bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of the embryonic trisomy 1 mouse
Authors: Smith Barbara S. , Pettersen James C.
Published: June 2005

Trisomic and normal control embryos 9.5 through 12 gestational days were examined externally and on serial section with standard light microsopy techniques. Trisomic embryos showed significant retardation in length, weight, optic angle, and somite numbers at most times (p < .05), and were 1/2 day behind normal animals in overall development. The eye showed the most defects, and these appeared at every period. They included aphakia, large intraretinal space, and dysmorphia of optic cup layers. Brain defects were found at all times. The most common were narrow brain vesicles and folding of the vesicle walls. Some animals showed neural tube defects. The major defect in neural crest derivatives was deficient frontonasal processes in the most defective embryos. The study supports the conclusion of previous investigators that Ts 1 is a syndrome of growth and developmental retardation with a wide range of defects. Definitive evidence, previously lacking, indicates that developmental delay and defective morphogenesis are apparent before 11 days of gestation. In addition, according to our measurements, optic angles are larger in trisomic mice than in normal littermates. This is in contrast to the only previous investigation that included such measurements. Our data do not give definitive support to the suggestion that trisomy 1 belongs to the holoprosencephaly‐cyclopia spectrum. However, the hypothesis that murine trisomy 1 shows a parallel in development to human trisomy 13 is not supported by our data. Possible causal mechanisms for the defects and developmental delay are discussed.
Pathogenesis of median facial clefts in mice treated with methotrexate
Authors: Darab D. J. , Minkoff R. , Sciote J. , Sulik K. K.
Published: June 2005

Methotrexate (MTX), administered as a single 20 mg/kg intraperitoneal dose to C57Bl/6 J mice on their 9th day of pregnancy results in high incidences of median facial clefts in the surviving gestational‐day‐18 fetuses. We have shown the presence of dilated and congested blood vessels in the frontonasal prominences (FNP) of embryos from treated mothers as early as 3 hours following drug administration. Within 24 hours, large vascular blebs are located in the FNP and the neural tubes appear somewhat distended. By 32 hours after treatment, distention of the neural tube is marked while blebs have become less evident. Subsequent to these changes, FNP mesenchymal deficiency as well as neural tube distention lead to the formation of median facial clefts. It is hypothesized that, as with a number of other teratogenic agents (especially hypoxia), initial fluid imbalance is the primary teratogenic insult.
Cardiovascular malformations induced by bromodeoxyuridine in the chick embryo
Authors: Nishibatake Makoto , Kargas Steve A. , Bruyere Harold J. , Gilbert Enid F.
Published: June 2005

For the study of morphogenesis and early embryonic development, 5‐bromodeoxyuridine (BUdR), a halogenated analogue of thymidine, is incorporated into replicating DNA and serves as a valuable tool. To study the teratogenicity of BUdR on the developing chick cardiovascular system, we topically administered graded doses of BUdR (32.6–325.6 nmol) in ovo during Hamburger‐Hamilton stages 15 to 16. We also administered to a parallel group of embryos corresponding nanomole doses of thymidine during identical stages of development. In the thymidine‐treated group, survival rates and cardiovascular anomaly rates did not differ statistically from those in the chick Ringer's control group. Both survival rates and cardiovascular anomaly rates in the BUdR‐treated group were dose‐responsive. Among 78 embryos with cardiovascular anomalies induced by BUdR, vascular malformations were found in 96%. These anomalies included interruption of the right fourth aortic arch, absence or hypoplasia of the right and/or left sixth aortic arch, and persistence of the left fourth aortic arch. Interruption, of the right fourth aortic arch was always associated with intracardiac anomalies. Intracardiac anomalies were found in 54% of the embryos; these included ventricular septal defect, double outlet right ventricle, and persistent truncus arteriosus. Subclavian artery malformations were noted in 95% of the embryos. Possible mechanisms for BUdR‐induced malformations in the cardiovascular system of the chick are discussed.
Reduction of uterine blood flow by phenylephrine, an alpha‐adrenergic agonist, in the day 11 pregnant rat: Relationship to potentiation of acetazolamide teratogenesis
Authors: Ugen Kenneth E. , Scott William J.
Published: June 2005

We have demonstrated previously that phenylephrine, a selective postsynaptic alpha‐1‐adrenergic agonist, significantly potentiates the incidence of acetazolamide‐induced right forelimb ectrodactyly in a dose‐response manner. As reported herein, phenylephrine also decreases maternal uterine blood flow in a dose‐response manner as measured by radioactive microsphere methodology. At the potentiative dose of 12.5 mg/kg phenylephrine decreases uterine blood flow by 86.8% when compared to control. In turn, pretreatment with prazosin, a selective postsynaptic alpha‐1‐adrenergic antagonist, prevents this large decrease in uterine blood flow and abolishes the potentiation of acetazolamide teratogenesis by phenylephrine. Although the effects of acetazolamide or acetazolamide + phenylephrine on uterine blood flow were not measured the data suggest a correlation between decreased uterine blood flow and potentiation of acetazolamide teratogenesis.
Heat shock and thermotolerance during early rat embryo development
Authors: Walsh D. A. , Klein N. W. , Hightower L. E. , Edwards M. J.
Published: June 2005

