bluuebunny/crossref_metadata_2025 huggingface dataset:
Teratogenic effects of nickel chloride on embryonic mice and its transfer to embryonic mice
Authors: Lu Chiung‐Chen , Matsumoto Nobuo , Iijima Sumio
Published: June 2005

Administration of nickel chloride to the pregnant mice on the seventh to eleventh day of their gestational period, resulted in significant embryotoxic effects in terms of an increased resorption rate, a decreased fetal weight, delay in skeletal ossification and high incidence of malformation. Among the cases of fetal malformation, the following malformations were observed to occur at a higher rate of incidence: acephalia, exencephaly, cerebral hernia, open eyelid, cleft palate, micromelia. ankylosis of the extremity, club foot and skeletal anomalies. Most skeletal anomalies were in the form of vertebral and/or rib fusions and were found mostly at thoracic and lumbar levels. The concentration of nickel retained in embryonic tissues was 800 times higher in the exposed compared to control groups and indicated that increased tissue levels of nickel chloride had a toxic influence on the developing embryo.
Embryotoxicity of transplacentally and intraamniotically administered 6‐azauridine in mice
Authors: Dostál M. , Jelínek R.
Published: June 2005

Embryotoxic effects were compared of intramuscularly (im) and intraamniotically (ia) administered 6‐azauridine (Riboazauracil Spofa) in random‐bred mice H‐Velaz. Effects of single doses (0.25 mg, 2.5 mg, 25.0 mg and 250.0 mg for im and 0.0025 mg, 0.025 mg, 0.25 mg and 2.5 mg for ia administration) on days 11, 12, 13 and 14 were evaluated as a sum of dead fetuses and fetuses with cleft lip and/or palate, fetuses with limb deformities and fetuses with deformities constituting the syndrome of caudal regression (hypoplasia of the caudal part of the trunk, absent tail, short tail, curled tail). Considering the sensitivity peaks of the morphogenetic processes which were observed, the dose‐response relationships, the transformation of the teratogenic to a lethal effect and critical period extension with increasing doses, it was found that the effects of ia and im administered 6‐azauridine did not differ. It was concluded that ia administered 6‐azauridine had direct effect on embryonic morphogenetic processes and that this, too, was the essential mechanism of embryotoxicity of im administered 6‐azauridine. The value of the intraamniotic technique for establishing the direct embryotoxic effect is discussed.
The fetotoxic potential of municipal drinking water in the mouse
Authors: Chernoff Neil , Rogers Ellen , Carver Brenda , Kavlock Robert , Gray Earl
Published: June 2005

Mice (CD‐1 strain) were placed on diets containing either municipal drinking water (Durham, North Carolina) or water that had been distilled and passed through cartridges to reduce organics and remove inorganics. After a two‐week acclimation period, animals were bred and pregnancy confirmed by the presence of a sperm plug. During the 8‐month course of the study, approximately 500 pregnant mice were sacrificed on day 18 of gestation and their fetuses examined for visceral and skeletal anomalies. No significant water‐related effects were found on any fetal parameter studied except for a 28.1% incidence of supernumerary ribs in the tap‐water group as compared to 21.1% in the purified‐water group. No differences were noted in the type or occurrence of anomalies between the two groups. A month to month variation was observed in a number of parameters. The degree of variation was similar for the treatment groups, suggesting that these changes might be random fluctuations.
Correlation between mandibular retrognathia and induction of cleft palate with 6‐aminonicotinamide in the rat
Authors: Diewert Virginia M.
Published: June 2005

A single injection of the niacin antimetabolite 6‐aminonicotinamide (6‐AN) late in gestation produces cleft palate in the rat. In order to achieve an understanding of the mechanism of induction of cleft palate, craniofacial growth and palate development were studied in Sprague‐Dawley rats after treatment with 6‐AN on day 15 of gestation. The rats were maintained on a high niacin diet (95 ppm) and subjected to three different teratogenic levels of 6‐AN. The first group was injected with 8 mg/kg, the second was fasted and injected with 8 mg/kg and the third was treated with 16 mg/kg. The lowest teratogenic dose, 8 mg/kg, produced mild mandibular retrognathia on day 16, delayed shelf elevation a few hours and resulted in small rostral and small caudal clefts of the secondary palate. The moderate dose, 8 mg/kg with fasting, produced more severe mandibular retrognathia, delayed shelf elevation about 24 hours and resulted in 37% full clefts and 63% partial clefts of the palate. The highest teratogenic dose, 16 mg/kg, produced severe mandibular retrognathia, delayed shelf elevation by more than 24 hours and resulted in 100% full clefts of the palate. In each 6‐AN group, the most severe mandibular retrognathia was present between days 16 and 17, the critical time for palate closure in the rat. Treatment with 6‐AN also produced abnormality of the epithelial cells of the palate, the toothbuds and the nasal septum. Molar and incisor toothbuds were small and malformed, and the epithelial surfaces of the palate and the soft tissue nasal septum did not fuse.
Cadmium induced limb defects in mice: Strain associated differences in sensitivity
Authors: Layton W. M. , Layton M. W.
Published: June 2005

