bluuebunny/crossref_metadata_2025 huggingface dataset:
Blood flow during pregnancy in the rat: III. Alterations following mirex treatment
Authors: Buelke‐Sam J. , Byrd R. A. , Nelson C. J.
Published: June 2005

The radiolabeled microsphere technique was used to evaluate intrauterine and maternal organ blood flow in CD rats on day 6, 10, or 16 of gestation. Pregnant animals received an oral dose of 10 mg/kg mirex on day 5 (for day 6 determinations), days 5–9 (for day 10 determinations), days 5–14 (for day 16 determinations), or no treatment (controls). On day 6, absolute blood flow (ml/min) to the stomach was reduced significantly in mirex‐treated rats, but no other statistically significant changes were observed. On day 10 in mirex‐treated rats, maternal cardiac output was decreased significantly, weights of uterus, ovaries, heart, and spleen were decreased while liver weights were increased. Absolute blood flow to the lungs, urinary bladder, kidneys, ovaries, and uterus and total conceptus was decreased significantly on day 10. On day 16, ovarian and uterine weight and blood flow in mirex‐exposed rats were no longer significantly different from control animals. However, blood flow to the stomach, spleen, liver, kidney, and adrenal was reduced while liver weight had increased markedly. The mean number of viable fetuses/litter was reduced to 5.4 ± 2.2 in the treated group compared to 11.6 ± 0.4 in day 16 controls. Fetal weight was decreased significantly and resorption weights and absolute blood flow were significantly increased in the mirex group. Edema was observed in all live fetuses from mirex‐treated dams evaluated on day 16 of gestation. Thus, overall effects of mirex treatment on maternal cardiac output, and blood flow to the stomach, spleen, liver, kidneys, adrenals, and uterus suggest maternal toxicity may play a large role in adverse fetal outcome. The marked decrease in blood flow to the uterus and total conceptus seen on day 10 suggests that hypoxia during organogenesis may contribute to reduced fetal weight, edema, and death observed on day 16 of gestation in treated litters.
Oxygen consumption and survival prediction in neonatal rats exposed to prenatal hypervitaminosis A
Authors: Newman L. M. , Johnson E. M. , Cadogan A. S. A.
Published: June 2005

Fetal exposure to excess vitamin A results in a highly variable degree of lung pathology and high neonatal mortality in the Long–Evans rat. The present study evaluated O2 consumption in newborn of vitamin A‐treated, vehicle‐treated, and untreated pregnancies on five consecutive postnatal days beginning with the day of delivery (D0). Pregnant female rats were treated by gavage with 160,000 USP units of retinyl acetate dissolved in 0.5 ml corn oil on days 15 through 19 of gestation. Vehicle and undisturbed controls were run concurrently. All animals delivered spontaneously, and the pups were tattooed and individually tested in a closed system consisting of three chambers submerged within a thermostatically controlled water bath at 33°C.

Vitamin A‐exposed pups, as a group, have significantly lower QO2 (ml O2 consumed/min/kg body weight) values than controls through postnatal day 2 (p < 0.05). By days 3 and 4 of age, the mean QO2 values of surviving vitamin A‐treated pups were similar to those of controls. A QO2 of 30 or greater on day 0 appears to be critical for early neonatal survival of vitamin A‐exposed pups, as 87% of the pups with initial QO2 < 30 died prior to day 4. Oxygen consumption rates in teratogen‐exposed pups exhibiting low QO2 on day 0 rarely reached normal levels. In contrast, the occasional control pup with such low initial levels were well within normal limits (X̄ ± 1 SD) by the following day.

