance from the center of each placenta to the cervix in relation to the total length of the uterine horn. After cessation of shrinkage due to fixation, the umbilical‐cord and remaining membranes were removed and the fetuses were weighed to the nearest 0.1 mg. The variance for the weighing procedures was estimated at 4 mg. The fetuses were uniformly distributed on a segment beginning about 7% beyond the cervical end and proceeding to about 10% short of the ovarian end. A mixed model analysis of variance was applied to estimate the position effect: the deviation of the individual weights from the mean for each uterine horn were modeled as a second degree polynomial of the relative position. A position effect was found; the fetuses on the cervical end were lighter, those in the middle were roughly the same, and those of the ovarian end were heavier than the average.
Strain difference in galactokinase level and susceptibility to the teratogenic effect of dietary galactose in mice: I. Teratogenic and embryopathic effect
Authors: Shih Ling Yu , Kuerer Henry M. , Chen Tsui Hua , Desposito Franklin
Published: June 2005

Congenital cataracts have been noted to occur in infants when either the mother or the mother and infant have reduced activity of the enzymes galactokinase (GK) or galactose‐1‐phosphate uridyl transferase (GALT). Studies were undertaken to elucidate the possible genetic and dietary fetomaternal interactions leading to the presumptive galactose teratogenesis noted in two inbred strains of mice differing in GK activity. Pregnant A/J (high erythrocyte GK activity 134.18 ± 17.89 mU/gm Hb) and C57BL/6J (low erythrocyte GK activity 55.05 ± 11.39 mU/gm Hb) mice were treated with a diet containing either 25% or 50% galactose throughout gestation. A significantly higher percentage of C57BL offspring (92.3%) were observed to have lens opacities when their mothers were fed a high‐galactose diet, whereas no increase in lens pathology was observed in the offspring of similarly treated A/J mothers. Additionally, reciprocal matings were carried out so that all offspring were genetically equivalent in terms of GK activity. However, when the mother had low GK activity, a significant incidence of lens opacities was present in their offspring; this was not found when the mother had high GK activity. After weaning, no difference in the incidence of lens opacities was observed when the 25% galactose diet was introduced to the offspring of these reciprocal crosses, providing additional support for a maternal dietary influence on the development of lens opacities.
A mechanism of dimethylsulfoxide protection against the teratogenicity of secalonic acid D in mice
Authors: ElDeib Mohamad M. R. , Reddy C. S.
Published: June 2005

Dimethylsulfoxide (DMSO) is known to antagonize the teratogenic effects of secalonic acid D (SAD) in mice. To establish the optimum protective dose of DMSO, pregnant CD‐1 mice were treated, i.p., with 30 mg/kg of SAD in 5% (w/v) NaHCO3, containing 0, 10, 20, or 30% (v/v) DMSO on day 11 of gestation. Data indicate that at 10% and 20% levels, DMSO affords an apparent dose‐related protection against SAD‐induced cleft palate, whereas 30% DMSO enhanced fetal resorption with no reduction in the incidence of cleft palate. Ultraviolet spectra and TLC mobility indicated that DMSO at 20% did not directly interact with SAD. Distribution and elimination of 14C‐SAD was studied in fetal and maternal tissues from pregnant mice at 24 and 48 hr after exposure to 30 mg/kg of 14C‐SAD, i.p., in NaHCO3 (control) or in 20% DMSO. Compared with those not receiving DMSO, maternal exposure to DMSO: (1) significantly reduced (42–75%) radioactivity in fetal heads and bodies, placenta, and maternal tissues other than liver; (2) significantly increased (up to 222%) the radioactivity in maternal liver; and (3) significantly reduced (44–58%) fecal and urinary elimination of SAD‐derived radioactivity. These results suggest that the antiteratogenic effect of DMSO against SAD may be at least partly mediated by increased SAD (or its metabolites) retention by maternal liver leading to reduced SAD uptake by the fetus.
Effects of prenatal X‐irradiation on postnatal testicular development and function in the Wistar rat: Development/teratology/behavior/radiation
Authors: Jensh Ronald P. , Brent Robert L.
Published: June 2005