Cadmium (CdSO4) was given ip on day 9 at 12 or 24 μmol/kg to pregnant CD‐1 (non inbred) mice. Fetuses showed malformations of the limbs, face, trunk, and tail. There was a statistically significant relationship between the dose of cadmium and the malformation rate. Cadmium (12 μmol/kg ip on day 9) was then given to mice of six inbred strains three of which (A/J, BALB/ cJ, and C57BL6J) carry a gene cdm for resistance to cadmium‐induced testicular damage, and three strains (AKR/J, CBA/J, and DBA/2J) which do not. Paradoxically, the three strains resistant to cadmium‐induced testicular damage were significantly more sensitive to its teratogenic effects than were the other three strains. In all inbred strains most malformations involved the limbs. All forelimb defects found in inbred or non‐inbred cadmium treated mice were postaxial and indistinguishable from those produced by acetazolamide in mice. The remarkable similarity of the cadmium‐ and acetazolamide‐induced forelimb malformations may be a reflection of the limited number of ways that a rodent forelimb can react to a teratogenic insult. The hindlimb defects were all preaxial.
Electron microscope observations of embryos from maternal rats treated with trypan blue
Authors: Schmidt Karmen L.
Published: June 2005

Electron microscopic examination of embryos from trypan blue injected maternal rats reveals tissue alterations that may signal forthcoming malformations. Ten‐, eleven‐, and twelve‐day normal appearing embryos from the dye‐treated group demonstrate early tissue changes in hindgut, neural tissue and myocardium. A 1‐μ “halo” vacuole is observed only in treated tissues. The vacuole exhibits a clear periphery enclosing a homogeneous, electron‐dense material. The vacuole is prevalent throughout 10‐day embryonic tissues. In older embryos the halo vacuole is frequently observed within residual bodies, suggesting heterophagic processing. The halo vacuole may contain trypan blue, implicating direct action of the dye upon embryonic cells. Extensive fibrous deposits above the neural plates and within hindgut lumina of dye‐treated embryos demonstrate 230 Å periodicity characteristic of fibrin. In cross‐section the fibrin displays a core of fibrillar material encased by an electron‐dense sheath. Trypan blue may form this core and initiate fibrin polymerization. These extensive accumulations of fibrin probably form in conjunction with dye provoked hemorrhagic blistering. Large intra‐ and extracellular granular deposits occur in dye‐treated myocardium and hindgut epithelium. PAS staining, alpha amylase and ribonuclease digestion identify the granules as glycogen. The ultrastructure and quantity of glycogen is similar to that in glycogen storage disease of man.
Teratogenic effects of the plant hormone indole‐3‐acetic acid in mice and rats
Authors: John J. A. , Blogg C. D. , Murray F. J. , Schwetz B. A. , Gehring P. J.
Published: June 2005

These studies evaluated the teratogenic potential of indole‐3‐acetic acid (IAA), a naturally occurring plant hormone, in CF‐1 mice and Sprague‐Dawley rats. Mice were given 5, 50, 200, or 500 mg IAA/kg/day by gavage on days 7 through 15 of gestation. Rats were given 50, 200, or 500 mg IAA/kg/day by gavage on days 7 through 15 of gestation. IAA was teratogenic in mice and rats at 500 mg/kg/day; cleft palate was induced in both species at this dose level. In mice, other malformations including exencephaly, ablepharia, dilated cerebral ventricles, and crooked tail were also observed. Mice given 500 mg/kg of IAA gained less weight than control mice during gestation; no evidence of maternal toxicity was observed in rats. IAA did not cause fetal resorptions in either species and was not teratogenic at dose levels below 500 mg/kg.
Behavioral consequences of interference with CNS development in the early fetal period
Authors: Rodier Patricia M. , Reynolds Sigrid S. , Roberts W. Neal
Published: June 2005

As a part of a series of investigations into the structural and functional consequences of interference with cell proliferation, mice were treated with 5‐azacytidine during two stages of early fetal life. Treatment on either the twelfth or fourteenth day of gestation led to permanent significant reductions in body weight and brain weight. Behaviorally, the earlier treatment was associated with a delay in development of the righting reflex, permanent deficits in locomotor coordination, and hypoactivity. Treatment on the fourteenth day of gestation led to decreased passive avoidance, increased active avoidance, and hyperactivity — the same syndrome observed after treatment on the eighteenth day. Both treatments led to abnormal behavior on a spatial maze task. The developmental outcome of injuries induced in the early fetal period appears similar to the outcome of injuries at later stages of development.
Teratogenic potential of inhaled carbon monoxide in mice and rabbits
Authors: Schwetz B. A. , Smith F. A. , Leong B. K. J. , Staples R. E.
Published: June 2005

Pregnant CF‐1 mice and New Zealand rabbits were exposed to carbon monoxide at a concentration of 250 ppm for 7 or 24 hours daily during the period of major organogenesis, days 6 through 15 of gestation in mice and 6 through 18 of gestation in rabbits. Carboxyhemoglobin levels in the range of 10–15% were observed in both species (control animals had 0.7% or less). Carbon monoxide was not found to be teratogenic in either species. In mice, a significant increase in the incidence of some minor skeletal variants was observed. One litter in each of the carbon monoxide–exposed groups of mice was completely resorbed; none of the litters of control mice or of control or exposed rabbits were completely resorbed. The fetuses of mice exposed to carbon monoxide for seven hours daily were heavier than control fetuses, and those exposed for 24 hours daily were lighter than control fetuses. The reason for this result is not known.
Selective inhibition of mandibular growth and induction of cleft palate by diazo‐oxo‐norleucine (DON) in the rat
Authors: Diewert Virginia M. , Pratt Robert M.
Published: June 2005

