bluuebunny/crossref_metadata_2025 huggingface dataset:
Teratogenicity and embryolethality of acrolein and structurally related compounds in rats
Authors: Slott Valerie L. , Hales Barbara F.
Published: June 2005

Acrolein, a metabolite of the anticancer agent cyclophosphamide, is teratogenic to rats after intraamniotic administration. It is not known whether acrolein or a metabolite of acrolein is responsible for the teratogenicity of this compound. We assessed the teratogenicity and embryolethality of acrolein and five structurally related compounds: acrylic acid, allyl alcohol, glycidol, glyceraldehyde, and propionaldehyde by intraamniotic injections in Sprague‐Dawley rats on day 13 of gestation. All compounds tested were significantly embryolethal with at least one concentration of the drug. Acrolein was the most embryolethal of the drugs, causing a significant increase in resorptions with as little as 0.1 μg/fetus; the other drugs were embryolethal at doses 100–10,000 times that of acrolein. Acrolein was also the most teratogenic of the drugs tested; a dose as low as 5 μg/fetus caused a significant increase in the incidence of fetal malformations. Of the other compounds tested, only glycidol at a dose of 1,000 μg/fetus induced a significant number of malformed fetuses compared to control. These results suggest that it is acrolein itself that is responsible for its teratogenicity.
Effects of dexamethasone on phospholipase activities in palate mesenchyme cells in vitro
Authors: Chepenik K. P. , George M. , Greene R. M.
Published: June 2005

Treatment of primary cultures of palate mesenchyme cells from AJAX strain embryos with dexamethasone inhibited only phospholipase activity expressed at pH 7.5. A similar treatment did not have such an effect on palate mesenchyme cells from C57BL/6J strain embryos. Since the AJAX strain embryo is sensitive to the induction of cleft palate by exogenous glucocorticoids and the C57BL/6J strain is less so, these data allow consideration of phospholipase activity as a site of regulation for development of the palate.
Cardiovascular system in conjoined twins: An analysis of 14 Korean cases
Authors: Seo Jeong Wook , Shin Sung Sik , Chi Je Geun
Published: June 2005

A new classification of cardiovascular system in conjoined twins is introduced. A special effort has been made to analyze the degree of fusion and symmetry of hearts and great vessels, based on 14 pairs of conjoined twins. The degree of cardiovascular union of the twins is classified into five types. Cases with no vascular union in cardiac, aortic, and inferior vena caval levels were grouped into type I (four cases). Cases with separate hearts and union between aortas or inferior venae cavae were grouped into type II (three cases). Cardiac fusion at the atrial level was grouped into type III (three cases). All of the three cases showed fusion between right atria (subtype IIIa). The theoretical fusion between the left atria or between the left and right atria is put into subtype IIIb. The type IV represents fusion of both atria and ventricles regardless of the number of the chambers (three cases). Type V represents single heart in one of the twins (one case). The external morphologic type and the situs of each twin pair were closely related to the cardiac abnormalities. Dicephalus and thoracopagus were more likely to be associated with abnormal situs and complex cardiac fusion. Abnormal situs was seen in seven out of 14 cases. Three cases with polysplenia and a case with asplenia showed more complex cardiac abnormalities than those with normal situs or situs inversus.
Evaluation of Bendectin embryotoxicity in nonhuman primates: II. Double‐blind study in term cynomolgus monkeys
Authors: Hendrickx A. G. , Cukierski M. , Prahalada S. , Janos G. , Booher S. , Nyland T.
Published: June 2005

The embryotoxic and teratogenic potential of Bendectin was assessed in this double‐blind study in the cynomolgus monkey (Macaca fascicularis). Bendectin was administered orally at doses approximately two, five, and 20 times the human dose equivalent from 22 ± 2 through 50 days of gestation. Fetuses were delivered by cesarean section near term and examined for malformations. There was no maternal toxicity as evidenced by maternal weights and physical signs. There was no correlation between dosage and the number of prenatal deaths. No significant abnormalities related to treatment were observed in postdelivery physical examinations, placental evaluations, external and internal gross examinations, or from radiographs of the neonates. Under the conditions of this study the treatment of pregnant cynomolgus monkeys with Bendectin produced no evidence of teratogenicity or embryo‐, or fetal‐, or maternal toxicity.
Early biochemical detection of adverse effects of a neurobehavioral teratogen: Influence of prenatal methylmercury exposure on ornithine decarboxylase in brain and other tissues of fetal and neonatal rat
Authors: Slotkin Theodore A. , Pachman Steven , Kavlock Robert J. , Bartolome Jorge
Published: June 2005

Ornithine decarboxylase (ODC), an enzymatic regulator of macromolecule synthesis, has proven useful as a biochemical marker for teratologic events. Daily administration of methylmercy (0.5 or 1 mg/kg s.c.) to pregnant rats during the second and third trimesters had a profound effect on ODC in whole fetus that was detectable as early as 13 days of gestation. Levels of enzyme activity in fetal brain also showed a marked increase centered about gestational day 17 as well as a significant elevation during early postnatal life; in the latter case, the cerebellum appeared to be a major target for methylmercury‐induced aberrations. These effects were accompanied by little or no alteration in general growth rate, brain weights, or weights of other tissues (liver, heart, lung). Furthermore, no other tissue displayed such dramatic effects on ODC activity. Lowering the dose of methylmercury by an order of magnitude (0.05 to 0.1 mg/kg), levels which are associated with almost purely neurobehavioral effects of the teratogen, still resulted in clear‐cut elevations of both whole fetus ODC and fetal and neonatal brain ODC. These results indicate that a sensitive biochemical detection procedure used in the fetus/neonate can successfully predict the subsequent tissue‐specific damage to neurotransmitter systems and behavior resulting from methylmercury.
The effect of prenatal procarbazine treatment on brain development in the rat
Authors: Johnson J. M. , Thompson D. J. , Haggerty G. C. , Dyke I. L. , Lower C. E.
Published: June 2005