These studies demonstrate a marked effect of prenatal insult on respiratory function and strongly suggest that the nonivasive determination of QO2, 2–6 hours after birth provides a means to identify both moderately and severely affected individuals thereby permitting sequential study of their ensuing development of atelectasis neonatorum and apparent hyalin membrane disease.
Ornithine decarboxylase inhibitors and fetal growth retardation in mice
Authors: Manen Carol‐Ann , Hood Ronald D. , Farina Joseph
Published: June 2005

Putrescine (PUT) and the putrescine analogues, 1,3‐diaminopropane (DAP) and 1,6‐diaminohexane (DAH), were administered to pregnant female mice during the time of maximal fetal ornithine decarboxylase (ODC) activity, days 10–14 of gestation. Such treatment resulted in an inhibition of fetal ODC activity, as measured 2 hours later, and a proportional decrease in fetal weight, as measured on day 18 of gestation. The order of effectiveness for these compounds was DAP > DAH > PUT. Neither DAP nor DAH nor PUT were fetocidal nor maternally lethal under the treatment regimen employed. The generality of the effect of these compounds, i.e., the retardation of fetal growth and the lack of gross malformations, is consistent with the hypothesis that they are interfering with a primary process, probably protein synthesis. The restricted time span of effectiveness implies that these compounds are specific inhibitors of ODC and that decreased ODC activity is producing an effect on growth.
Assessment of adult skeletons to detect prenatal exposure to trypan blue in mice
Authors: Beck Sidney L.
Published: June 2005

A Skeletal Variant Assay System (SVAS) consisting of a group of 88 spontaneously occurring qualitative variations of the adult mouse skeleton was studied in CD‐1 mice which had been exposed in utero by way of three daily ip injections of their dams on days 7–9 of gestation with trypan blue. Treatment groups received daily doses of 0.25 cc of 0, .037, .075, .15, or .30% trypan blue dissolved in 0.9% NaCl. Two separate series of experiments were performed, and skeletons were examined at 62 ± 2 days postnatal.

Sixty‐six and 58 of the variants occurred in the two series, respectively. Frequencies of occurrence of substantial numbers of variants differed from Untreated (UNTD) and Vehicle‐Treated (VEH) values in a dose‐related manner for both series. At the high dose 18 and 22 variants occurred with significantly different (P < .01) frequencies from UNTD in the two series. Contrasting high‐dose animals with vehicle controls revealed significant differences in 24 and 17 variants. There were 13 and 14 variants in the two series, respectively, which differed from both UNTD and VEH. If one considers differences at P < .01 in one comparison and P < .05 in the other, then 22 and 18 variants qualify as being signficantly different from both controls in the two series.

Agreement between the two series was excellent regarding which variants were affected. Several differed significantly from both UNTD and VEH in both series of experiments. Among these were a number which appeared more or less specific to trypan blue exposure. They include Dyssymphysis of the Atlas, Carpal Fusions, and Tarsal Fusions. Although increased frequency of an Interfrontal bone is seen with several treatments, the magnitude of the response and the low doses at which it is elicited are unique to trypan blue exposure. Numerous low‐dose effects are striking in this set of experiments, making the SVAS a very sensitive indicator of trypan blue exposure.

In addition to the variants mentioned, a large cluster of cervical (C) vertebrae variants, including dyssymphyses, fusions, imperfect transverse foramina of C1 and C2, and accessory transverse foramina of C3–C6, as well as vertebral fusions at various levels (especially cervical, sacral, and caudal), appear to be the principal effects of exposure to this compound. In addition, rib malformations at the high dose level, and increased frequency of occurrence of 27‐presacral vertebrae at all dose levels, were important effects.

By all criteria applied, the SVAS is able to detect prenatal exposure to trypan blue in adult skeletons even in the absence of any gross morphological abnormalities, and can detect exposure at well below the teratogenic dose level.
Behavioral and reproductive effects of chronic developmental exposure to brominated vegetable oil in rats
Authors: Vorhees Charles V. , Butcher Richard E. , Wootten Virginia , Brunner Robert L.
Published: June 2005