A high percentage of cleft palates can be induced in rat fetuses by a single injection of the glutamine analog diazo‐oxo‐norleucine (DON) on day 15 of gestation. The purpose of this study was to evaluate the effects of DON in vivo on craniofacial growth and spatial relations in order to identify factors that may contribute to the palatal defects. Sprague‐Dawley rats in the experimental groups were given a single IP injection of 2.0 mg DON (6 mg/kg maternal body weight) on day 15 and were killed on day 16 or 17. Control fetuses were collected on days 15, 16 and 17. Fetal heads were fixed in Bouin's solution, embedded in Paraplast and serially‐sectioned. Midsagittal and coronal sections were projected at 30 × and a series of linear and angular measurements were made. DON had limited effect on growth of the cranial base, nasomaxillary complex, and palatine processes, but dramatically reduced the length of Meckel's cartilage. Treatment with DON delayed shelf elevation approximately 24 hours, and tongue position remained high in the oronasal cavity. Growth retardation in Meckel's cartilage therefore may contribute to delayed shelf movement by retarding downward and forward positioning of the tongue‐mandibular complex.
The medical profession and congenital malformations (1900‐1979)
Authors: Warkany Josef
Published: June 2005

Physicians' interest in congenital malformations has varied greatly during the last two centuries. After an acme in the 19th century, teratology was of little interest to the medical profession during the first four decades of the 20th century. Since then a variety of events have again made birth defects important. An attempt is made to explain the waxing and waning of the physicians' attention to this age‐old problem.
The early limb deformity caused by acetazolamide
Authors: Holmes Lewis B. , Trelstad Robert L.
Published: June 2005

Histologic sections were made of the forelimbs of day 10 to 12.5 embryos removed 3, 16, 30, 36, 42, 45, 63 and 75 hours after the intraperitoneal injection of acetazolamide into C57B1/6J pregnant females. A postaxial deformity was first visible in the right forelimb of day 10.9 embryos 36 hours after the second dose of acetazolamide 1,000 mg/kg on day 9 of gestation. The deformity was a postaxial deficiency of mesenchyme tissue without any evidence of cell necrosis. The deformity was present before aggregation of mesenchyme cells occurs as the first step in chondrogenesis. The pattern of cell orientation in the adjacent mesenchyme aggregate of a deformed day 12.5 forelimb was normal. This means that the primary effect of acetazolamide is not on the formation of precartilage aggregates in the postaxial region, but involves other aspects of early limb development.
Aspirin: Teratogenic evaluation in the dog
Authors: Robertson Richard T. , Allen Henry L. , Bokelman Delwin L.
Published: June 2005

Beagle bitches were administered aspirin at either 100 or 400 mg/kg/day between Days 15 and 22 or Days 23 and 30 postmating, and corresponding control groups were dosed with vehicle during one of these same time periods. Maternotoxicity was evident in all dogs dosed with 400 mg/kg/day of aspirin, but no signs of toxicity were observed in dogs at the lower dosage level. An increase in the number of resorptions was observed when 400 mg/kg/day of aspirin was administered from Days 16 to 22 postmating. Teratogenicity, as evidenced by 50% malformation rate, was seen in fetuses from dams treated with 400 mg/kg/day on Days 23 to 30 postmating. Observed malformations included, but were not limited to cleft palate, micrognathia, anasarca, cardiovascular malformations, and tail anomalies. No evidence of embryotoxic or teratogenic effects was seen in fetuses from either 100 mg/kg/day dosage level group. Examination of fetuses from 12 untreated litters and 4 vehicle‐control litters revealed a very low spontaneous malformation rate confined almost entirely to minor tail abnormalities. These data support use of the dog as an acceptable alternative species in teratogenic screening.
The Murine Ah locus: In utero toxicity and teratogenesis associated with genetic differences in benzo[a]pyrene metabolism
Authors: Shum Shu , Jensen Nancy M. , Nebert Daniel W.
Published: June 2005

Benzo[a]pyrene, at doses between 50 and 300 mg per kg body weight given at Day 7 or 10 of gestation, causes in utero toxicity and teratogenicity more so in genetically “responsive” C57BL/6 than in “nonresponsive” AKR inbred mice. With the use of AKR × (C57BL/6)(AKR)F1, and (C57BL/6) (AKR)F1 × AKR backcrosses, it was shown that allelic differences at the Ah locus in the fetus can be correlated with dysmorphogenesis. If the mother is nonresponsive (Ahd/Ahd), the Ahb/Ahd genotype in the fetus is associated with more stillborns and resorptions, decreased fetal weight, increased congenital anomalies, and enhanced P1,‐450‐mediated covalent binding of BP metabolites to fetal protein and DNA, when compared with the Ahd/Ahd genotype in the fetus from the same uterus. If the mother is responsive (Ahb/Ahd), however, none of these parameters can be distinguished between Ahb/Ahd and Ahd/Ahd individuals in the same uterus, presumably because enhanced BP metabolism in maternal tissues and placenta cancels out these differences between individual fetuses.