Effects of heat shock on the development of early pre‐somite embryos have been studied using cultured rat embryos. The results illustrate the sensitivity of the developing head and brain to elevated temperatures prior to neural tube closure and the capacity of embryos to acquire thermotolerance. Embryos exposed briefly to an elevated temperature (43°C for 7.5 min) developed severe craniofacial defects including microphthalmia, microcephaly, gross reduction of the forebrain region, and open neural tubes. In contrast, a nonteratogenic heat shock (42°C for 10 min) caused embryos to acquire thermotolerance during a 15‐min recovery period at 38.5°C. Acquired thermotolerance was effective in protecting embryos from a subsequent more severe heat treatment which would have been teratogenic in an unprotected embryo. Recovering embryos mounted a heat shock response as evidenced by the induction of a 71 kilodalton heat shock protein. Activation of the heat shock response was not a teratogenic event in the developing embryo.
The role of maternal alcohol damage on ethanol teratogenicity in the rat
Authors: Sanchis R. , Sancho‐Tello M. , Chirivella M. , Guerri C.
Published: June 2005

To study the severity and degree of in utero alcohol effects in relation to the rate of maternal alcohol damage, multiparous 1‐year alcoholfed rats were used, with an appropriate pair‐fed control group. During pregnancy, alcoholic dams showed relatively high acetaldehyde levels (41 ± 19 μmol/1) and blood alcohol levels of 22.8 ± 14 mmol/1. They also showed marked histological alterations in liver as well as high serum aspartate‐aminotransferase, alanine‐aminotransferase, alkaline phosphatase, glutamate dehydrogenase, and gamma‐glutamyltransferase activities. The increase in serum enzyme levels did not correlate with an increase in hepatic enzyme levels since only glutamate dehydrogenase was enhanced in liver after 1 year of alcohol intake. In addition, except for an increase in low Km aldehyde dehydrogenase activity, there were no changes in liver alcohol metabolizing enzymes in chronic alcohol vs. pair‐fed females. Alcoholic rats showed a high incidence of damage in their progeny (resorptions, immature fetuses, decrease in fetal weight, etc.), and rats with the highest serum levels of the above enzymes (especially glutamate dehydrogenase and gamma‐glutamyl transferase) had severely affected progeny. Rats with minimal histological liver damage, in contrast, did not show resorptions. Thus, the results presented suggest that the stage of maternal alcohol illness, as indicated mainly by the extent of liver damage, plays an important role in the frequency and severity of in utero alcohol effects in the rat.
Epidemiology of bladder exstrophy and epispadias: A communication from the international clearinghouse for birth defects monitoring systems
Authors:   International Clearinghouse for Birth Defects Monitoring Systems
Published: June 2005

A study of infants with bladder exstrophy or epispadias was based on data from ten malformation monitoring systems around the world. The material is derived from nearly 6.3 million births. The recorded prevalence at birth of bladder exstrophy was 3.3 per 100,000 births and of epispadias (without bladder exstrophy) 2.4 per 100,000. The recorded rates of bladder exstrophy did not vary between the monitoring systems, but the rates of epispadias did. Furthermore, nearly all registered infants with epispadias were males. The sex ratio for bladder exstrophy was 1.5:1. Perinatal deaths occurred mainly when other malformations were also present. There was an increased risk in this group of malformations in infants of women aged‐less than 20 years. At high parity (3+), an increased risk was observed for bladder exstrophy, but there was a decreased risk for epispadias. The birth weight distribution was shifted slightly more to the left in isolated bladder exstrophy than in isolated epispadias, but was considerably shifted to the left when other malformations existed with bladder exstrophy. Most infants with other malformations belonged to the cloacal exstrophy sequence. There was no definite time trend between 1970 and 1985 in the prevalence at birth of bladder exstrophy. The study demonstrates how data from different monitoring registries can be pooled to characterize a rare malformation.
Potential teratogenicity of gonadotropin treatment for ovulation induction in the mouse offspring
Authors: Sakai Nobuyoshi , Endo Akira
Published: June 2005

The teratogenic effects of induced ovulation were studied in mice by using three different doses of pregnant mare's serum (PMS)/human chorionic gonadotropin (HCG) (2.5, 5, or 10 IU) at two different stages of the estrous cycle. The PMS/HCG treatment induced high incidences of external congenital anomalies in the offspring in a dose‐dependent manner. This was especially so when the treatment was “out of phase” to the naturally occurring ovulation schedule. The predominant malformations were open eyelids and cleft palate. The problems of extrapolating these findings to humans are discussed.
Comparative effects of retinoic acid and jervine on chondrocyte differentiation
Authors: Campbell Marlissa , Horton Walter , Keeler Richard
Published: June 2005

Jervine and retinoic acid are both teratogenic to structures which are initially modelled in cartilage. Differences in periods of maximal sensitivity, as well as in certain aspects of the morphological manifestations of exposure, indicate that these two teratogens act via different molecular mechanisms. Here we compare the effects of jervine and retinoic acid in three culture systems which represent sequential stages of the chondrocyte lineage. Proliferation of pluripotent C3H 10T 1/2 cells was decreased by exposure to jervine but was not affected by retinoic acid. Differentiation of high‐density “spot” cultures of embryonic limb bud mesenchyme were sensitive to both compounds. Mature chondrocytes were resistant to jervine but “dedifferentiated” after 48‐hour exposure to retinoic acid. We conclude that jervine compromises rapidly dividing chondrogenic precursors, whereas retinoic acid has little effect prior to the expression of cartilage‐specific proteins.
Epidemiological studies of neural tube defects in Newfoundland
Authors: Frecker M. , Fraser F. C.
Published: June 2005