Adult Sprague‐Dawley rats were fed diets containing 0, 0.25, 0.5, 1.0, or 2.0% of the food additive brominated vegetable (soybean) oil (BVO) for 2 weeks prior to mating. After conception, the diets were continued throughout gestation and lactation for the females. The same diets were also provided to the dams' offspring throughout their development (up to 90–120 days of age). BVO at 2.0% of the diet completely blocked reproduction. BVO at 1.0% of the diet severely impaired conception, reduced maternal body weight, and produced slightly reduced litter sizes but no evidence of malformations. At this dose postnatal mortality was high, and survivors showed impaired growth and severe behavioral impairments on a battery of standardized tests of functional development. After weaning, adequate data could not be obtained because of the high mortality rate in this group. BVO at 0.5% of the diet produced less reproductive interference and much less offspring mortality or impairment of growth, but produced behavioral impairments almost as severe as seen in the BVO 1.0% group. In addition, this group exhibited severely reduced postweaning activity, delayed vaginal patency development, and reduced day‐90 weight. BVO at 0.25% of the diet produced reproductive deficits similar to the BVO 0.5% group, but less severe effects on growth and behavioral development. This group showed no significant increase in offspring mortality. The data demonstrate clear evidence of dose‐related physical and behavioral developmental toxicity.
Interaction of dietary zinc, genetic strain, and acetazolamide in teratogenesis in mice
Authors: Hackman Robert M. , Hurley Lucille S.
Published: June 2005

The effect of dietary zinc and genetic strain on acetazolamide‐induced malformations was assessed. CBA (sensitive) and SWV (resistant) mice were fed purified diets containing five different levels of zinc throughout gestation and were given acetazolamide orally for a limited period during organogenesis. Controls received either no treatment or the drug vehicle. Litters were assessed for resorptions and malformations at term. The significance for influencing litter outcome was tested for the three main treatments: strain, dietary zinc level, and acetazolamide dose, plus their interactions. The magnitude of the litter response was strongly influenced by strain. The incidence of forelimb ectrodactyly, a characteristic malformation caused by acetazolamide, was much greater in CBA than in SWV fetuses. SWV fetuses had no ectrodactyly when dams were fed at least 9 μg/g zinc, but 5–8% showed ectrodactyly when dams received a zinc‐deficient (0.4 or 4.5 μg/g) diet. The incidence of ectrodactyly in the CBA strain decreased as dietary zinc increased, but was still present when dams were fed a high (1,000 μg/g) zinc diet. The incidence of resorptions and total abnormal sites from litters of dams receiving acetazolamide decreased as dietary zinc increased, with the magnitude of the response being influenced by the strain. A significant (dietary zinc × acetazolamide) and (strain × acetazolamide) interaction was found for the ectrodactyly response. The results demonstrate the importance of considering interactions among genetic strain, diet, and drugs, as well as single factors as determinants of fetal risk.
In vitro studies on methyl mercury distribution in human blood
Authors: Greener Yigal , Kochen Joseph A.
Published: June 2005

Studies comparing the methyl mercury (mHg) content of maternal and newborn blood have shown increased levels in the newborn. This has been attributed to facilitated transplacental diffusion because of high fetal hematocrit (Hct). This study shows the converse, that the diffusion of mHg diminishes progressively with increasing Hct. The diffusion of m203Hg across a Millipore membrane (0.45 μm) separating compartments A and B of a diffusion cell was studied. When both compartments contained saline or plasma alone, equilibration from A to B occurred in 5 h. Introduction of human red blood cells (RBC) in saline (Hct 20%) into B resulted in a twofold increase in diffusion of mHg when compared to saline alone. Increasing Hct in saline in compartment B resulted in a progressive decrease in diffusion (r = −0.95, P < 0.001). The presence of RBC in plasma (Hct 20%) in B resulted in a 70% decrease in diffusion; with increasing Hct, diffusion was further reduced (r = −0.95, P < 0.001). Direct addition of mHg to RBC in saline resulted in 98% RBC uptake. Increasing concentrations of plasma (at a constant Hct) resulted in a progressive decrease in RBC uptake. In undiluted plasma at Hct 14%, RBC uptake of mHg was 35%. Plasma electrophoresis showed that much of the mHg was associated with a high‐molecular‐weight lipoprotein fraction. Plasma components appear to be important in the distribution of mHg in blood, and may be a factor in the relatively higher blood levels in the fetus.
Early morphological abnormalities in splotch mouse embryos and predisposition to gene‐ and retinoic acid‐induced neural tube defects
Authors: Dempsey Ellen E. , Trasler Daphne G.
Published: June 2005