Of particular interest in our study is the fact that the mother and the father both must be of a particular genotype before differences in teratogenesis among fetuses (due to their genotype) will be expressed. These data might provide an example in attempting to explain clinically why only one child is affected with an apparent “drug‐induced syndrome” although the mother has taken the same dose of the particular drug during each of numerous pregnancies.
Fetal tissues from various strains of induced mice metabolize benzo(a)pyrene to mutagenic metabolites
Authors: Blake David A. , Martz Fred , Gery‐Martz Ann , Gordon Gary B. , Mellits E. David
Published: June 2005

Since metabolic activation is known to mediate mutagenic and carcinogenic actions of certain chemicals, it is possible that embryopathic effects might also result from formation of reactive metabolites in fetal tissue. We evaluated this possibility by examining the activation of BaP 3 by fetal mouse liver homogenates ( + NADPH) to a mutagen(s) active in the “Salmonella‐microsome” assay. Three inbred mouse strains known to have high (B6), intermediate (C3H) and low (D2) inducibility of AHH and one random bred strain (CD1) were tested on gestational day 17, four days after an enzymeinducing dose of polychlorinated biphenyls. BaP induced TA1538 revertants in the presence of fetal liver homogenates from all strains with the order of activity being CD1 > B6 > C3H > D2. Although the number of revertants per mg fetal liver protein was only 5–10% of that found with maternal liver, it was linearly related to induced AHH activity measured by the fluorescence procedure. In contrast, the mutagenizing activity of placenta and whole fetus (minus liver) was lower than fetal liver and did not correlate with induced AHH activity. Activating potency did not correlate with either EH activity or the ratio of AHH/EH in maternal liver, fetal liver or placenta. These results support the postulated mechanism for embryopathic effects of chemicals that undergo metabolic activation to reactive metabolites and provide an explanation for genetically determined variation in response.
Amphetamines reduce embryonic size and produce caudal hematomas during early chick morphogenesis
Authors: Kolesari Gary L. , Kaplan Stanley
Published: June 2005

Experiments were designed to study some of the similarities and differences in the effects of amphetamines and trypan blue on early chick morphogenesis. Both dextroamphetamine sulfate (0.5 mg/egg) and methamphetamine hydrochloride (1.0 mg/egg) were capable of inducing, in 3‐day chick embryos, caudal hematomas which were similar in appearance and location to those routinely observed following treatment with trypan blue. It was found, too, that both dextroamphetamine and methamphetamine treated embryos frequently exhibited a significant decrease in crown rump length and cross‐sectional area of the notochord, neural tube, dorsal aortae and whole body section, when compared with unopened or saline injected controls. Trypan blue treated embryos had only a rare decrease or increase in the size of structures when compared to either control group. These findings suggest that the amphetamines have an ability to decrease or retard embryonic growth in the chick.
Correlation between the growth inhibitory effects, partition coefficients and teratogenic effects of lipophilic acids
Authors: Freese E. , Levin B. C. , Pearce R. , Sreevalsan T. , Kaufman J. J. , Koski W. S. , Semo N. M.
Published: June 2005

The inhibition of cell duplication by many lipophilic acids was measured in Bacillus subtilis and in the following mammalian cell lines, the hunran epithelial‐type cell lines HeLa, strain R and strain L‐132, the human fibroblast cell line VA‐13, and the rat glial cell line C. The results were correlated to the partition coefficient and the distribution coefficient (= apparent partition coefficient at pH 7.2) of the compounds, using octanol/water partition coefficients and pKa values either from the literature or measured for this work. For B. subtilis, the logarithm of the inhibitory potency of most compounds increases linearly with the logarithm of the partition coefficient. Exceptional high potencies were observed for compounds that can efficiently delocalize the charge of the negative ion over the whole molecule. Most compounds inhibit tissue cultures at least as potently as they inhibit B. subtilis. But some compounds are significantly more potent in tissue cultures than would have been expected from the B. subtilis data; such compounds (analgesics/antipyretics, anti‐inflammatory compounds, but rate, norepinephrine) presumably inhibit mammalian cells by specific reactions with certain cell components. However, most compounds inhibit the different cell lines to a similar degree, indicating no cellular specificity; exceptions to this rule are chlorambucil, chlortetracycline and dexamethasone.

Many of the lipophilic acids that are potent inhibitors of mammalian cell replication are also teratogenic. Exceptional compounds may not reach the embryo. We propose that a number of other lipophilic acids that are potent inhibitors and to which humans are frequently exposed should be tested for their teratogenic effect.
A study of spontaneoulsy aborted twins
Authors: Livingston J. E. , Poland B. J.
Published: June 2005

Fifty‐three pairs of twins were obtained during examination of 1,939 spontaneously aborted complete embroys and fetuses. Therefore, the rate of twinning in pregnancies which spontaneously aborted was about 1 in 35. The spontaneous twin abortions consisted of 25 sets of twin embroys, 26 sets of twin fetuses, and two sets in which one was an embryo and one was a fetus. It was possible to determine the zygosity in 37 pairs. The ratio of monozygotic to dizygotic was 17.5:1. About 88% of the twin embryos and 21% of the twin fetuses were abnormal. These abnormality rates were similar to those observed in the overall study of the abortuses. The data on spontaneously aborted twins were compared with data on liveborn twins. The results suggest that twinning, particularly MZ twinning, occurs more frequently than has been thought, based on newborn data, and that embryonic and fetal mortality is much higher in twins than in singletons.
Dermatoglyphic abnormalities in the fetal alcohol syndrome
Authors: Qazi Qutub H. , Masakawa Akiko , McGann Barbara , Woods James
Published: June 2005

Dermatoglyphics of 19 male and 23 female patients with fetal alcohol syndrome were compared with those of matched controls. Both male and female patients differed in several of the dermatoglyphic characteristics from their sex‐matched controls. The abnormalities of dermatoglyphics reported here constitute a valuable marker trait of the teratogenic effect of the alcohol on fetal development and provide additional diagnostic signs for the fetal alcohol syndrome.
Genetic maternal effects on cleft lip frequency in A/J and CL/Fr mice
Authors: Juriloff D. M. , Fraser F. C.
Published: June 2005

Two related strains of mice, A/J and CL/Fr, differ in the frequency of spontaneous cleft lip produced in term fetuses: 10% versus 25%. In order to examine the nature of the genetic basis for this difference, various crosses between the strains were made. The results indicated that genes acting in the mothers, rather than in the embryos, caused the strain difference, and that their effect may be on CL(P) embryo survival rather than occurrence. The A/J strain alleles were dominant to those of CL/Fr, and a one‐locus difference can explain the data.