It is evident that significant permanent tissue hypoplasia can be produced following radiation exposure late in fetal development. Because two organs, brain and testes, are developmentally and functionally interrelated, it was of interest to determine whether fetal testicular hypoplasia was a primary or a secondary effect of fetal brain irradiation. Twenty‐four pregnant Wistar strain rats were randomly assigned to one of four groups, and a laparotomy was performed on day 18 of gestation. The fetuses received sham irradiation, whole body irradiation, or only head/thorax or pelvic body irradiation at a dosage level of 1.5 Gy. Mothers were allowed to deliver and raise their offspring until postnatal day 30, when the offspring were weaned. At 60 days of age, 74 male offspring were allowed to mate with colony control females of similar age until successful insemination or until the males reached 90 days of age, when they were killed. Testes were weighed and processed for histologic examination. Direct radiation of testes, due to whole body or pelvic exposure, resulted in testicular growth retardation and significantly reduced spermatogenesis. Breeding activity of the males and the percent of positive inseminations were also slightly reduced. However, a significant percentage of male offspring receiving direct testicular radiation did produce offspring. Head/thorax‐only irradiation did not adversely affect testicular growth or spermatogenesis. Therefore, the use of histologic analysis as the sole determinant of infertility may be misleading. This study indicates that testicular growth retardation and an increased infertility rate result from direct prenatal exposure of rat testes to X‐radiation and are not necessarily mediated via X‐irradiation effects on the central nervous system.
Epidemiological and genetic study of 200 cases of oral cleft in the Emilia Romagna region of northern Italy
Authors: Calzolari E. , Milan M. , Cavazzuti G. B. , Cocchi G. , Gandini E. , Magnani C. , Moretti M. , Garani G. P. , Salvioli G. P. , Volpato S.
Published: June 2005

Epidemiological and genetic variables in clefts were analyzed during the years 1978–1986 in a case‐control study of congenital malformations in the Emilia Romagna region of northern Italy. Among 150,168 newborns, 200 cases of cleft were detected, yielding a prevalence of 1.33 per 1,000. These clefts consisted of 112 (0.075%) cases of cleft lip with or without cleft palate (CL±P) and 88 cases (0.058%) of cleft palate (CP). Coexisting abnormalities were found in 32% of cases. The heritability coefficient of CL±P was 0.84. No cluster in time or space could be demonstrated. Epilepsy was the only maternal risk factor found to be correlated with clefts. A predominance of males was found among CL±P cases.
Quantitative study of the effects of maternal hyperthermia on cell death and proliferation in the guinea pig brain on day 21 of pregnancy
Authors: Upfold J. B. , Smith M. S. R. , Edwards M. J.
Published: June 2005

On embryonic day 21, pregnant guinea pigs were exposed to a 44°C environment for 1 hour. As a result, all brain ventricular zone cells in M phase of the mitotic cycle when heat‐shock occurred became immediately pyknotic and all cell division was stopped for 4–8 hr. The pyknotic cells were removed at a definable rate until mitosis resumed, after which removal occurred in an apparently random manner. Long delays in the return to mitosis were related to increased destruction of S‐phase cells deep within the ventricular zone and largely confined to the alar lamina. Upon recovery, a rostrocaudal delay in mitosis was apparent, and the number of mitotic figures was increased compared with control numbers for 1 hr, after which they returned to control numbers. It was evident that up to 40% of the cells within the ventricular zone were destroyed following brief maternal heat stress.
Teratogenicity of three substituted 4‐biphenyls in the rat as a result of the chemical breakdown and possible metabolism of a thromboxane A2‐receptor blocker
Authors: Sutherland M. F. , Parkinson M. M. , Hallett P.
Published: June 2005