A 9‐year survey of neural tube defects in Newfoundland showed (1) evidence for secular variation, with a peak in 1980, but no general downward trend as seen in some other populations; (2) significant geographic variation which did not correlate with hardness or nitrate content of the lake water; (3) a tendency for the proportion of females among anencephalic births to increase with increasing frequency of anencephaly among geographic regions. This supports previous evidence for a female‐specific contribution to the causes of increased liability to neural tube defect.
A comparison of incidence trends for esophageal atresia and tracheoesophageal fistula, and infectious disease
Authors: Fraser C. , Baird P. A. , Sadovnick A. D.
Published: June 2005

There has been a suggestion that esophageal atresia with tracheoesophageal fistula (EA/TEF) may be related to the occurrence of infectious disease in the population during the time of early gestation. There is therefore a need for further data on trends in incidence related to infectious diseases. Data on the occurrence of EA/TEF with and without additional congenital malformations may also be relevant. The British Columbia Health Surveillance Registry is population‐based with excellent case ascertainment of birth defects, and data are available on the incidence of infectious diseases for B.C., allowing comparison of trends to be made.

One hundred forty‐nine cases of EA/TEF occurred among 534,834 consecutive livebirths during the period 1966–1980 for an incidence rate of 1/3,590. No significant (p < 0.05) annual, seasonal or monthly incidence trends were observed. In addition, the occurrence of EA/TEF could not be correlated with the prior incidence of infectious hepatitis, rubella, salmonella, or rubeola.

Fifty‐five percent of individuals with EA/TEF had congenital malformations in other systems, most frequently cardiovascular, gastrointestinal, and genitourinary. Most individuals with additional congenital malformations had multiple system involvement.
Interlitter variability in fetal body weight in mouse offspring from continuous, overnight, and short‐period matings
Authors: Endo Akira , Watanabe Toshiaki
Published: June 2005

When female mice of the Jcl:ICR strain were mated with a male either (1) continuously throughout the day or (2) overnight or (3) during 2 hours in the morning at light period, the interlitter variability of fetal body weight on the 18th day of gestation was smallest in the group with short‐period mating. Thus, in the embryonic stage‐specific teratological experiments, this mating schedule is advised. Even for routine reproductive toxicity testing protocols, the short‐period mating may be preferable for the purpose of increasing test sensitivity.
Maternal cocaine use and genitourinary tract malformations
Authors: Chasnoff Ira J. , Chisum Gay M. , Kaplan William E.
Published: June 2005

A specific fetal disruption syndrome associated with maternal cocaine use has not as yet been documented. In the first 23 pregnancies evaluated in our program for chemically dependent women, one infant with prune belly syndrome and one infant with hypospadias were delivered to cocaine‐using women. In the present study, all infants delivered in our program received a renal ultrasound at 2–3 days of life. Fifty infants born to cocaine‐using women (group I) and 30 born to polydrug, noncocaine‐using women (group II) were evaluated. The two groups of women were similar for age, gravidity, and race. Mean birth weight of the infants in the two groups was similar. Seven infants in group I demonstrated genitourinary tract malformations while there were no infants with such malformations in group II. It is hypothesized that the vasoconstrictive effects of cocaine could explain the abnormalities of the genitourinary tract found in the cocaine‐exposed infants.
Postimplantation development of mitomycin C‐treated mouse blastocysts
Authors: Tam Patrick P. L.
Published: June 2005

Treatment of morula‐stage mouse embryos with mitomycin C (0.004–0.5 μg/ml) in vitro resulted in a decrease in the number of inner cell mass (ICM) cells at the blastocyst stage. The trophectoderm population was reduced only at the highest dosage (0.5 μg/ml) tested. Postblastocyst development in vitro was retarded: Fewer embryos formed trophoblastic outgrowth, and the ICM was poorly developed. The embryo transfer experiments demonstrated that a reduction in ICM cell numbers diminished the potential of embryogenesis. The presence of a sufficient number of trophoblasts and ICM cells in the blastocyst is therefore a prerequisite for successful implantation and embryogenesis. The mitomycin‐treated blastocysts with only 70% of normal ICM cells developed to egg cylinders that were about half normal size, but by days 12–14 the body size of the surviving embryo was similar to that of the control embryo. Morphogenesis was retarded during the early organogenesis stages, but only a slight delay was seen in the treated embryo on day 12. Such observation strongly suggests that a restorative phase of growth and morphogenesis has occurred during the immediate postimplantation period.
Hypoploidy and hyperplasia in the developing brain exposed to alcohol in utero
Authors: Alvarez Marvin R. , Stone David J.
Published: June 2005

Prenatal effects of acute maternal alcohol ingestion on chromosome segregation and mitotic frequency in the brain cells of the fetus were evaluated in mice by direct chromosome and mitotic counts and by flow cytometry. Fetuses were exposed to acute transplacental doses of alcohol for 4 days and killed on the fifth day. Those litters in which the fetuses were developed to the equivalent of normal 16th–17th‐day gestation age were analyzed. A marked increase in the number of hypoploid metaphases was observed in direct proportion to the dose ingested by the mother. An over 30% increase in hypoploidy over controls was measured in the fetuses exposed to the highest dose. Counts of mitotic cells showed an over tenfold increase in the mitotic index of the fetal brain exposed to alcohol. Flow cytometric measurements of DNA content in isolated fetal brain cell nuclei showed a shift from a single G0/G1 peak in controls to a bimodal G0/G1 – G2+M distribution in alcohol‐exposed fetuses of the same developmental age.
Aspirin exposure during the first 20 weeks of gestation and IQ at four years of age
Authors: Klebanoff Mark A. , Berendes Heinz W.
Published: June 2005