Groups of pregnant Sprague‐Dawley rats were treated orally with procarbazine, an antineoplastic drug, at dose levels of 0, 1.0, 2.5, 5.0, 7.5, and 10.0 mg/kg/day from days 12 through 15 of gestation. Following normal delivery, offspring were raised until day 21 and sacrificed, and their brains removed and weighed. A dose‐dependent micrencephaly, characterized by hypoplasia of the cerebral hemispheres, was seen starting at 2.5 mg/kg/day. In a second study, groups of pregnant female rats were given a single dose of 10 mg/kg procarbazine on gestation day 12, 13, 14, or 15. Micrencephaly occurred in 21‐day‐old offspring from all groups, with the greatest effect induced on days 13, 14 and 15. Analysis of brain region weights revealed a maximum reduction in neocortex weight in offspring from groups treated on days 13 and 14. The hippocampus, cerebellum, and diencephalon‐midbrain were also reduced in size, depending on the day of treatment, while the corpus striatum and ponsmedulla were spared. In a final study, embryos from females treated on gestation days 12 through 15 were removed, fixed, and sectioned at 24‐hour intervals starting on gestation day 13. Necrosis and cellular degeneration were observed with decreasing severity in the telencephalon, diencephalon, mesencephalon, and medulla. The neocortex of 20‐day treated fetuses was characterized by a thickening of the ventricular zone and reduced cellularity of the cortical plate.
Developmental and cytogenetic effects of caffeine on mouse blastocysts, alone or in combination with benzo(a)pyrene
Authors: Spindle Akiko , Wu Kitty
Published: June 2005

Mouse blastocysts were treated with caffeine and/or benzo(a)pyrene (BP), and the effects on development and on induction of sister chromatid exchanges (SCEs) were examined. Caffeine interfered with blastocyst development in a dose‐related manner. At 4 mM, the highest concentration tested, caffeine interfered with development of blastocysts to all four endpoints: hatching, trophoblast outgrowth, inner cell mass (ICM) growth, and two‐layer (primary endoderm and ectoderm) differentiation of ICMs. At 2 mM, caffeine reduced the incidence of both ICM growth and differentiation but did not affect hatching or formation of trophoblast outgrowths. At 1 mM, caffeine interfered only with ICM differentiation. Cell proliferation was least sensitive to caffeine and was reduced at concentrations of ≥2 mM. Induction of SCEs was most sensitive to caffeine exposure; an increase in SCE frequency was observed at 0.1 and 0.5 mM. When caffeine was added to cultures with BP (1 μM, a concentration that was not embryotoxic and did not induce SCEs), both embryotoxic effects and SCE frequency were increased. The enhancing effect on SCE induction was particularly marked; as little as 0.1 mM caffeine was sufficient to cause doubling of induced SCE frequencies when added to cultures with BP.
The embryotoxicity of gossypol
Authors: Beaudoin Allan R.
Published: June 2005

In utero development was analyzed in pregnancies that resulted from matings between gossypol‐treated male rats and untreated female rats and in pregnancies in which gossypol was administered to the pregnant rat only. Gossypol treatment of males had no effect on the outcome of pregnancy. There was no significant effect on resorption, fetal growth, or malformation rate. Similarly, gossypol administered to pregnant dams at stages during organogenesis had no observable effect on pregnancy. Under the conditions of this experiment, gossypol administered to either the breeding male rat or the pregnant female rat had no demonstrable adverse effect on development in utero.
The effects of L‐ and D‐carnitine administration on cardiovascular development of the chick embryo
Authors: Kargas Steve A. , Gilbert Enid F. , Bruyere Harold J. , Shug Austin L.
Published: June 2005

A single 1.0‐ml volume of L‐ or D‐carnitine solution, at several selected mmole concentrations, was applied to the extraembryonic membranes of 3‐ and 4‐day chick embryos in ovo. Hamburger‐Hamilton stages of chick development ranged from 17 to 23. During the 17–18th days of incubation, embryos were dissected, and both survival and intracardiac anomaly rates were determined. Only at extremely high doses, both stereoisomers of carnitine exhibited a statistically significant toxigenic effect (p < 0.001) as measured by a sharp decrease in survival rate when compared to chick Ringer's saline controls. Furthermore, since the anomaly rates became significant only near the LD50's, this indicated that intracardiac anomalies were induced only at toxic doses. Therefore, it is suggested that cardiovascular teratogenicity may be the result of toxicity. Below the LD50, anomaly rates were not significantly different from those of control embryos. In comparison, L‐ and D‐carnitine were significantly different from one another (p < 0.001) both in survival rate and percent affected embryos at a dose of 0.5 mmole. In summary, exogenous carnitine administration to the chick embryo does not appear to be deleterious to the developing cardiovascular system.
The effect of oxygen concentration on the teratogenicity of salicylate, niridazole, cyclophosphamide, and phosphoramide mustard in rat embryos in vitro
Authors: Greenaway J. C. , Mirkes P. E. , Walker E. A. , Juchau M. R. , Shepard T. H. , Fantel A. G.
Published: June 2005