AH23848 is a potent thromboxane A2‐receptor blocker inhibiting platelet aggregation in vitro and in vivo. Oral administration to pregnant rats during days 7–16 of pregnancy, at doeses of 0, 10, 45, or 200 mg/kg twice daily, resulted in dose‐related maternal, embryonic, and fetal toxicity. The most notable observation was herniation of the diaphragm occurring in 1.5 and 100.0% of fetuses at the 45 and 200 mg/kg doses, respectively, when examined at term. A further study at 150 mg/kg twice daily during days 7–16, 7–11, or 12–16 of pregnancy revealed incidences of diaphragmatic hernia up to 42%. Herniation varied from small areas of eventration of membranous diaphragm to fetuses with apparent total absence of the diaphragm. The positions of the hernias in the diaphragm, following dosing over varying periods of organogenesis, reflected the chronology of diaphragm formation in the rat. The teratology of AH23848 was unrelated to its thromboxane A2‐receptor blocker properties but was related to a chemical breakdown product, 4‐biphenylmethanol. Some substituted biphenyl compounds appear to be specific teratogens in the rat, with their effects targeted at the developing diaphragm. A possible mechanism of herniation is the interference with muscularisation of the membranous diaphragm, resulting in weakness and perforation.
Cortisone cure of the eyelid closure defect in lidgap‐stein fetal mice: A dose‐response and time‐response study as a test of the hypomorph hypothesis for the lidgap alleles
Authors: Harris M. J.
Published: June 2005

The lidgap‐Stein mutation is one of a series of alleles that cause the birth defect open eyes in mice. Previously it was known that cortisone administered during pregnancy prevents the defect in some lidgap‐Stein fetuses. In this study, the hypothesis that lidgap‐Stein is a hypomorph of effect intermediate between that of its alleles lidgap‐Miller (least abnormal) and lidgap‐Gates (most abnormal) was tested in a dose‐response, time‐response, and scanning electron microscopic study. Cortisone produced a response at doses of 20–80 mg/kg, with maximum cure of 30% in right eyes, 24% in left eyes, and 13% bilaterally. There was significantly more response in right than in left eyes. The response was slight at doses of less than 20 mg/kg and dropped to zero at the highest dose of 120 mg/kg. Treatment on days 13 or 14 gave the maximum response, with little or no response to treatment on days 10, 11, 12, 15, or 16. Severity of defect, measured as the size of gap in open eyes on day 18, was not reduced as the frequency of open eyes was reduced; most unclosed eyes remained wide open. The much lower level of maximum bilateral response to cortisone in lidgap‐Stein (13%) than in lidgap‐Miller (94%) is entirely compatible with the hypomorph hypothesis.
Fetus amorphus or placental teratoma?
Authors: Stephens Trent D. , Spall Richard , Urfer Alexander G. , Martin Roger
Published: June 2005

A differential diagnosis between fetus amorphus and placental teratoma based on the presence of an umbilical cord and/or skeletal organization in the fetus amorphus has been proposed (Fox and Butler‐Manual: Journal of Pathology 88:137–140, 1964). We report a description of one new case of fetus amorphus, along with the results of a critical reexamination of 96 cases from the literature. Our findings fail to support the proposed criteria for distinguishing fetus amorphus from placental teratomas. We find that the presence or absence of an umbilical cord does not relate at all to the developmental state of the specimen. The extent of skeletal development may be a more valid criterion; however, the internal organization in the fetus amorphus forms an anatomical continuum with that of the placental teratoma, making a differential diagnosis meaningless. Additional research is necessary to solve this dilemma.
A scanning electron microscope study of fetal eyelid closure accelerated by cortisone in SWV/Bc mice
Authors: Juriloff D. M. , Harris M. J.
Published: June 2005

Eyelid closure occurs earlier in SWV/Bc and CBA/J mouse fetuses whose mothers were treated with cortisone on day 14 of gestation than it does in fetuses from untreated mothers. Similar treatment prevents the open‐eyes defect of lidgap—Miller mutant mice, but examination by scanning electron microscope (SEM) has shown differences in the periderm of the closing eyelids of the cortisone‐treated mutant compared with those of untreated genetically normal fetuses. (Untreated mutant eyelids remain wide open and very abnormal.) The present study has examined at the SEM level the accelerated eyelid closure of cortisone‐treated normal strain, SWV/Bc, fetuses to investigate whether the differences from normal in the eyelids of treated lidgap—Miller fetuses are part of the mechanism of the cortisone “cure.”