The relationship between maternal aspirin use during the first 20 weeks of pregnancy and the child's IQ at 4 years of age was investigated in 19,226 pregnancies occurring from 1959 to 1966 in the Collaborative Perinatal Project. The mean IQ of children exposed to aspirin was 98.3, which was 2.1 points higher (95% confidence interval = 1.7, 2.6; P < 0.0001) than that of unexposed children. Adjustment for multiple social, demographic, and other confounders reduced this difference to less than one point in favor of the aspirin exposed group, although statistical significance remained. Total days of exposure was used as an index of dose, and no dose‐response relationship between aspirin use and IQ was found. The effect of prenatal aspirin exposure did not vary by infant sex. It is concluded that an adverse effect of aspirin exposure on IQ is unlikely.
Role of myometrial constriction in the induction of wavy ribs in rat fetuses
Authors: Nakatsuka Toshio
Published: June 2005

Furosemide, a loop diuretic, was orally administered to pregnant Crj: CD (SD) rats at a dose of 300 mg/kg once on day 16 of gestation. Cartilage bone double staining of day 17 fetuses revealed a delay in ossification. Characteristic rib deformities were not seen until day 18 of gestation. Concomitant with this observation were reductions in the amount of amniotic fluid, compared to controls, on day 18 of gestation and thereafter. When isoxsuprine HCl (2 mg/kg, b.i.d.), a uterine muscle relaxant, was additionally injected ip to pregnant rats on days 17–19 of gestation, the incidence of wavy ribs was significantly (P ≤ .05) less than that seen after treatment with furosemide alone. These observations indicate that the myometrial constriction plays a significant role in the induction of furosemide‐induced wavy ribs.
The mouse teratogen dinocap has lower A/D ratios and is not teratogenic in the rat and hamster
Authors: Rogers John M. , Barbee Brenda , Burkhead Lesley M. , Rushin Elizabeth A. , Kavlock Robert J.
Published: June 2005

The fungicide dinocap is currently used in the control of powdery mildew. We have reported that dinocap is teratogenic in the CD‐1 mouse, causing cleft palate, otolith defects, and fetal weight deficits well below maternotoxic dose levels. In this study the maternal and fetal toxicity of dinocap was determined in the Sprague‐Dawley rat and Syrian golden hamster, and adult‐to‐developmental (A/D) toxicity ratios were calculated and compared with the previously established A/D ratio of dinocap in the mouse. Dinocap in corn oil was admisnistered by gavage to pregnant rats on gestation days 7–20 (0, 100, 150, 200 mg/kg/day) and to hamsters on gestation days 7–14 (0, 12.5, 25, 50, 75, 100, 200 mg/kg/day). Dams were killed on day 21 (rat) or day 15 (hamster), and litters were removed, counted, and weighed; half of each litter was necropsied for soft tissue defects, and the remaining half was processed for skeletal examination. In the rat, maternal extrauterine weight gain was significantly affected at 150 and 200 mg/kg/ day, relative liver weight was elevated at 100 mg/kg/day and above, and fetal weight was lower at 150 and 200 mg/kg/day. In the hamster, maternal extrauterine weight was lower at 12.5 mg/kg/day and above; fetal weight was reduced, and the incidence of dilated renal pelvis was higher, at 25 mg/kg/day and above. Thus the A/D ratios for dinocap in the rat and hamster are similar, approximately 1. Our previous studies have demonstrated that dinocap is teratogenic in the mouse, with an A/D ratio in the range of 8–16 in this species. The basis for the species‐specific teratogenicity and inconsistent A/D ratio of dinocap is unknown.
Split notochord syndrome with dorsal enteric fistula and sacral agenesis
Authors: Kramer Edward L. , Giacoia George P. , Say Burhan , Jarolim Kirby L. , Miller‐Hardy Dianne
Published: June 2005

Split notochord syndrome of the lumbosacral spine in association with dorsal enteric fistula is a rare phenomenon. To date, only nine human cases have been reported in the English literature. We present another case of this type, with sacral agenesis as an additional and unique finding. Several etiological theories are discussed including the persistence of the neurenteric canal, the occurrence of an ectopic or accessory neurenteric canal, a division or local redundancy of the notochord, an entodermal‐ectodermal adhesion, neural tube rupture caused by oversecretion of fluid, and failure or aberrancy of dorsal aortic distribution to the region of the neural folds resulting in prevention of timely neural tube closure.
Developmental toxicity of bropirimine in rats after oral administration
Authors: Marks Thomas A. , Poppe Susan M.
Published: June 2005