Comparisons were made of rat embryos cultured at 5% or 20% oxygen in the presence of salicylate (SAL), cyclophosphamide (CP), niridazole (NDZ), or phosphoramide mustard (PM). Multiple regression analyses were used to compare the effects of drug concentration, oxygen concentration, and the product of drug times oxygen concentration on malformation incidence, viability, and protein content of embryos cultured for 24 hours. Drug concentration significantly affected malformation incidence or severity and protein content (P < 0.001) for the four drugs tested. Oxygen concentration significantly affected protein content for the four compounds (P < 0.001) but affected malformation incidence only with NDZ. Furthermore, the interaction of oxygen concentration and drug concentration significantly affected the malformation incidence in the presence of NDZ (P < 0.001), and protein content (P < 0.001) and viability (P < 0.001) in the presence of CP.

The pattern of significant effects of the independent variables (drug concentration, oxygen concentration, and drug times oxygen concentration) is consistent with the hypotheses of oxygen‐dependent metabolism (or lack of metabolism) of the drugs in question. NDZ, which is thought to be converted to reactive intermediates by an oxygen‐inhibited nitroreductase, was more toxic at reduced oxygen tension. CP, which is activated by an oxygen‐dependent P‐450 system, was more toxic with increased oxygen tension. Significant effects of the independent variables on embryos exposed to SAL or PM were consistent with the effects on control embryos, notably, increased protein content with increased oxygen.
Morphology of early fetal deaths and their chromosomal characteristics
Authors: Byrne Julianne , Warburton Dorothy , Kline Jennie , Blanc William , Stein Zena
Published: June 2005

The morphologic features of a consecutive series of 3,472 singleton spontaneous abortions are described. Of the total, 21% consisted of wellformed fetuses (over 30 mm long), 27.9% had no identifiable fetal tissues, 34.2% consisted of fetal membranes only, and the remainder, 16.8%, consisted of a variety of embryonic types. The rate of focal malformations among embryos over 10 mm in length and among fetuses was 16.4%. The overall rate of chromosome anomalies in the 1,356 karyotyped specimens was 39.8%. The vast majority, 94%, occurred in embryos less than 30 mm, and in specimens whose development had not proceeded beyond differentiation of fetal membranes. The rate of chromosome anomalies among nonmalformed fetuses (greater than 30 mm) was only 1.7%. However, the presence of limited embryonic development was not a good predictor of the presence of a chromosome anomaly. Slightly over half (56%) of all specimens less than 30 mm long had chromosome anomalies; for individual classes of such specimens the rate ranged from 45% to 81%. The morphologic category with the highest rate of karyotypic anomalies had an excess of monosomy X abortuses. A gradient of developmental level could be associated with the degree of intrauterine mortality of each chromosome anomaly; i.e., conceptuses with karyotypes that occur at term had a greater degree of embryonic development than karyotypes that are never seen among term births. Thus, trisomies 13, 18, and 21 were more often associated with fetuses, and less often with tissue fragments than other trisomies. Focal malformations were multiple and severe in abortuses with triploidy, trisomies 13 and 18, and monosomy X and mild in trisomy 21. With the exception of monosomy X the malformations were similar to, and not more severe than those reported from, term births with the same anomaly. The high rate of intrauterine mortality in conceptuses with chromosome anomalies could be ascribed to their failure to develop past the embryonic stages. However, the presence of an equally large fraction of chromosomally normal abortions with the same degree of rudimentary development suggests the existence of early and profound developmental problems that are not associated with anomalies of the chromosome complement.
The effect of graded hypoxia on the embryonic chick heart
Authors: Ruckman Roger N. , Rosenquist Glenn C. , Rademaker Deborah A. , Morse Dennis E. , Getson Pamela R.
Published: June 2005

Embryonic ventricular function in the chick was measured in response to graded levels of hypoxia. Myocardial contractility, as measured by cinephotoanalysis and expressed as shortening fraction, was significantly depressed after 1 hour of moderate hypoxia (6% O2) and after 5 hours of milder (16% O2 and 11% O2) levels of hypoxia (P < .05). Microscopy confirmed associated myocyte damage with cell death noted after 5 hours of moderate hypoxic stress. Heart rate change was not related to the severity of hypoxia. The greatest level of tachycardia was noted with conditions of mildest hypoxia (16% O2). The data confirm that cardiac contractility, as measured by shortening fraction, is depressed on exposure to hypoxia, with impairment of function related to the severity of the hypoxic conditions.
Transfer of valproic acid and its main active unsaturated metabolite to the gestational tissue: Correlation with neural tube defect formation in the mouse
Authors: Nau Heinz
Published: June 2005

The pharmacokinetics of the antiepileptic drug valproic acid (2‐proply‐pentanoic acid; VPA) and its main active metabolite 2‐en‐VPA (2‐propyl‐2‐pentenoic acid) in mouse serum and gestational material were studied and correlated with the drastic differences between the two compounds in their embryotoxicity. The peak levels of VPA reached after 0.5 hours were only slightly higher than that of 2‐en‐VPA (both in mother and gestational material). The free concentrations of VPA and 2‐en‐VPA in maternal serum also peaked at 0.5 hours. After that time the free maternal serum levels of 2‐en‐VPA decreased much more rapidly than the concentrations in the gestational materials. The area under the concentration/time curves (AUC) values of 2‐en‐VPA in mother and embryo were lower than corresponding values of VPA; the higher clearance of 2‐en‐VPA was predominantly due to an increased volume of distribution. Since we have previously shown that the peak concentrations and not the AUC values of VPA correlated with the teratogenicity of this compound, our present data indicate that the low teratogenic and embryotoxic potential of 2‐en‐VPA is a result of the intrinsic activity of this compound and not of lower peak concentrations reached in mother and embryo.
Synergistic interaction of 2,3,7,8,‐tetrachlorodibenzo‐p‐dioxin and hydrocortisone in the induction of cleft palate in mice
Authors: Birnbaum L. S. , Harris M. W. , Miller C. P. , Pratt R. M. , Lamb J. C.
Published: June 2005