The importance of genetic maternal effects on CL(P) frequency in mice, with dominance, should be borne in mind when the polygenic, additive threshold model is applied to human data. Neither effect is allowed within the model, yet if the traits are homologous between species, these effects may well be present in man as in the mouse.
The use of cultured rat embryos to evaluate the teratogenic activity of serum: Cadmium and cyclophosphamide
Authors: Klein Norman W. , Vogler Mary A. , Chatot Clare L. , Pierro Louis J.
Published: June 2005

Head fold stage rat embryos were cultured for 48 hours in vitro on serum taken at various intervals from rats that had been injected ip with either cadmium or cyclophosphamide. Their response was compared to that of embryos cultured for the same period on control serum to which these substances were added directly. One and 4 hour sera from cadmium‐injected rats (2.13 mg Cd++/kg) were lethal. Eight hour serum allowed survival but embryos were exencephalic and contained reduced amounts of protein and DNA. The response to direct cadmium was characteristically different and was related to dosage and the extent to which zero‐time embryos had progressed through the head fold stage. At 1.6 μM, Cd++ susceptible embryos were hemorrhagic, though not exencephalic. One hour serum from rats given cyclophosphamide (180 mg/kg) was lethal. On 4 hour serum, embryos survived but were exencephalic and contained less protein and DNA than controls. Embryos were resistant to direct cyclophosphamide up to 800 μg per ml of medium. At this concentration, embryos appeared morphologically normal but contained reduced amounts of protein.
Teratogenicity of diphenylhydantoin in the New Zealand white rabbit
Authors: McClain R. M. , Langhoff L.
Published: June 2005

The teratogenic potential of diphenylhydantoin sodium (DPH) was investigated in the rabbit after oral intubation of 0 (Control), 25, 50, 75, 100, and 150 mg/kg/day from days 7–18 of gestation. Except for reduced maternal weight gains at the two higher dosages, no other obvious pharmacological or toxic effects were noted in treated rabbits.

Dose‐response‐related increases in the resorption and malformation rates were observed. Four litters (one of 14 litters with viable fetuses at 75 mg/kg/day and three of eight litters with viable fetuses at 100 mg/kg/day) exhibited a similar pattern of multiple malformations that included some or all of the following defects: open eyes, cleft palate, and limb abnormalities that included shortened and curved long bones, pes caves, syndactyly, and ossification defects of the phalanges. Dosages of 150 mg/kg/day produced nearly complete resorption, which may have masked the teratogenic response to the drug.
Influence of formaldehyde and sonacide® (potentiated acid glutaraldehyde) on embryo and fetal development in mice
Authors: Marks Thomas A. , Worthy William C. , Staples Robert E.
Published: June 2005

Pregnant outbred albino mice were given formaldehyde or Sonacide® (potentiated acid glutaraldehyde) by gavage on days 6–15 of gestation. The mice were killed on day 18, the general health and reproductive status of the dam evaluated, and the fetuses examined and processed in order to characterize external, visceral, and skeletal malformations. Although formaldehyde (stock solution containing 12–15% methanol as a preservative) was lethal to 22 of 34 dams treated with 185 mg/kg/day, and one of 35 dams treated with 148 mg/kg/day, these doses did not produce statistically significant (two‐sided p < 0.05 versus controls) teratogenic effects in the fetuses of the surviving dams. Sonacide® was also judged not to be teratogenic to the mice employed in this study, in spite of the fact that relatively high doses were employed. The highest doses of Sonacide® studied (5.0 ml/kg/day, which is equivalent to 100 mg/kg/day of glutaraldehyde) killed 19 of 35 dams and caused a significant reduction in the mean weight gain of the surviving mothers. In addition, this dose produced a significant increase in the number of stunted fetuses.
The effects of cytochalasins on the ultrastructure of neurulating hamster embryos in vivo
Authors: Wiley M. J.
Published: June 2005

Single intraperitoneal injections of cytochalasin B (CB) in dimethylsulfoxide were given to gravid Syrian hamsters on the eighth day of pregnancy at various dose levels. Exencephaly and encephalocele, the only defects which were seen in the term litters, occurred in dose‐response patterns reaching peak frequencies of 14.9% and 53.2%, respectively, at the highest dose level, while accompanied by a mortality of 27.7% of implantations. Although these abnormalities were the same as those resulting from cytochalasin D (CD) treatment at this time, the frequencies were lower and the distribution of defects somewhat different. Morphological comparison of embryos fixed at various times after maternal treatment with 7.0 mg/kg CB or 1.5 mg/kg CD demonstrated qualitatively similar changes in response to either teratogen, leading to failure of the cranial neural folds to approximate and close. The principal ultrastructural changes involved alterations in the topography of the apical membranes of neuroectoderm cells. At doses which produced high frequencies of gross defects in the term litters, no changes were seen in the apical bundles of microfilaments in these cells, although much higher dose levels did disrupt these structures. The results support the hypothesis that the cell membrane is the primary target of these teratogens in vivo.
The fetal alcohol syndrome in mice: Maternal variables
Authors: Chernoff Gerald F.
Published: June 2005