Timed‐pregnant Upj:TUC(SD)spf (Sprague‐Dawley) rats were orally (gastric intubation) dosed with bropirimine (an immunomodulator and inducer of interferon with antiviral and antitumor activities against experimental models) at 100, 200 or 400 mg/kg/day (first experiment), or at 25, 50, or 100 mg/kg/day (second experiment), on days 7–15 of gestation. In the first experiment, maternal toxicity occurred in all bropirimine‐treated groups as evidenced primarily by significant decreases in weight gain, as compared to the vehicle control group. Embryotoxicity also occurred as evidenced by a doserelated increase in the number of dams with early implantation sites only. This pronounced effect on early embryonic development led to an insufficient number of offspring to access the developmental toxicity of bropirimine. This effect and the fact that all three doses were toxic to the dams dictated that a second experiment be carried out at lower doses. Significant effects on maternal weight gain also were observed in the second experiment, at least in the first 4 days of dosing, although only one dam in the 100 mg/kg/day group had early implantation sites only, in contrast to 11 such dams at this dosage in the first experiment. However, the fact that there were significant dose‐related increases in the incidence of several variations in fetuses in this group indicated that there also was embryotoxicity at 100 mg/kg/day in the second experiment. Thus, although no biologically significant increases in the incidence of any malformation or major variation were found in this study, the results did indicate that bropirimine was embryotoxic at dosages which also produced significant maternal toxicity.
Corticosterone induction of cleft palate in mice dosed with orciprenaline sulfate
Authors: Iida Hiroshi , Kast Alexander , Tsunenari Yasuo , Asakura Makoto
Published: June 2005

Orciprenaline sulfate is a beta‐adrenoceptor stimulant chemically described as 1‐(3,5‐dihydroxyphenyl)‐1‐hydroxy‐2‐isopropylaminoethane sulfate (Alupent®). The drug has broncho‐dilating activity and has been developed in numerous countries since 1961. The purpose of these studies was to investigate the teratogenic potential of orciprenaline and its mode of action in pregnant Jcl:ICR mice, when administered during the period of organogenesis and, more systematically, during the critical period of palate formation. Daily doses of 5, 50, and 500 mg/kg were given orally by gavage to mice on days 6–15, 11–13, or on day 12 of gestation. Additional studies were done to evaluate the maternal cardiotoxic action of orciprenaline and its effects on adrenal cortex and endogenous serum corticosterone. Five mg/kg triamcin‐olone acetonide, a glucocorticoid, were given subcutaneously as a positive control causing 100% cleft palate. Myocardial necroses occurred in pregnant mice only after 500 mg/kg orciprenaline had been given, and a significant increase in cleft palate occurred if exposure took place during days 11–13 or day 12 of gestation. This increase in cleft palate can be explained by the teratogenic effect of an elevated maternal serum corticosterone level 1 hr after orciprenaline treatment, about three times the control value.
Case‐control study of hypospadias, based on registry informations
Authors: Källén Bengt
Published: June 2005

With the aid of data in the Swedish Medical Birth Registry for infants with hypospadias and controls, a number of variables were compared. Records of infants born in 1982–1983 (188 cases and 376 matched controls) contained information on involuntary infertility, previous spontaneous and induced abortions, use of oral contraceptives or a remaining IUD at conception, smoking in early pregnancy, occupation in early pregnancy, family situation, and diagnoses given during pregnancy and at delivery, including information on caesarean section and vacuum, extraction. Among all variables studied, only one group of statistically significant differences appeared: women whose sons had hypospadias more often than controls had a diagnosis of weak contractions, a higher rate of induced deliveries, and also a higher rate of caesarean sections. The finding of a higher caesarean section rate in infants with hypospadias was verified in a separate study of 1,736 hypospadic infants delivered in 1973–1981 and compared with all births in Sweden during that period. No difference in the rate of vacuum extractions was seen. This finding is interpreted as a result of an abnormality of the fetal‐placental‐maternal organism interaction, perhaps also disturbing the early pregnancy and increasing the risk for hypospadias.
Digit development and embryonic weight in mice: Analysis of sex‐related time difference and mating period‐related interlitter variability
Authors: Watanabe Toshiaki , Endo Akira
Published: June 2005

The embryonic growth and digit formation in limb buds were more advanced in male embryos than in female embryos at a specific time (day 12.0) of midgestation. Furthermore, when the number of digits was compared between the sexes according to their body weight, male embryos were found to be more advanced than females in the differentiation of the digit in limb buds. This is the first demonstration of the presence of a time difference in digit development between the sexes of mouse embryos. In the short‐period, morning‐mating group, embryonic weights at day 12.0 were lower than those in the overnight‐mating group. However, the digit' development was not very much delayed in proportion to the difference in body weights, and some “catch‐up” phenomena were observed in this group. Interlitter and intralitter variability in body weights of mouse embryos at day 12.0 was greater in the overnight‐mating group than in the short‐period‐mating group. These findings suggest that, in embryonic stage‐related teratological experiments in mice, a short‐period‐mating schedule is advised and that the incidence of developmental anomalies should be analyzed separately for male and female fetuses.
Interaction between the splotch mutation and retinoic acid in mouse neural tube defects in vitro
Authors: Kapron‐Brás Carolyn M. , Trasler Daphne G.
Published: June 2005