At the SEM level, cortisone‐accelerated eyelid closure of SWV/Bc fetuses is indistinguishable from that in untreated fetuses. This suggests that the early eyelid closure induced by cortisone in normal strain fetuses represents acceleration of the normal coordinated sequence of events that leads to closure, rather than an abnormality that fortuitously leads to closure. The data also indicate that the cellular abnormalities seen previously in treated lidgap—Miller mutant fetuses are a combination of 1) abnormalities due to the mutation that are not completely reversed by cortisone and 2) normal developmental stages that have become concurrent with the cortisone‐induced late closure in lidgap—Miller mutant fetuses.
Anatomical features associated with preaxial duplication (pd): A recessive mutation in the rat
Authors: Kaneda Masahiro , Teramoto Shoji , Shirasu Yasuhiko
Published: June 2005

Preaxial polydactyly of the fore‐and hindlimbs was found in Wistar‐derived rats in 1978. Genetic analysis indicated that the polydactyly was due to the effects of an autosomal recessive gene (gene symbol; pd) Polydactylous and one to three preaxial extra digits (six to eight digits) in the hindlimbs. Skeletal examination revealed the presence of the extra carpal, metacarpal, and phalangeal bones that seemed to be complete or incmplete duplication of the navicular, greater multangular, first metacarpal, and phalanges of digit I in the forelimbs. In the hindlimbs, extra tarsal, metatarsal, and phalangeal bones were also observed preaxially. These extra elements seemed to be mirror‐image duplications of the talus navicular, second cuneiform, third cuneiform, cuboid, and metatersals and phakanges of digits II‐V with the absence of the first cuneoform, tibnials, first metatarsal, and phalanges of digit I. In addition, morphological changes were observed in the humerus, radius, and ulna in hte forlimbs and femur, tibia, and fibula in the hindlimbs. Especially in the radius andtibia, thickening and bifurcation were found, indicating incomplete duplication of these bones. Based on these findings, the limb anomaly was classfied as preaxial carpometacarpal/tarsometatarsal‐type polydactyly with incomplete duplication of the radius and tibia. The mutan rats had other associated anomalies such as accessory spleens and cryptorchism. The males are sterile, whereas the females breed normally.
Behavioral teratogenic effect of methylmercury and d‐amphetamine: Meta‐analysis and power analysis of data from the collaborative behavioral teratology study of national center for toxicological research
Authors: Tachibana Toshiaki
Published: June 2005

The data of the Collaborative Behavioral Teratology Study (CBTS) were analyzed. Population‐effect sizes were estimated, in terms of confidence intervals, by meta‐analysis. A treatment effect of methylmercury was clearly observed and a dose‐response effect was also observed. On the other hand, no clear treatment effect was observed in the d‐amphetamine study. The effect of auditory startle habituation was very large, although it was limited to the high‐dose group in the methylmercury study. The effects observed for physical landmarks were, as a whole, somewhat larger than those for behavioral measures. There is no clear evidence for sex‐related differences except for activity measures. A curious treatment effect that was not referred to in the CBTS report was observed: eye‐opening day and incisor‐eruption day were hastened by the treatment of methylmercury. Power analysis results showed that obtaining a statistically significant effect for these compounds is very difficult, suggesting that even though published papers reported the significant effect of these compounds there might have been many unpublished experiments that obtained nonsignificant effects. If one uses these compounds as positive controls, a very large sample size will be needed. No highly sensitive test that is reproducible across compounds or dose‐levels was observed among tests employed in the CBTS.
Prenatal α‐difluoromethylornithine treatment: Effects on postnatal renal growth and function in the rat
Authors: Gray Jacqueline A. , Rehnberg Blair F. , Rogers Ellen H. , Lau Christopher , Slotkin Theodore A. , Kavlock Robert J.
Published: June 2005