CBA, C3H, and C57 female mice maintained on a diet of 20 percent ethanol‐derived calories prior to and throughout gestation were mated in a diallele cross. Prenatal death, malformations, and fetal weights were directly related to maternal blood alcohol levels, indicating a maternal effect. Fetal abnormalities and maternal blood alcohol levels varied with maternal strain (CBA > C3H > C57) and were inversely related to maternal alcohol dehydrogenase activity. Microsomal ethanol oxidizing systems induction was directly associated with increased fetal abnormalities, being greatest in CBA females. These results indicate that liability for the pattern of malformation observed in this syndrome is dependent on maternal blood alcohol levels, which are determined by the rate of maternal alcohol metabolism as well as the amount of maternal alcohol consumption.
Anatomical defects in a case of trisomy 13 with a D/D translocation
Authors: Aziz M. Ashraf
Published: June 2005

Gross morphological defects and variations in a cytogenetically confirmed case of trisomy 13 with t (D/D) are described comprehensively for the first time. The subject, a female neonate, exhibited the following clinical features: microcephaly, sloping forehead, coloboma of the iris, bilateral cleft lip and palate, short neck, and postaxial extra digits on hands and feet. Visceral anomalies included: dextrocardia; hypertrophied right ventricle; common atrium; hypertrophied sinus venosus; persistent left superior vena cava; a large, patent ductus arteriosus interventricular septal defect; Meckel diverticulum; common mesentary; omphalocele; accessory renal arteries and veins; bicornuate uterus; bilateral agenesis of the olfactory bulb; partial holoprosencephaly; and the ulnar nerve passed anterior to the medial epicondyle, bilaterally. Supernumerary muscles included: pectorodorsalis (“achselbogen”); chondroepitrochlearis; sternochondroscapularis; accessory heads of biceps brachii; and radiocarpus. The following muscles were absent: stylohyoideus; pectoralis minor (left); subclavius; palmaris longus and brevis; plantaris; and peroneus tertius. The following muscles exhibited unusual variations: digastricus; mylohyoideus; pectoralis major; and extensor indicis. These findings are compared and contrasted with those recently reported in primary trisomy 13 and 18 and with a case of trisomy 13 with a D/G translocation.
Regional differences in the effects of glucocorticoids on maturation of the fetal skeleton of the rat
Authors: Mosier H. David , Dearden Lyle C. , Roberts Rosalinda C. , Jansons Regina A. , Biggs Cynthia S.
Published: June 2005

The effects of glucocorticoids on fetal growth and development in the rat were investigated. Pregnant rats were injected subcutaneously on gestational days 12 and 13 with betamethasone (0.18 or 0.42 mg), with dexamethasone (0.12 or 0.24 mg), or with physiological saline. Fetuses at day 21 of gestation were weighed, cleared, and stained for calcification with Alizarin Red S. Fetal weight was significantly reduced at both dose levels of each steroid; a greater reduction occurred with the higher dose. Retardation of growth and of calcification of bones in the axial skeleton occurred at both doses; there was greater retardation with the high dose. In the appendicular skeleton there was enhanced calcification of some bones with the low dose, and a retardation of calcification with the high dose of each steroid.

The present findings show that different regions of the fetal skeleton may respond discordantly to the effect of glucocorticoids depending on the dose.
The effect of vitamin A on fusion of mouse palates. II. Retinyl palmitate, retinol, and retinoic acid in vitro
Authors: Newall D. R. , Edwards J. R. G.
Published: June 2005

A fixed‐exposure culture technique is described using palatal shelves removed from mouse fetuses on day 14 of pregnancy. In this technique growth is eliminated as a possible variable. The addition of retinyl palmitate, retinol, or retinoic acid to culture medium at concentrations similar to those found associated with cleft palates produced in vivo after dosing dams with vitamin A on day 14 prevented fusion of explanted shelves in vitro after a 24‐hour exposure period. Retinoic acid prevented fusion of explants after as little as 4 hours exposure. Retinoic acid was more active in vitro than retinol, which was itself eight to ten times more active than retinyl palmitate. An explanation of the effect of vitamin A on the fusing mouse palate is given based on altered glycoprotein synthesis.
Effect of retinoic acid upon the chick embryonic morphogenetic systems. I. The embryotoxicity dose range
Authors: Jelínek R. , Kistler A.
Published: June 2005

The effects of all‐trans‐beta‐retinoic acid upon the developing chick embryo were investigated using the Chick Embryotoxicity Screening Test (CHEST). A dose of 0.3 μg, injected subgerminally in stages HH 10–11, arrested the neural tube development, disturbed extraembryonic vasculogenesis, and induced formation of haemorrhagic blisters in the caudal region. Single administration of retinoic acid on days 2,3, and 4 revealed a stage‐specific effect. Being high, due to the abundant mortality of embryos injected on day 2, the effect drops conspicuously on day 3, and rises once again on day 4 when a remarkable proportion of the surviving fetuses suffer from serious morphological damage comprising cardiovascular lesions, maldevelopment of the central face, and dysmelia. The target tissues are similar to those of vitamin A in developing mammals. The increased sensitivity of chick embryo morphogenetic systems between days 3 and 4 supports the hypothesis that the deleterious action of retinoic acid is due to the development of specific binding sites in the target cell populations.
Comparative ultrastructural alterations in rabbit limb‐buds after a teratogenic dose of either hydroxyurea or methotrexate
Authors: Desesso John M.
Published: June 2005