The interaction between the splotch gene (Sp) and all‐trans retinoic acid (RA) was investigated using cytogenetically marked Sp/ + and +/+ mouse embryos cultured in the presence of RA. Retinoic acid retarded the development of and had a teratogenic effect on mouse embryos in culture. In particular, RA had seemingly opposite effects on the posterior neural tube, inducing abnormally early fusion in some embryos and causing a dose‐dependent delay in others. When the effects of RA on identified Sp/+ and +/+ embryos were compared, the only observed difference in their responses was in the degree of the delay in posterior neuropore (PNP) closure. At the end of the culture period, among the untreated control embryos, the Sp heterozygotes showed retardation of PNP closure compared to +/+ embryos. In addition, the RA treatment was found to have induced a greater delay in posterior neural tube closure in Sp/+ than in +/+ embryos. The basis for this difference in response to RA is presumed to be the retardation of PNP closure that is caused by the Sp gene in heterozygous form. The effects of the gene and the teratogen are additive and the gene carriers thus have greater mean PNP lengths at the end of culture. Since the length of the PNP is an indication of an embryo's likelihood of developing spina bifida, this provides an explanation for the observation that Sp/+ embryos are more sensitive to the spina bifida‐causing effects of RA than are +/+ embryos.
Application of Y chromosomal repetitive sequences to sexing mouse embryos
Authors: Nishioka Yutaka
Published: June 2005

Identification of sex is often necessary to evaluate genetic or teratogenetic effects on embryonic development. A simple molecular technique to identify the sex of mouse embryos was studied using a Y chromosomal repetitive sequence (designated 145SC5). Since this technique does not require purification of DNA, it is particularly suitable for processing many embryos. Furthermore, 145SC5 detects 1% contamination of male DNA in a male–female DNA mixture. These results suggest that 145SC5 is a powerful molecular tool in a variety of studies on mouse development.
Teratogenic and postnatal developmental studies of morphine in Sprague‐Dawley rats
Authors: Fujinaga Masahiko , Mazze Richard I.
Published: June 2005

The teratogenic and postnatal developmental effects of morphine exposure during pregnancy were studied in Sprague‐Dawley rats in three separate experiments using chronically implanted osmotic minipumps in order to avoid respiratory depression. In the first experiment, the teratogenic effects of three different morphine dosages were studied: a low dose (10 mg/kg/day), an intermediate dose (35 mg/kg/day), and a high dose (70 mg/kg/ day). On day 5 of gestation, osmotic minipumps that deliver their contents at a constant rate for 15 days were implanted subcutaneously on the back of the rats. On day 20 of gestation, cesarean sections were performed, reproductive indices were determined, and fetuses were examined externally and then preserved for subsequent visceral and skeletal examinations. The pregnancy rate was significantly reduced at the intermediate and high doses to 57% and 6%, respectively (control, 83%). No teratogenic effects were observed at any dosage, but growth retardation was present in the intermediate‐dose group. In the second experiment, postnatal survival of the offspring of dams treated with either normal saline, morphine (35 mg/kg/day); or the synthetic opioid, fentanyl (500 μg/kg/day) were studied. Offspring of morphine‐treated dams had a significantly higher mortality rate, which peaked at 56% within 2 days. No effect was seen after fentanyl treatment. In the third experiment, pups of morphine‐treated dams were cross‐fostered by saline‐treated dams; the postnatal mortality in offspring of morphine‐treated dams remained high (62%). Our results indicate that doses of morphine up to 35 mg/kg/day delivered by osmotic minipumps are not teratogenic in rats but cause other adverse fetal effects that result in increased postnatal mortality.
Cardiovascular anomalies produced by nimustine hydrochloride in the rat fetus
Authors: Miyagawa Sachiko , Ando Masahiko , Takao Atsuyoshi
Published: June 2005

The cardiovascular teratogenicity of nimustine hydrochloride (ACNU) was studied in rat fetuses. This drug is a nitrosourea derivative anticancer agent and produces alkylation of DNA. Pregnant Donryu rats were treated with single doses of 10, 11 or 13 mg/kg of the teratogen at various stages during gestation. Examination of the hearts was performed by microdissection after sacrificing the animals on the 20th day of gestation. The highest frequency of cardiovascular anomalies was found in the groups treated on the 8th day of gestation, but there was no difference in the rates induced by the three dosages of ACNU administered. The most common cardiovascular anomalies observed were ventricular septal defect (76.8%) and double outlet right ventricle (10.3%). A considerable number of affected fetuses (37/263) showed complex cardiac anomalies with atrioventricular (AV) malalignment and other AV valve anomalies. These anomalies include: double inlet left ventricle, straddling AV valve, atresia or stenosis of the AV valve, and dysplastic AV valve. ACNU appears to be a useful teratogenic agent for inducing complexes of cardiac anomalies which include AV malalignment.
Recombinants in the H‐2S/H‐2D interval of mouse chromosome 17 define the map position of a gene for cleft palate susceptibility
Authors: Gasser David L. , Yadvish Karen N. , Trammell Michele A. , Goldman Allen S.
Published: June 2005

The H‐2 region of mouse chromosome 17 is known to include one or more genes that affect susceptibility to cortisone‐induced cleft palate. We have now studied congenic strains that possess crossovers in the interval between H‐2S and H‐2D and have observed significant differences in susceptibility among recombinants that had been believed to possess the same H‐2 haplotypes. Pregnant mice were injected on days 11 through 14 of gestation with 100 mg of cortisone per kg of body weight. The frequency of cleft palate in B10.A(2R) was significantly greater than in B10.A(1R), despite the fact that both have H‐2a/H‐2b crossovers in the interval between the S and D loci and have the same alleles at all loci that have been previously characterized. Both B10.BAR5 and B10.BAR12 were significantly more susceptible than B10.A(18R), although these strains also share the same alleles at all loci that have been previously characterized. All three of these strains have H‐2b/H‐2a recombinant chromosomes, with crossovers in the S/D interval. Genetic linkage between H‐2 and the high‐susceptibility gene of B10.BAR5 was confirmed by testing H‐2 homozygotes derived by intercrossing backcross animals. These data therefore suggest that a gene coding for susceptibility, which we designate Cps‐1, maps in the 350‐kb interval between H‐2S and H‐2D, and the congenic strains that we have found to be different have different crossover points within this interval. Alleles at the Cps‐1 locus have embryonic effects, but no demónstrable effects on the maternal environment.
Central nervous system malformations induced by triamcinolone acetonide in nonhuman primates: Pathology
Authors: Tarara R. P. , Cordy D. R. , Hendrickx A. G.
Published: June 2005