DFMO (α‐difluoromethylornithine) is a specific irreversible inhibitor of ornithine decarboxylase (ODC), a key enzyme in the biosynthesis of polyamines, which in turn control macromolecule synthesis during cell proliferation. The current study was designed to investigate the effects of inhibition of ODC during discrete prenatal periods on renal growth and function. We administered 5 doses of 500 mg/kg DFMO or saline s.c. to timed pregnant Sprague‐Dawley rats at 12 hr intervals beginning on gestation days (GD) 11, 14, or 17. Half the dams were killed on GD 20 for fetal morphological analyses and half were allowed to go to term. Renal function was assessed on postnatal days (PD) 3, 6, 10, and 14 by tests of basal renal clearance and urinary concentrating ability, and on PD 42–44 we measured serum chemistries. All three gestational treatment regimens resulted in postnatal deficits in general growth. Only in the GD 11–13 treatment group was there evidence of embryotoxicity and neonatal renal pathophysiology. Fetal weights and urogenital morphology were altered following GD 14–16 treatment and there were persistent deficits of renal growth. GD 17–19 treatment was associated only with transient postnatal deficits of renal growth. Thus, inhibition of ODC during critical prenatal periods induced distinct developmental effects. However, there were no associations between impaired renal growth and function. These data indicate that general tissue growth is not always a predictor of physiological development and support the necessity of multifaceted approaches to the understanding of adverse developmental effects.
Neuroblastoma after prenatal exposure to phenytoin: Cause and effect?
Authors: Koren Gideon , Demitrakoudis Demitri , Weksberg Rosanna , Rieder Michael , Shear Neil H. , Sonely Marylin , Shandling Barry , Spielberg Stephen P.
Published: June 2005

We evaluated the causality of the association between intrauterine exposure to phenytoin and postnatal neuroblastoma using an in vitro lymphocyte toxicity assay for phenytoin‐induced reactions in an unusual sibship. In addition, we investigated intrauterine phenytoin exposure in a case series of infants and children with neuroblastoma diagnosed over 17 years at our center. The response of lymphocytes from our index case with neuroblastoma exposed in utero to phenytoin was within the normal range, whereas the mother and a sibling with fetal hydantoin syndrome (FHS) exhibited an intermediate toxicity. None of the 188 case of childhood neuroblastoma diagnosed between 1969 and 1988 had been exposed in utero to phenytoin, indicating that, statistically, the drug cannot be associated with neuroblastoma in more than two cases with this malignancy in our cohort, or in 1.5% of all cases of neuroblastoma. Although our data do not suggest an association between phenytoin in pregnancy and postnatal neuroblastoma, it is still possible that there is an increased risk for neuroblastoma in children with FHS.
Retinoic‐acid‐induced limb‐reduction defects: Perturbation of zones of programmed cell death as a pathogenetic mechanism
Authors: Alles Ajit J. , Sulik Kathleen K.
Published: June 2005

Pregnant C57B1/6J mice were treated with 100 mg/kg body weight of all‐trans retinoic acid in sesame oil on day 11.0 of gestation. Among the live fetuses harvested on day 18 of gestation, 100% had mesomelic defects of the limbs as determined by gross examination and skeletal staining. Control fetuses treated with sesame oil had no observable limb malformations. Some treated and control embryos were harvested 12 hr after treatment and examined for patterns of cell death by using the supravital stain Nile blue sulphate and methylene‐blue‐ and acid‐fuchsin‐stained histological sections. Retinoic‐acid‐induced cell death in the core of the limb was always associated with the zones of programmed cell death as seen in control embryos of comparable stages. This, in concet with previous studies demonstrating excessive cell death in regions of programmed cell death that correlated with subsequent malformations, leads us to conclude that the pathogenesis of mesomelic malformations has a primary association with the phenomenon of programmed cell death.
Brain abnormalities induced by murine cytomegalovirus injected into the cerebal ventricles of mouse embryos exo utero
Authors: Naruse Ichiro , Tsutsui Yoshihiro
Published: June 2005