Genetic and environmental factors contribute to an individual's neural tube defect liability. In the mouse, the gene mutation Splotch (Sp) causes a pigmentation defect in heterozygotes while homozygotes have spina bifida ± exencephaly. Splotch homozygotes, heterozygotes, and wild‐type embryos were examined for somite number, anterior neuropore closure, and posterior neuropore length. The aim was to distinguish potentially affected homozygotes early in pathogenesis and find a morphological basis for increased teratogen susceptibility in heterozygotes. Posterior neuropore closure as well as anterior neuropore closure was significantly delayed in potentially affected Sp as compared to wild‐type litter embryos exceeding the incidence found in day‐10‐diagnosed homozygotes. Part of this excess was attributed to a transient delay in heterozygotes which in turn might predispose to retinoic acid‐induced neural tube defects. This idea was supported by an outcross of Sp heterozygote males by inbred SWV females and wild‐type males by SWV where a significant increase in retinoic acid‐induced neural tube defects was found in Sp carrier litters.
Morphologic study of effects of kanamycin on the developing cochlea of the rat
Authors: Onejeme Afamefune U. , Khan Khalid M.
Published: June 2005

The development of the rat inner ear starts about day 9 of a 22‐day gestational period. The sensory and supporting cells are morphologically identifiable by day 18 of gestation; however, auditory function is not evident until day 9 postnatally. The organ of Corti attains adult maturity about day 16 postnatally. Morphologic and physiologic studies have shown that administration of sublethal doses of aminoglycosidic antibiotics, including kanamycin, damages the sensory and supporting cells of the inner ear in mammals. This results in the impairment of auditory function. This study was designed to determine the earliest stage in cochlear duct development at which kanamycin toxicity can be morphologically detected. A sublethal dose of kanamycin was administered to pregnant rats on days 10 through 20 of gestation and to neonates from days 1 to 8 or from days 8 to 16 postnatally. The inner ears were dissected and processed for light microscopic and ultrastructural observations. The cochlear ducts of fetuses exposed in utero to kanamycin and those of neonates exposed from days to 1 to 8 postnatally were unaffected. Kanamycin toxicity was evident in the cochlear ducts of neonates exposed from days 8 to 16 postnatally. The most severe damage occurred in the basal coil of the cochlea where in many instances sensory cells were totally absent. The sensory cells in the middle and apical coils exhibited abnormal morphology. These results suggest: (1) kanamycin does not have any permanent toxic effects on the rat cochlear duct during gestation and the first week of postnatal life. This provides a basis for further studies into the possible pharmacologic application of this finding in humans. (2) A correlation exists between the initiation of auditory function and the vulnerability of the organ of Corti to kanamycin toxicity.
Infants with congenital limb reduction registered in the Swedish Register of congenital malformations
Authors: Källén Bengt , Rahmani Tahereh M.‐Z. , Winberg Jan
Published: June 2005

Limb reduction defects reported to the Swedish Register of Congenital Malformations 1965–1979 have been analyzed from a monitoring point of view. The infants were first studied with respect to the site of reduction malformation and the simultaneous presence of more than one such reduction site. Reductions often occurring together were thought to have a common pathogenesis (etiology) and were therefore treated as one unity although some such groups (e.g., radial longitudinal reductions) are probably heterogeneous. The material was therefore divided into 11 subgroups; the eleventh is represented by infants with more than one unrelated reduction. Maternal age distribution was approximately normal. There is a male preponderance of all reduction types. In the whole group, 20% of the infants died perinatally, but this percentage was higher for some groups (e.g., amelidphocomelia) than for others (e.g., amputations and unspecific handfoot reductions). In more than 30% of the infants, nonlimb malformations were also present. Such infants showed the highest death rate of all. The infants had a lower than expected birth weight (gestational length was not known). The time trends for the various subgroups differed. Amelidphocomelia declined in frequency but the unspecific handfoot reductions showed a marked increase during the last few years, possibly owing to better ascertainment. The significance of monitoring reduction malformations as smaller subgroups is stressed, as marked changes may occur within a subgroup without a noticeable change in the total number of reductions.
Intrauterine growth of the Guinea pig fetal–placental unit throughout pregnancy: Regulation by utero‐placental blood flow
Authors: Garris David R.
Published: June 2005