Triamcinolone acetonide (TAC) was administered to pregnant macaques (Macaca mulatta [15] and M. radiata [7]) during gestational days (GD) 23 to 41 using various dosing schedules. A daily dose of 10 mg/kg is ≅ 100 × the human dose equivalent. The brains of the fetuses and infants were studied grossly and histologically. All cases displayed either the mild form of the TAC‐induced syndrome (craniofacial dysmorphia, cranium bifidum occultum, meningocele, and mild distortion of the midbrain) or the more severe form (occipital encephalocele, hydrocephalus, severe distortion of the midbrain or midbrain “beaking,” shunting of cerebrospinal fluid, and craniofacial malformations). The dysmorphology was dose‐related, with severity increasing at higher doses or with increased numbers of treatments. Individual cases were assessed for the severity of the syndrome by comparison of like components between groups. The lesions observed were morphologically comparable to those described in spontaneous human cases; the TAC‐induced occipital encephaloceles were associated with brainstem and cerebellar abnormalities, and, with the less severe form of the syndrome, brainstem abnormalities were occasionally present, with occipital meningoceles. Controversy exists concerning the significance and temporal development of the midbrain changes. However, the associated alteration in aqueduct conformation may have been responsible for functional compromise and ensuing hydrocephalus.
Effects of eflornithine hydrochloride (DFMO) on fetal development in rats and rabbits
Authors: O'Toole Barbara A. , Huffman Kenneth W. , Gibson John P.
Published: June 2005

Eflornithine hydrochloride (DFMO) is a highly selective, enzyme‐activated, irreversible inhibitor of the enzyme L‐ornithine decarboxylase (ODC). Because of its role in the biosynthetic pathway of polyamines, ODC is essential for the growth and development of newly implanted embryonic tissue. In order to assess its effect on embryonic growth and fetal development, at various stages of gestation, DFMO was administered in the drinking water to pregnant rats and rabbits at several concentrations (from 0.03% to 3.0%) and times (from days 7, 10, or 11 through days 18 or 19). Rats were killed on day 21 and rabbits on day 29 of pregnancy (day 1 = day of insemination), and the implantations and fetuses were examined. At a concentration of 1.0% (approximately 1,270 mg/kg/day) in rats and 3.0% (approximately 915 mg/kg/day) in rabbits, maternal food and water consumption and body weight gain were significantly reduced during the treatment period, and all implantations were aborted or resorbed. At lower doses (approximately 200–600 mg/kg/day) fetuses survived to term, though in reduced numbers, and a marked reduction in average fetal weight was seen. At levels of 60 mg/kg/day or lower, there were no deleterious effects to the dams or their offspring. Few malformations were detected at any dose level by gross teratologic examination; nor were any considered to have been drug induced because of their sporadic incidence. The embryotoxicity and severe growth retardation demonstrated by these studies verify that adequate polyamine levels are essential for normal embryonic and fetal development.
Limb reduction defects in over one million consecutive livebirths
Authors: Froster‐Iskenius Ursula G. , Baird Patricia A.
Published: June 2005

Limb reduction defects occurring among 1,213,913 consecutive livebirths in British Columbia during the period 1952–1984 inclusive were reviewed. A total of 659 cases of limb reduction defects were identified, 393 of them involving the long bones and 190 of them more than one limb. The time period 1966–1984, during which ascertainment was consistent, was evaluated, and an incidence of 5.97 per 10,000 livebirths (1 in 1,692 live births) was found. The data were evaluated for trends over time, sex ratio, and regional and ethnic distribution. Associated anomalies of other organ systems in these cases were analyzed, and overall about one‐half of the cases have additional defects. The majority of these additional defects affect the musculoskeletal system and include such entities as clubfoot, hip dislocation, and congenital contractures. Defects are also frequent in other organ systems, such as the cardiovascular, gastrointestinal, and genitourinary systems. By far the most common limb defects are terminal longitudinal defects then terminal transverse defects. Of all cases of limb defects, 75% are upper limb and 25% lower limb. We found no evidence that one side is affected more frequently.