Murine cytomegalovirus (MCMV) was injected into the cerebral ventricle of mouse embryos on day 13 of gestation after exposing the embryos out of the uterus in the abdominal cavity of the mother. The embryos were allowed to develop to day 18 of gestation, then taken out from the abdominal cavity. Macroscopically, there were four expanded and three distorted brains out of 19 surviving embryos, whereas no brain abnormality was noticed in 13 embryos injected with culture medium instead of MCMV in the same way. Histopathological examination showed hydrocephalic lesions with strong dilatation of the ventricles and atrophy of the cerebral cortex, and inflammatory lesions with granulomatous proliferation of the ventricular walls with disappearance of the cortical zonation. Immunohistochemically, MCMV‐induced nuclear antigen‐positive cells were frequently observed in the wall of the ventricles and occasionally scattered in the cerebral cortex, white matter, and the nucleus basalis. Some fetuses injected with MCMV in the same way were recovered from the abdominal cavities on day 18 of gestation and transferred to foster nurse mothers. They showed massive cerebral necrosis after feeding for 9 days after birth. Brain abnormalities of mouse embryos after intraventricular injection with MCMV may provide an experimental model of brain damage induced by congenital cytomegalovirus infection.
Moebius syndrome: Animal model—human correlations and evidence for a brainstem vascular etiology
Authors: Lipson A. H. , Webster W. S. , Brown‐Woodman P. D. C. , Osborn R. A.
Published: June 2005

The Moebius syndrome consists of congenital seventh nerve palsy associated with other cranial nerve palsies, most often of the sixth, and/or musculoskeletal abnormalities. A retrospective study of the events of pregnancy in 15 cases was undertaken, after a rat animal model showed that abdominal trauma, uterine vessel clamping and handling and hyperthermia caused bilateral brainstem lesions in fetal rats. Eight of the 15 cases surveyed included a possible associated event during pregnancy; hyperthermia, previous uterine surgery, electric shock, failed abortion, prolonged rupture of the membranes, or alcohol abuse. These events can be correlated with animal studies that involve acute uteroplacental vascular insufficiency produced by a variety of methods. The cause of most cases of Moebius syndrome is probably a transient ischemic/hypoxic insult to the fetus.
Susceptible period of nitrous oxide teratogenicity in sprague‐dawley rats
Authors: Fujinaga Masahiko , Baden Jeffrey M. , Mazze Richard I.
Published: June 2005

The susceptible period of nitrous oxide (N2O) teratogenicity was studied in 170 Sprague‐Dawley rats. Seven groups of 20 timed‐pregnant rats were exposed to 60% N2O for 24 hours on each of days 6–12 of gestation; a control group of 30 timed‐pregnant rats was exposed to air on day 9. On day 20 of gestation, dams were killed and reproductive indices were determined; their fetuses were subsequently examined for external, skeletal, and visceral abnormalities. There were no differences among the groups in the number of implantations and live fetuses, mean fetal weight, and sex ratio. The incidence of fetal wastage was higher than control in N2O‐treated groups exposed on days 8 and 11 of gestation. Skeletal malformations of the ribs and vertebrae were increased following exposure on day 9 of gestation. However, the specific minor anomaly, cervical rib, was increased only following exposure on day 8 of gestation. The incidences of right‐sided aortic arch and left‐sided umbilical artery, abnormalities indicative of altered laterality, were increased following exposure on day 8 of gestation. Nitrous oxide administration during organogenesis causes several reproductive defects by mechanisms which remain to be determined.
Teratogenic effects of phenytoin on chick embryos
Authors: Singh Mandavi , Shah G. L.
Published: June 2005