Glucocorticoids cause cleft palate in sensitive mouse strains by interfering with the proliferation of mesenchymal cells in the palatal shelves; 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin (TCDD) also causes cleft palate, but its effects involve the epithelial cells. The purpose of this study was to examine the interaction of TCDD and the glucocorticoid hydrocortisone in the induction of malformations. Pregnant C57BL/6N mice were treated on gestation days 10–13 with TCDD (0 or 3 μg/kg, p.o.), hydrocortisone (0, 25, 50, or 100 mg/kg, s.c.) or a combination of TCDD and hydrocortisone. The dams were killed on gestation day 18 and the mice were analyzed for maternal and fetal toxicity and soft tissue malformations. TCDD alone had no effect on litter size, fetal weight or viability, or maternal weight gain. This dose of TCDD is essentially a threshold dose and it did not produce cleft palate in this study, but all the TCDD‐treated fetuses had hydronephrosis, the most sensitive indicator of TCDD teratogenicity. Hydrocortisone alone caused dose‐related decreases in fetal weight and maternal liver/body weight ratios, and dose‐related increases in cleft palate (0, 5, 10, and 30%). No effects of hydrocortisone were detected on litter size or fetal viability, but maternal weights were affected. Combination of all doses of hydrocortisone with TCDD resulted in a 100% incidence of cleft palate, accompanied by a decrease in litter size and fetal weight and an increase in fetal mortality related to the dose of hydrocortisone. TCDD tended to reverse the decrease in liver/body weight ratio seen with hydrocortisone alone. Morphological assessment of the palatal shelves late on gestation day 14 revealed that the embryos exposed to both TCDD and hydrocortisone resembled hydrocortisone alone. The synergism observed between these two teratogens may be due to changes in the receptors which mediate sensitivity to the induction of cleft palate.
Pharmacological studies on the potentiation of phenytoin teratogenicity by acetaminophen
Authors: Lum Joseph T. , Wells Peter G.
Published: June 2005

An in vivo murine model was developed to measure maternal phenytoin biotransformation along with the covalent binding of phenytoin to fetal tissues in the same fetuses which were assessed for fetal anomalies. Acetaminophen was administered to pregnant CD‐1 mice 1 hour prior to phenytoin, both given i.p. at varying doses and gestational times between days 11 and 13. Dams were killed between days 12 and 19. Metabolites reflecting the enzymatic bioactivation of phenytoin were quantified in maternal plasma and urine with high‐performance liquid chromatography (HPLC). Acetaminophen pretreatment caused a threefold increase in phenytoin‐induced fetal cleft palates without increasing resorptions. The covalent binding of radiolabeled phenytoin to fetal and placental tissues measured on day 13 was increased twofold and threefold, respectively, by acetaminophen pretreatment. Phenytoin covalent binding measured on day 16 was significantly increased in the livers of fetuses with cleft palates, but not in the livers of dams with fetuses having cleft palates. Binding to fetal brain on day 16 was over fourfold higher than that in maternal brain. Acetaminophen pretreatment differentiated dams into poor and extensive metabolisers of phenytoin, with only the latter group carrying fetuses with cleft palates. The incidence of fetal cleft palates correlated positively with maternal urinary levels of phenytoin (r = + .81, P < .01) and its dihydrodiol metabolite (r = + .61, 0.05 < P < .1), and negatively with levels of para‐hydroxylated phenytoin (r = −.85, P < .01). These findings related both to the mechanism of phenytoin teratogenicity and its potentiation by acetaminophen.
Acetazolamide does not disrupt limb regenerate morphogenesis in the salamander, Plethodon cinereus
Authors: Dinsmore Charles E. , Maren Thomas H.
Published: June 2005

Acetazolamide, a potent and highly specific inhibitor of carbonic anhydrase, is teratogenic in mammalian embryos and when administered during early limb development causes unique limb defects in a time‐ and dose‐dependent manner. The regenerating urodele limb is often considered to be a good experimental analog of limb development and, if it employs the same mechanisms of tissue interactions during pattern formation, should be susceptible to teratogens which selectively disrupt developmental limb patterning. This study demonstrates that while carbonic anhydrase inhibition is toxic to the red‐backed salamander, Plethodon cinereus, it does not have the same teratogenic effect on limb regeneration as seen in mammalian limb development. Several points are considered as to why the regenerating limb, at least in this salamander species, may not be suitable for studying this class of teratogen.
Amniogenic band anomalies in a fifth‐month fetus and in a newborn from maternal oophorectomy during early pregnancy
Authors: Tanaka Osamu , Koh Toshikiyo , Otani Hiroki
Published: June 2005