About 6.5% of cases had another family member registered with a skeletal defect; 12.9% of cases died within the first year of life, the majority (85%) of those dying having additional defects. Etiological considerations are discussed for some subgroups. A classification system for limb defects suitable for use by registries using the World Health Organization (WHO) International Classification Disease (ICD) 9th Revision is described.
Hemodynamic effects of acetylcholine in the chick embryo and differences from those in the rat embryo
Authors: Md Makoto Nakazawa , Ohno Takashi , Miyagawa Sachiko , Takao Atsuyoshi
Published: June 2005

It has been reported that acetylcholine induces cardiac anomalies in the chick embryo. Thus, we studied hemodynamic effects of this drug in the chick embryo and also compared them with those in the rat embryo since we found that the effect of caffeine was different between the chick and rat embryos. Acetylcholine was given at doses of 5, 0.5, and 0.05 μg into the vitelline vein in chick embryos at Hamburger–Hamilton stage 21 and at a dose of 0.5 μg into the placenta in rat embryos at gestational day 12. In the chick embryo, heart rate was reduced to 91, 88, and 87% of control at the end of injection of 0.05, 0.5, and 5 μg, respectively, then returned to the baseline level. Vitelline arterial blood pressure was 110% of control with 0.05 μg, 134% with 0.5 μg, and 142% with 5 μg at 1 min after injection. The dorsal aortic blood flow decreased with time after injection, but it was increased only by a 5 μg dose at the end of injection. The vascular resistance increased in a dose‐dependent manner. In the rat embryo, the change of heart rate was qualitatively similar to that of the chick embryo. The blood pressure did not change significantly. The blood flow velocity at the outflow tract decreased at the end of injection, which indicated the decrease in cardiac output, along with slowing of heart rate, then returned to the control level thereafter. We conclude that acetylcholine has a vasoconstrictive effect at this stage of the chick embryo and its teratogenicity may not be explained by an hemodynamic effect based on a one‐to‐one relation of cause and effect and that there is species difference in hemodynamic effects but significance of this result is to be clarified.
In vitro developmental toxicity of five direct‐acting alkylating agents in rodent embryos: Structure‐activity patterns
Authors: Faustman Elaine M. , Kirby Zamyat , Gage Daniel , Varnum Michael
Published: June 2005

Five direct‐acting alkylating agents were examined qualitatively and quantitatively for their ability to produce developmental toxicity in rodent postimplantation embryos. These agents were structurally related and were capable of donating either a methyl (methylnitrosourea, MNU; methylnitronitrosoguanidine, MNNG; methyl methanesulfonate, MMS) or ethyl (ethylnitrosourea, ENU; ethyl methanesulfonate, EMS) group to nucleophiles. These agents' reactivities were known to differ. In day 10 rat embryos in vitro a single, 2‐hour exposure was shown to be sufficient to elicit dose‐dependent increases in embryo lethality and malformations. Qualitatively, the patterns of embryo malformations reported in treated embryos paralleled those observed in in vivo studies, especially in regard to adverse effects on central nervous system and craniofacial systems. Quantitatively, the order of potency of these agents in vitro was: MNNG > MNU > ENU > MMS > EMS. In vivo studies reported a different order of potency. In vitro, methylating agents were consistently more potent than ethylating agents. Other chemical properties such as nucleophilic reactivity or half‐life under physiological conditions could not explain observed potency relationships. Future investigation of other chemical properties of these agents such as specific alkylation and carbamylation reactivities may expand these intial structure‐activity observations.
Perspectives on holoprosencephaly: Part I. Epidemiology, genetics, and syndromology
Authors: Cohen M. Michael
Published: June 2005

This paper provides an updated, comprehensive, critical review of the epidemiology, genetics, and syndromic aspects of holoprosencephaly and is divided into four parts. In the first part, epidemiologica aspects are discussed under the following headings: prevalence, temporal trends, socioeconomic status, exposure to environmental teratogens, maternal and paternal ages, pregnancy histories, and birth weights. The second part analyzes the facial phenotypes because the genetic and syndromic aspects of holoprosencephaly cannot be understood without knowledge of facial variability and its meaning. Topics discussed include cyclopia, ethmocephaly, cebocephaly, median cleft lip, and less severe facial dysmorphism. The third section, on genetics, analyzes associated anomalies, chromosomal and nonchromosomal holoprosencephaly, family studies, twin studies, genetics of nonsyndromic holoprosencephaly, and recurrence risks. The final section on syndromology summarizes 48 conditions in which some degree of holoprosencephaly may be a feature.
Regulation of the inducible heat shock 71 genes in early neural development of cultured rat embryos
Authors: Walsh D. A. , Li K. , Speirs J. , Crowther C. E. , Edwards M. J.
Published: June 2005

Activation of the inducible heat shock 71 genes and their role in the heat shock response was studied in vitro in 9.5 day‐old rat embryos at neural tube closure. The transcriptional response of a 71 kilodalton (kD) heat shock gene induced after various regimes of heat shock and acquired thermotolerance was investigated. Expression and accumulation of the heat shock (hs) 71 mRNA in the neuroectoderm was studied by Northern and dot blot analysis. Specific expression in various cell types and regions of the neuroectoderm were examined by in situ hybridization.

Exposure of embryos to a heat shock at 43°C for 7.5 min caused high levels of hs mRNA 71 accumulation in the neuroectoderm, pronounced protein synthesis inhibition, and regulated recovery. Specific neuroectoderm cell death followed, resulting in major developmental defects of the eye and forebrain region. A mild heat shock of 42°C for 10 min induced the heat shock response, hsp synthesis, and cell recovery, but produced no cell death or deformities. Preheating the embryo at 42°C resulted in acquired thermotolerance to an otherwise teratogenic 43°C heat shock. Thermotolerance was associated with a rapid recovery of protein synthesis associated with hs 71 mRNA expression. Dot blot analysis showed that after a 42°C heat shock, 71 mRNA was rapidly transcribed and transported into the cytoplasm where it was degraded within 2 hr of the initial response. The results suggest that the heat shock protein (hsp) 71 gene may have a protective rather than a rescuing function.