Early changes in rabbit limb‐bud fine structure subsequent to maternal administration of either hydroxyurea (750 mg HU/kg) or methotrexate (19.2 mg MTX/kg) on gestational day 12 have been analyzed in order to identify the morphologic sites of teratogenic action. Forelimb‐buds were examined at 15 minutes to 32 hours posttreatment for ultrastructural alterations. HU caused early dispersion of ribosomes, condensation of nuclei, segregation of the granular portion of the nucleoli, and eventual fragmentation of mesenchymal cells. As a consequence of the extensive mesenchymal cellular death, the intercellular space among the remaining viable cells was increased. Cellular debris from fragmented cells was seen phagocytized within cells and in the intercellular space. In contrast, MTX caused an increase in cytoplasmic lipid, angular contours of nuclei, but relatively little cellular death. The most prominent change was a disruption of the normal mesenchymal architecture characterized by greatly increased intercellular space and a consequent reduction in the number of intercellular junctions. Nearly normal cytoarchitecture was restored by 32 hours. It was concluded that the primary morphologic sites of action are indeed different. Nevertheless, MTX and HU shared a common denominator since both caused disruption of intercellular contacts and possible breakdown of intercellular communication: HU through cytolethality, and MTX via disruption of intercellular junctions. This latter phenomenon may help to explain the similarities in limb defects caused by these two drugs.
Comment on the prune belly syndrome: An 11‐week fetus with megacystis
Authors: Barr Mason , Burdi Alphonse R.
Published: June 2005

An 11‐week human fetus with megacystis, prostatic dysgenesis, and lateral displacement of the abdominal muscles is described. We suggest that a subtle outflow obstruction of the very early bladder may give rise to both bladder dilation and bladder wall dysgenesis. The bladder dilation may produce abdominal muscle dysplasia or atrophy and almost certainly produces dilation of the prostatic urethra. The dilation of the prostatic urethra disrupts the formation of the prostate.
Teratogenic effects of aliphatic nitriles
Authors: Willhite Calvin C. , Ferm Vergil H. , Smith Roger P.
Published: June 2005

Intraperitoneal injection of acrylonitrile at 1.51–2.26 mmole/kg (80–120 mg/kg) or propionitrile at 0.54–1.51 mmole/kg (30–83 mg/kg) on the morning of Day 8 of gestation in the hamster induced exencephaly, encephalocoeles, and rib fusions and bifurcations in the offspring. These doses of the aliphatic nitriles also resulted in obvious toxicity to the dams. Multiple intraperitoneal injections of sodium thiosulfate at 4.03 mmole/kg (1 gm/kg) protected both dams and embryos against toxicity. When the larger doses of either acrylonitrile or propionitrile were given in the presence of sodium thiosulfate, teratogenic effects were observed in the absence of overt signs of maternal poisoning. A survey of the literature describes many studies which demonstrate that acrylonitrile and propionitrile are converted in vivo to toxicologically significant concentrations of cyanide and that sodium thiosulfate, an established cyanide antagonist, can provide protective actions against poisoning by either acrylonitrile or propionitrile. The observations suggest that the teratogenic effects of both acrylonitrile and propionitrile are related to the metabolic release of cyanide.
Diazepam‐induced neural tube closure defects in explanted early chick embryos
Authors: Nagele R. G. , Pietrolungo J. F. , Lee H. , Roisen F.
Published: June 2005

The effects of diazepam on the development of explanted stage 4 chick embryos were investigated. Diazepam, at 10–120 μg/ml, preferentially inhibited closure of the neural tube. This effect was reversible. Concentrations of 150–200 μg/ml inhibited not only neural tube closure but also blastodermal expansion, somite formation, and heart development in 52% of the embryos. Concentrations above 200 μg/ml were highly embryotoxic. Electron microscopy of affected neuroepithelial cells revealed that (1) apical surfaces were much smoother than usual and (2) apical filament bundles, which are generally thought to provide motive forces for uplifting of neural folds, were not well organized and often lacked alternating dark and light areas along their length. These findings and the fact that changes in cell surface topography reflect the contractile activities of underlying filament bundles suggest that the observed “smoothing” effect on apical cell surfaces and neural tube closure defects are due, at least in part, to the impaired ability of these filament bundles to contract.
Modification of the teratogenicity and mutagenicity of cyclophosphamide with thiol compounds
Authors: Hales Barbara F.
Published: June 2005

Cyclophosphamide must be metabolized to have either therapeutic or toxic effects; many of the major metabolites of cyclophosphamide interact with thiol compounds. To characterize the relationship between the teratogenic and mutagenic metabolites of cyclophosphamide, the effect of thiol compounds on the teratogenicity and mutagenicity of this drug was studied. The effect on teratogenicity was assessed in vivo by treatment of rats with thiol compounds or thiol‐depleting agents prior to administration to cyclophosphamide on day 13 of gestation. The effect on mutagenicity was measured in vitro with a bacterial mutagenicity test using Salmonella typhimurium TA 1535. The administration of thiol compounds (glutathione or cysteine) decreased the teratogenicity of cyclophosphamide, whereas the administration of a thiol‐depleting agent (diethyl maleate) increased its teratogenicity. Low concentrations of glutathione (0.1–1.0 mM) increased the mutagenicity of cyclophosphamide; this effect was not observed with S‐methylglutathione or other thiol compounds. Higher concentrations of glutathione (10 mM, reduced or oxidized) and cystine, but not cysteine, decreased the mutagenicity of cyclophosphamide. Reduced dithiothreitol also decreased the mutagenicity of cyclophosphamide but was toxic in experiments in vivo so its effect on teratogenicity could not be evaluated. Thus, thiol compounds modify both the teratogenic and mutagenic effects of cyclophosphamide. Low concentrations of glutathione (the addition of glutathione in mutagenicity experiments or the depletion of endogenous glutathione in teratogenicity experiments) increased both the mutagenicity and the teratogenicity of cyclophosphamide, whereas high concentrations of this or other thiol compounds decreased these toxic effects. It may be possible to exploit the protective effect of thiol compounds clinically by using thiols to protect pregnant women from the teratogenic effects of inadvertent or intentional administration of cyclophosphamide.
Genetic aspects of the effects of methylmercury in mice: The incidence of cleft palate and concentrations of adenosine 3′:5′ cyclic monophosphate in tongue and palatal shelf
Authors: Harper Kenneth , Burns Risa , Erickson Robert P.
Published: June 2005