A fifth‐month fetus and a newborn with amniogenic band anomalies were examined at autopsy. Both specimens were obtained from women who had undergone oophorectomy during early pregnancy. The dead male fetus was aborted spontaneously, and had a micrognathia, a right club foot, and a constriction ring on the left lower leg. The left fingers 2, 3, and 4 were attached to the placenta by a fibrous string. No internal anomaly was noted. In the other case, a male newborn was delivered at the 39th week of gestation and had an agenesis of the calvarium, a cleft lip with palate, an amputation of the right toe, and constriction rings on right fingers 3 and 4 and left finger 3. The placenta was attached to the left temporooccipital region of the head by a fibrous string. Also present was an atrial septum defect and a horseshoe kidney. Possible etiology is discussed in relation to the “amniogenic bands” hypotheses.
Effect of Shigella toxin on preimplantation mouse embryos in vitro
Authors: Olsen Wenche Marie , Storeng Ritsa
Published: June 2005

Preimplantation mouse embryos at the 4‐cell to 8‐cell stage were exposed to Shigella dysenteriae toxin at concentrations of 0.001‐100 pg/ml in vitro. The effect of the toxin was studied by morphological observation of the embryos to the blastocyst stage, by assessing protein synthesis with 14Cleucine incorporation, and by measuring embryonic adenosine triphosphate (ATP) content.

Preimplantation mouse embryos were highly sensitive to the toxin. All variables investigated were adversely influenced by the toxin. After a lag period of 24 hr, 0.01 pg/ml toxin inhibited development to the blastocyst stage and protein synthesis. Toxin concentrations of 1.0 pg/ml resulted in a significant decrease in ATP content.
Neonatal behavioral toxicity in rats following prenatal exposure to methanol
Authors: Infurna Robert , Weiss Bernard
Published: June 2005

Although methanol (MEOH) may assume a significant role as a fuel, which implies wide availability, little is known of its toxicity apart from acute poisoning episodes in human adults. Even less is known about its toxicity in developing organisms. This experiment studied the early behavioral development of rats whose mothers had consumed MEOH during gestation by measuring the responses of suckling (postnatal day 1) and nest‐seeking (postnatal day 10). Primigravida Long‐Evans rats were divided into three groups (N = 10). Two of the groups consumed drinking solutions of 2% MEOH instead of distilled water either on gestational days 15–17 (MEOH 1) or 17–19 (MEOH 2). No maternal toxicity was apparent as measured by weight gain, gestational duration, and daily fluid intake. Daily MEOH consumption averaged 2.5 gm/kg over the 3‐day period in both MEOH groups. Litter size, birth weight, and infant mortality did not differ among the three groups. Postnatal growth and date of eye opening were unaffected. MEOH pups required longer than controls to begin suckling on postnatal day 1. On postnatal day 10, they required more time to locate nesting material from their home cages. These data suggest that prenatal MEOH exposure induces behavioral abnormalities early in life that are unaccompanied by overt toxicity.
Leydig cell hyperplasia in fetal mice treated transplacentally with ethinyl estradiol
Authors: Yasuda Yoshiko , Konishi Hiroyoshi , Tanimura Takashi
Published: June 2005

Pregant female mice were given ethinyl estradiol on days 11 through 17 of gestation. On day 18 the dams were killed and the male fetuses were examined for testicular differentiation. Three of 12 males from dams treated with the highest dose of ethinyl estradiol showed cryptorchild testes with uterine tubes. Light and electron microscopic evaluation of the testes, both cryptorchid and normal, demonstrated foci of hyperplasia of Leydig cells showing cytoplasmic and nuclear pleomorphism, increase in lipid droplets, and decrease in smooth endoplasmic reticulum and ribosomes when compared to testes from control fetal mice. Morphometric determinations of the testes indicated that the number of Leydig cells in a unit area (mm2) in the interstitial tissue showed a dose‐response relationship to ethinyl estradiol in the normal testes. The number of Leydig cells in the testes exposed to the highest dose of estrogen showed a significant difference between cryptorchid and normal testes: the former had fewer Leydig cells than the latter. These morphological observations indicate that hyperplasia of Leydig cells of fetal mouse testis at term can be induced by transplacental treatment with ethinyl estradiol and suggest that a malignant transformation into a Leydig cell tumor is possible.
Vitamin A congeners
Authors: Rosa Franz W. , Wilk Ann L. , Kelsey Frances O.
Published: June 2005

Despite animal vitamin A congener teratogenicity in animal studies since 1954, striking human findings only arose in 1983 following isotretinoin (ITR) marketing for oral treatment of severe acne. By November 1985, 44 outcomes with central nervous system (CNS), cardioaortic (CV), microtia, facial palsy, micrognathia, cleft palate, and/or thymic aplasia defects, and 33 spontaneous abortions have been reported. The critical period for exposure appears to be two to five weeks postconception, although this is clinically inexact. ITR half life is less than a day, although a teratogenic metabolite, 4‐oxo‐isoretinoin, has a half life of several days. Seven defect outcomes and one stillbirth have been reported with another congener, etretinate (ETR), used for psoriasis. Three of these had meningomyeloceles. Half life of several months makes levels cumulative. Only one additional defect, which may have occurred by chance, is reported with use stopped before conception (4 months). Other discontinuations 1 to 6 months before conception had 11 normal outcomes and two spontaneous abortions. ITR and ETR dose ranged from 0.5 to 1.5 mg/kg. Normal outcomes are reported both with ITR and ETR, but some of these appear not to have been exposed during the critical period. Less striking defects, abortions, and normal outcomes are less well reported. Because vitamin A analogs are therapeutically important and unplanned outcome not always avoidable, further animal research is needed for better risk/benefits. Megadose vitamin A (retinol) use is widespread, but experience poorly observed. Eighteen suspicious birth defect outcomes have been reported from pregnancies with high dose exposure. Twelve had findings similar to those seen in animals and in human retinoid syndromes, e.g., CNS, CV, microtia, and clefts. Epidemiological controls are lacking to establish human teratogenicity, but based on animal studies and experience with ITR and ETR, avoding long term megadose Vitamin A use in fertile women is warranted.
Effects of methylmercury on the morphogenesis of the rat cerebellum
Authors: Howard John D. , Mottet N. Karle
Published: June 2005