The antiepileptic drug phenytoin was injected into the yolk sac of White Leghorn chick embryos. A dose‐response study was followed by a detailed teratological study using a single dose of 3 mg. The surviving embryos were sacrificed on the 19th day of incubation. The embryos showed a generalized decrease in body weight together with a wide range of malformations. The malformations could be roughly divided into limb, craniofacial, abdominal, and ocular defects, as well as deficiencies in growth. Skeletal defects included hypoplasia of digital phalanges and nails and shortened wings.
Difference in teratogenic potency of ethylenethiourea in rats and mice: Relative contribution of embryonic and maternal factors
Authors: Daston G. P. , Yonker J. E. , Powers J. F. , Heitmeyer S. A.
Published: June 2005

Ethylenethiourea (ETU) is a potent teratogen in the rat but. not in the mouse or any other species tested. Embryotoxic and teratogenic effects are produced in mice only after exposure to 10‐40 times the teratogenic dose of ETU in rats. This study was undertaken to determine whether the difference in sensitivity between rats and mice is due to differences within the embryo, to maternal metabolic differences, or both. Comparably staged rat and mouse embryos (gestation day 10.5 and 8.5, respectively) with intact extra‐embryonic membranes were maintained under identical conditions in whole embryo culture and exposed to static concentrations of ETU for 48 hours. The teratogenic effects of ETU were qualitatively similar in both species, characterized by excessive fluid accumulations in embryonic structures., The most common abnormalities were distended neural tube, especially in the hindbrain, and clear blisters on the caudal region. At least two times as much ETU was required to produce a similar incidence of abnormalities in mice as in rats. Thus, there is some intrinsic difference in the quantitative response of rat and mouse embryos to ETU, but it is insufficient to account for the in vivo discrepancy. The role of maternal metabolism in modifying the teratogenicity of ETU was assessed by adding hepatic S‐9 fractions from Aroclor 1254‐induced rats and mice to whole embryo culture. Rat S‐9 had no effect on ETU teratogenicity. Mouse S‐9 virtually eliminated the formation of abnormalities typical of ETU in both rat and mouse embryos. Decreased exocoelomic fluid osmolality, a physiological effect produced by ETU, also was not observed in embryos exposed to ETU and mouse S‐9. ETU‐typical defects were observed in embryos exposed to ETU and mouse S‐9 which had been treated with carbon monoxide to inactivate its monooxygenase system, indicating that the mouse S‐9 was metabolizing ETU. A surprising result was that adding mouse S‐9 to embryo cultures containing ETU resulted in the formation of abnormalities (principally open neural tube) that were not observed in in vitro rat or mouse embryos exposed to ETU alone, or in mouse embryos in vivo. We believe that the most likely cause of these abnormalities is a putative ETU metabolite, which is rapidly excreted by the dam in vivo, but accumulates to teratogenic concentrations in vitro.
Heat shock affects cell cycling in the neural plate of cultured rat embryos: A flow cytometric study
Authors: Walsh D. A. , Morris Valerie B.
Published: June 2005

The effects of heat shock on cell cycling in the mammalian neuroectoderm were determined by applying heat shocks to cultured rat embryos at the neural plate stage, as part of a study on the teratogenic effects of heat shock on neural development. The heat shocks had been characterized previously (Walsh et al.: Teratology 36:181‐191, 1987) with respect to their effects on the gross morphological development of the rat embryos. The effects on cell cycling were observed in DNA histograms of neural plate cells recorded in a flow cytometer after staining with DAPI. The mild heat shock (42°C for 10 min) arrested cells at entry to S phase. The teratogenic heat shock (43°C for 7.5 min) arrested cells at entry to S phase also but for a longer time and inhibited cycling through S phase. After each arrest, a synchronized peak of cells later entered S phase and progressed through the cycle. The induced‐thermotolerance heat shock, which was the mild heat shock followed after an interval by the teratogenic heat shock, showed that pre‐treatment with the mild heat shock reduced the magnitude of the response to the teratogenic heat shock. The cell‐cycle inhibitor ICRF 159 showed the effects on cycling rates of the heat‐shock treatments. The arrest of cells at entry to S phase by heat‐ shock may function to prevent cells entering DNA synthesis under non‐optimal conditions. We report estimates of proportions of nonproliferative cells in the neural plate of the rat embryos.