Concentrations of adenosine 3′:5′ cyclic monophosphate (cAMP) were measured in the tongues and palates of 14.5‐day‐old fetuses from control and methylmercury‐treated mothers of four inbred lines of mice which represent the four possible combinations of two H‐2 alleles and two residual genetic backgrounds. The incidence of cleft palate in fetuses from control and methylmercury‐treated mothers was also examined. The H‐2 alleles significantly affected the degree of reduction of cAMP concentration in palates seen in fetuses from mothers treated with methylmercury. Neither the H‐2 allele nor the residual genetic background played a role in the effect of methylmercury on cAMP concentrations in fetal tongues. The magnitude of increase in the incidence of cleft palate with methylmercury treatment was approximately the same for all lines. Thus, methylmercury‐induced cleft palate may not be mediated by the reduction of cAMP. Finally, fetuses with cleft lip had increased palatal cAMP levels, whether or not they were from control or methylmercury treated mothers.
Amelioration of teratogenesis. I. Modification of hydroxyurea‐induced teratogenesis by the antioxidant propyl gallate
Authors: DeSesso John M.
Published: June 2005

Hydroxyurea (HU) is a potent teratogen which caused 100% embryotoxic effects in New Zealand white rabbits when injected sc on gestational day 12. These included a high percentage of resorptions and severe craniofacial, trunk and limb deformities of all survivors. Co‐treatment of pregnant animals with the phenolic antioxidant propyl gallate (PG) resulted in amelioration of the embryotoxicity. Various amounts of PG (362–906 mg/kg) and HU (600–750 mg/ kg) were either injected simultaneously or mixed together for periods of time up to 45 min. The extent of amelioration was dependent upon the amount of PG, although the highest dose of PG caused maternal toxicity. Simultaneous injections of HU and PG were not as efficacious as mixture of the two chemicals prior to injection. The length of time which the HU and PG mixture was allowed to stand prior to injection had no effect on the extent of amelioration. The protective action of PG resulted in significant linear reductions in both resorptions and specific malformations with increasing doses of PG. Histologic analysis of HU and HU‐PG embryos disclosed that HU produced rapid cell death in the mesenchymal compartment of the embryo, particularly in the limb‐buds, beginning at 2 h after treatment. Cell debris increased in amount until 8 h and remained extensive at 16 h. In contrast, HU‐PG delayed the onset for cell death until 8 h. Nevertheless, at 16 h, the amount of cell debris in the limb‐buds was appreciable. Thin layer chromatography (TLC) of HU‐PG solution revealed no breakdown products or intermediate compounds suggesting that HU and PG do not react chemically. The presence of HU within both HU and HU‐PG treated embryos was confirmed by TLC of embryonic sonicants. In contrast, TLC of embryonic extracts revealed PG only in HU‐PG embryos. Light microscopy of other embryos from those same litters demonstrated extensive cell debris in the HU embryos but not in HU‐PG embryos. It is suggested that the delay in onset of HU cytotoxicity is caused by the antioxidant properties of PG acting within the embryos, and that this may account for the amelioration of HU teratogenesis by PG.
Quantitation of rat embryonic development in vitro: A morphological scoring system
Authors: Brown Nigel A. , Fabro Sergio
Published: June 2005

In order to realize the maximum potential of whole‐embryo culture techniques, definitive parameters must be developed for the quantitative estimation of embryonic growth and development. An objective scoring system has been devised which provides a precise measure of morphological development. Examination of rat conceptuses from dams on pregnancy days 10, 11, 12, and 13 (sperm positive = day 1) led to the selection of 17 morphological features for use in the system. Up to six developmental stages of each feature were defined and assigned scores of 0 to 5. The numerical total of scores for an individual embryo is taken as the overall morphological score (MS), The system was applied pro‐spectively to 103 Sprague‐Dawley rat conceptuses aged 9 to 12.7 days (0 = time of copulation). The variation of score with embryonic age (EA, days) was highly linear: MS = −202.28 + 20. 932 EA (R2 = 0.991). Thus, the morphological score can be used to compute apparent embryonic age, and the calculated standard error of prediction is ± 2.2 hrs. The number of somites (SN) was also found to vary linearly with age over this period: SN = −126.23 + 13.217 EA(R2 = 0.982), and could be used to estimate development. However, the standard error for prediction of apparent embryonic age is greater (± 3.1 hours) than that for morphological score, and this single feature will not necessarily reflect overall development.

Several parameters were examined as estimates of embryonic growth, as distinct from development. Yolk sac diameter, crown‐rump length, and head length were found to vary with EA as quadratic functions over this time. Total embryonic protein increased logarithmically with EA and was considered to be the most suitable measure of embryonic growth.

Use of the morphological scoring system in embryo culture experiments provides a precise index of embryonic development, aids the detection of retardation or dysmorphogenesis of specific primordia, and allows a quantitative comparison of development and growth.