Developing rat cerebellums were examined following continuous methylmercury exposure via maternal drinking water at 12.5 ppm during gestation and the suckling period. The continuous exposure resulted in reductions of the total cerebellar cell population and higher mercury tissue burdens than previous acute‐dose studies. Cell necrosis was not evident, but rather alterations in the pattern of mitotic figures were observed. A decreased number of cells in the methylmercury exposed cerebellums was associated with an increased number of mitotic figures in the early stages of mitosis and a decrease in the number in the middle and late stages. These in vivo exposure observations are consistent with in vitro cell cycle studies in which the cells were found to have accumulated in G2 and early M phases. Impaired cell proliferation is suggested to be a major mechanism of developmental neurotoxicity following continuous low‐does exposure to methylmercury.
Teratogenesis of calcium valproate in rabbits
Authors: Petrere Judith A. , Anderson John A. , Sakowski Raymond , Fitzgerald James E. , De La Iglesia Felix A.
Published: June 2005

The calcium salt of valproic acid (Valontin) has been proposed for use in the treatment of absence, myoclonic, and tonic clonic seizures of the primarily generalized type. The present study was conducted to determine the teratogenic potential of calcium valproate in rabbits. Groups of 20 Dutch‐belted rabbits were given oral doses of 50, 150, or 350 mg/kg on days 6–18 of gestation. A referece group was given 350 mg/kg sodium valproate and control groups were untreated or given vehicle alone. Animals were observed daily and body weights were recorded on gestation days 0, 6, 13, 18, and 30. Litter and fetal parameters were evaluated following uterotomies on day 30. No drug‐related clinical signs or deaths occurred. Postimplantation loss and the incidence of malformed vertebrae and ribs, rudimentary or absent pollices, and extra vertebrae and ribs were increased at 350 mg/kg with both calcium and sodium salts of valproic acid. At the 150‐mg/kg dose level, calcium valproate markedly increased the incidence of supernumerary ribs. No teratogenic or embryotoxic effects were seen with calcium valproate at 50 mg/kg. These data indicate that the sodium and calcium salts of valproic acid exhibit teratogenic potential in rabbits.
Abnormalities of the ear associated with exencephaly in mouse fetuses induced by maternal exposure to cadmium
Authors: Padmanabhan R.
Published: June 2005

Exencephaly was induced in mouse fetuses by maternal injection of cadmium chloride (CdCl2) on day 7 of gestation. The heads of exencephalic, nonexencephalic experimental, and control fetuses were embedded in paraffin and sections were stained with hematoxylin and eosin. Compared to those of controls, the ears of the exencephalic fetuses were smaller (microtia) and low set. The meatal plug representing the external auditory canal was thick, variously branched, and often directed inferiorly. Usually, there were just two ossicles. The stapedial artery, facial nerve, and stapedius muscle were hypoplastic; the tensor tympani was small or absent. There were 1.0 to 2.0 turns of the cochlea in contrast to 2.5 turns in the controls. The organ of Corti was underdifferentiated; the spiral ganglion had fewer cells. In the control, the long axes of the anterior and posterior semicircular ducts were at right angles to each other and in vertical planes, but in the exencephalics, they tended more laterally towards the horizontal plane. The differentiation of the cristae ampullares and maculae was also severely affected. In several specimens, the entire membranous labyrinth had been distended; these labyrinths also had unusual epithelial infoldings. In cadmium‐treated nonexencephalic fetuses, the external ears were normal and appropriate to the body size; five of them were examined histologically; in all, the five middle ear contents were hypoplastic; in three, the cochlea had a maximum of two turns and the organ of Corti, crista ampullaris, and macula were hypoplastic. By an analogy to abnormalities of mutants with neural tube defects, it is suggested that the exencephaly induced by cadmium might affect the differentiation of the ear. Partial involvement of the ear in nonexencephalic experimental embryos may be the result of direct action of cadmium during critical stages of development.
Teratogenic effect of D‐amphetamine sulphate: Histodifferentiation and electrocardiogram pattern of mouse embryonic heart
Authors: Fein Amos , Shviro Yardena , Manoach Mordechai , Nebel Laslo
Published: June 2005

Pregnant albino mice (ICR random‐bred strain) received daily injections of 50 or 100 mg/kg body weight of D‐amphetamine sulphate between days 9 and 11 of gestation. Parallel control animals were injected with saline solution. Treated mice were sacrificed on day 15 or 19 of gestation. The embryos were examined for gross malformations and direct embryonic ECG recordings were made; they were weighed, and their hearts were carefully dissected. Microscopic sections of the heart were stained with hematoxylin and eosin. It was found that high doses of D‐amphetamine raised the incidence of mortality in the treated pregnant mice up to 40%. The resorption rate in the survivors was high (up to 58%) following the high dose of the drug. Up to 15% of the embryos from the treated groups showed gross malformations, including skeletal and eye malformations and exencephaly. The electrocardiogram (ECG) recordings in most 19‐day‐old embryos from both treated groups showed a pattern with prolonged Q‐T interval (PQT), similar to that of control embryos in the intermediate developmental stages (days 14–16 of gestation). The ECG of control embryos (from day 17 on) resembled that of prenatal fetuses. Microscopically, the hearts of treated embryos showed a large number of undifferentiated cardiac myoblasts. It can be inferred that high doses of D‐amphetamine affect embryonic development generally and delay the histodifferentiation of the myocardium, resulting in incomplete maturation of the cardiac muscles, thus leading to the immature ECG pattern, with PQT intervals.
Effects of protein deficiency on the teratogenicity of cytochalasins in mice
Authors: Singh Jarnail , Hood Ronald D.
Published: June 2005

The developmental toxicity of cytochalasins B (CB) and D (CD) was evaluated in protein‐deprived mice. Pregnant CD‐1 mice were assigned to control (26%), 16%, 8%, or 4% dietary protein groups on gestation day 1 and dosed by gavage with 0 or 1.5 mg/kg CB or CD on gestation day 8 (plug = day 1). They were killed and subjected to teratological examination on day 18. CD, but not CB, increased prenatal mortality but failed to interact significantly with dietary protein level. Fetal weights were decreased in the 4% and 8% dietary protein groups, but cytochalasin treatment did not exacerbate this effect. Cytochalasin treatment was associated with gross fetal malformations, primarily neural tube defects. Although CB and CD did not significantly increase the percentage of grossly malformed fetuses per litter, the data was suggestive of such an effect, and the incidence of affected litters was increased by cytochalasin treatment in all but the 4% protein group. Skeletal defects, such as jaw malformations, rib or sternebrae variations, and unossified skull bones appeared to be increased by both cytochalasin treatment and dietary protein deficiency. The differences from control values were nonsignificant, however, except for some cases of cytochalasin effects on skull ossification. These results show a general lack of effect of protein deprivation on the developmental toxicity of cytochalasins.
Deleterious effects of adrenocorticotrophic hormone administration during late pregnancy upon offspring somatic, neurological, and sexual development in mice
Authors: Harvey P. W. , Chevins P. F. D.
Published: June 2005

The influence of administration of adrenocorticotrophic hormone (ACTH) during days 12–17 of pregnancy upon somatic, neurological, and neuromuscular development of offspring in mice was studied. The effects upon the onset of puberty in female offspring was also examined. Litters from mice given the higher of two doses of ACTH (1 IU/day or 8 IU/day) showed lower body weights at birth and weaning than controls. This treatment also increased pre‐ and postnatal mortality rates, although not significantly. Litters from mice treated with either dose of ACTH showed retarded development of the forelimb and hindlimb grasp reflexes, the body righting reflex, the auditory startle response, and eye opening. Although ear opening was delayed in litters from ACTH‐treated mice, results did not achieve statistical significance. Study of female offspring housed in small groups revealed that one indicator of puberty, vaginal opening, was delayed in female offspring of ACTH‐treated mice. Experiments were conducted to identify factors mediating this syndrome: ACTH did not depress maternal food intake or alter the length of pregnancy, therefore fetal undernutrition or premature birth can be excluded as mediating factors. All litters were fostered to untreated mice to control for postnatal factors influencing development. As ACTH cannot cross the placenta, the syndrome is likely to result from in utero exposure to abnormally high concentrations of glucocorticosteroids of maternal origin. It is concluded that such alterations to the fetal environment can exert a deleterious influence upon somatic, neurological, and sexual development, and that hormones of the maternal pituitary‐adrenocortical axis may naturally act to regulate general development of the fetus.
In vitro teratogenicity of ethylenethiourea in the rat
Authors: Daston George P. , Ebron Marian T. , Carver Brenda , Stefanadis James G.
Published: June 2005

We have demonstrated that ethylenethiourea (ETU) is a potent teratogen to the rat embryo developing in vitro. Sprague Dawley rat embryos were explanted on gestation day 10 and cultured for 48 hours in the presence of 40–200 μg/ml ETU. This resulted in a dose‐related inhibition of growth and differentiation as assessed by crown‐rump length, protein and DNA content, and somite number and in an increase in the frequency of abnormalities. A variety of anomalies was produced, including fluid accumulation in the brain (hydrocephalus), decreased mandibular size, decreased telencephalon size, abnormal dorsiflexion, as well as subectodermal blisters on the tail and limb buds and maxilla. Frank malformations have been observed at these same sites–hydrocephalus, brachygnathia, kyphosis, limb and tail defects, cleft palate–in the term fetus in vivo. The presence of abnormal fluid accumulation in the embryos–distended neural tube and subectodermal blisters–suggested that the osmotic environment of the embryo had been altered by ETU exposure. Osmolality of the exocoelomic fluid (ECF) surrounding the embryo was measured after 48 hours of exposure to a concentration of ETU that caused nearly a 100% incidence of subectodermal blisters. ECF osmolality was found to be significantly lower than that of control embryos. Lowered osmolality would cause water to move out of the ECF, presumably causing the observed fluid accumulation in the embryo. It is speculated that altered osmotic balance and localized edema in the embryo are contributory steps in the formation of defects after ETU exposure.
Cardiac and noncardiac malformations: Observations in a population‐based study
Authors: Ferencz Charlotte , Rubin Judith D. , McCarter Robert J. , Boughman Joann A. , Wilson P. David , Brenner Joel I. , Neill Catherine A. , Perry Lowell W. , Hepner Seymour I. , Downing John W.
Published: June 2005

A regional case‐control study of congenital cardiovascular malformations (CCVMs) searches for all live‐born infants in the community in whom the cardiac diagnosis has been confirmed by echocardiography, cardiac catheterization, surgery, or autopsy. Their families are studied in comparison to those of a representative sample of resident live‐born infants. Detailed descriptions of noncardiac abnormalities are obtained from physician reports and maternal interviews expanded by medical record and death certificate data.

Among 1,494 cases and 1,572 controls, chromosomal abnormalities, syndromes, heritable disorders, and suspect syndromes occurred with an overwhelming excess in cases (chromosomes, P < 10−4; syndromes/heritable disorders, P < .005). Abnormalities affecting chromosomes 13, 18, and 21 constituted 93% of the cytogenetic defects. Syndromes and heritable disorders were of 39 types. Nonsyndromic abnormalities were three times more frequent in cases than in controls (P < .005). Case excesses occurred for central nervous system malformations, eye disorders, major abdominal wall defects, and abnormalities of the alimentary and urinary tracts. Severe anomalies frequent among cases were those which also occur in certain recognized syndromes, and it is suggested that paired combinations of cardiac and other midline anomalies may represent “formes frustes” of syndromes with similar though variable phenotypic expressions. Cleft lip and palate, inguinal hernia, and lower limb anomalies occurred with equal frequency, suggesting their association with CCVMs by chance alone.
A new method to express embryotoxic data obtained in vitro on whole murine embryos
Authors: Picard J. J. , Van Maele‐Fabry G.
Published: June 2005

This report proposes to express the effect of drugs in the whole embryo culture system by a new method using an intrinsic reference. Percentages of malformed embryos or other defects in development, expressed as percentages of controls, are plotted against concentrations of the drug expressed as percentages of the concentration inducing 50% embryolethality (ELC50). It is suggested that the slope generated by this method is directly related to the intensity of the in vitro teratogenic potential of the agent and allows an estimation of the specific interference with developmental processes. The method has been applied to data obtained from the literature and pertaining to 22 drugs. The slope generated by these drugs varied widely. The effect of these drugs could be meaningfully compared in spite of the wide range of ELC50 displayed by the drugs. In addition, results obtained for two drugs in different laboratories using different methods and species were in fair agreement when they were compared by using the proposed method. Finally, it is suggested that the method provides an improved means to inquire if there is any relevance of in vitro data to teratological results obtained in vivo.
Fate of adriamycin‐induced dilated renal pelvis in the fetal rat: Functional and morphological effects in the offspring
Authors: Kavlock Robert J. , Rehnberg Blair F. , Rogers Ellen H.
Published: June 2005

Previously we reported that gestational exposure to Adriamycin, an anthracycline antibiotic used in the treatment of neoplasms, reduced renal function in the neonatal rat, and we suggested that alterations in the development of the renal papilla might be responsible for the dysfunction. In this study we exposed groups of Sprague‐Dawley rats to 0, 1.0, 1.25, or 1.5 mg/kg of Adriamycin on gestation days 10–12, a period previously shown to be effective in altering postnatal renal function with this compound. Offspring were evaluated at several developmental periods in order to (1) precisely define the morphological status of the urogenital system in Adriamycin‐treated offspring; (2) replicate the finding of a decreased renal concentrating ability in the neonates; (3) determine the transience/permanence of any morphological effect; and (4) correlate any permanent alterations in urogenital morphology with our indicator of neonatal functional competence. Maternal Adriamycin treatment induced alterations in the development of the renal papilla that persisted well into the postnatal life of the offspring. The first appearance of the morphological alteration occurred in the absence of other general indicators of developmental toxicity such as growth retardation. The determination of the ultimate fate and functional consequences of the structural alterations required postnatal evaluations of the renal system. Finally, a relatively simple test of renal function in the neonate proved to be predictive of the permanence of the morphological effect, and the absolute test result showed a strong correlation with the incidence of the morphological effect in the overall population.
Neuronal degeneration caused by ethylenethiourea in neuronal monocell layers in vitro and in fetal rat brain in vivo
Authors: Khera K. S.
Published: June 2005

The monocell layers, containing a mixture of neuronal and non‐neuronal (primarily glial) cells, were obtained by growing cells dissociated from trypsinized fetal brains of 19‐day pregnant rats under optimum conditions. Ethylenethiourea (ETU), at ≥ .5 mM concentrations, caused in monocell layers in vitro a necrosis of neuronal cells and a marked depression in the formation of neurites and fascicles without any noticeable change in the non‐neuronal cells. In the in vivo study, ETU orally administered as a single 30 or 45 mg/kg dose to rats on day 19 of pregnancy was found to induce necrosis of neuroblasts in the fetal CNS after 18 and 24 hours of dosing and a high incidence of hydrocephalus in postnatal pups at both doses. In an in vivo/in vitro experiment, rat fetal brains from 19‐day pregnant dams which had previously been dosed with 80 or 120 mg ETU/kg were trypsinized and then dissociated into a cell suspension in a nutrient medium. The total number of viable cells in the suspension was significantly reduced compared to the number in the control suspension. The test suspension with cell density adjusted to that in the control suspension grew into monocell layers manifesting a marked decreased population of neuronal cells with a concomitantly increased population of non‐neuronal cells. It was concluded that the target of ETU action was most likely the neuronal cells rather than the organization of nervous tissue per se.