The relationships between uterine blood flow (UBF) and growth related changes in guinea pig placental weight, fetal weight, and crown‐rump (C–R) length were examined at 5‐day intervals throughout pregnancy. Between days 5 and 20 (Day 0 = ovulation) of pregnancy, UBF reached peak levels that were related to increases in total uterine weight as a result of fetal‐placental differentiation. Between days 20 and 40 of pregnancy, UBF remained at constant, basal levels while placental weight increased at a rate of approximately 500 mg per 5‐day interval. During this time period, fetal weight and C–R length continued to increase, but at a less rapid rate. Between days 40 and 55 of pregnancy, a secondary elevation in UBF was observed that was temporally related to third trimester growth of the fetus (ie, weight and C–R length). Near term (day 65), UBF decreased and placental growth reached a plateau, whereas fetal weight and C–R length continued to increase. In order to determine the direct effects of UBF on regulating fetal‐placental growth, mid‐gestational (days 35–50) pregnant guinea pigs were subjected to UBF reduction and the growth parameters of the manipulated fetal‐placental units were then examined at 2, 3, 4, and 10 days post‐alteration and compared to controls. The reduction in UBF at hyperemic pregnancy sites to basal flow levels resulted in an abrupt curtailment of subsequent placental growth noticeable within 48 hr of the vascular reduction. Subsequently, fetal weight and crown‐rump length parameters were depressed with respect to controls, but not until 4 and 10 days post‐alteration, respectively.

The results of the present study indicate that the temporal changes in UBF during gestation are associated with intrauterine growth and development of the guinea pig fetal‐placental unit. Early gestational elevations in UBF are closely associated with initial placental formation, and experimental reduction in UBF has the greatest effects on placental growth. Fetal growth parameters are regulated by placental supply until late gestation when they have a transitory, but an apparently stimulatory, effect on utero‐placental circulation.
Morphologic development of the fetal trisomy 19 mouse
Authors: Bersu Edward T.
Published: June 2005

Trisomy 19 mice show a characteristic pattern of delayed morphologic development when compared with normal littermates during the second half of gestation. Examinations of the external phenotype and sectioned fetuses, and skeletal maturation at later days, suggest that trisomy 19 has little recognizable effect on morphogenesis prior to 10 days. Trisomic conceptuses collected at subsequent 24‐hour intervals show a 1‐day lag in weight gain and begin to show a progressive and uniform delay in differentiation so that 14‐ and 15‐day animals resemble 13‐ and 14‐day normal fetuses, respectively. There is no further recognizable increase in this delay through term. There was no striking change in numbers of viable trisomic conceptuses collected throughout the period from 10 days to birth. These observations suggest that most trisomies surviving at 10 days will develop to term, with the major effect of the aneuploid genome being to delay the otherwise normal‐appearing growth and development of the affected conceptuses. In all cases, the litters were from crosses between mice doubly heterozygous for the (5.19) and (9.19) Robertsonian translocation chromosomes.
Does agent orange cause birth defects?
Authors: Friedman J. M.
Published: June 2005

Large quantities of the defoliant, Agent Orange, were sprayed in Vietnam during the war. Agent Orange was composed of two herbicides: 2,4‐D and 2,4,5‐T, the latter contaminated by small amounts of a highly toxic dioxin (TCDD). The constituents of Agent Orange are capable of producing gene mutations and chromosomal aberrations, at least in some experimental circumstances. TCDD and 2,4,5‐T are teratogenic in mice and perhaps in other mammals, but the teratogenicity of these chemicals has not been convincingly demonstrated in humans. There is currently no scientific evidence which indicates that men who were previously exposed to Agent Orange are at increased risk of having children with birth defects, but available data are inadequate to assess this possibility critically.
Optic vesicle defects induced by vincristine sulfate: An in vivo and in vitro study in the mouse embryo
Authors: Svoboda K. K. , O'Shea K. S.
Published: June 2005

The optic vesicle develops from cuboidal neuroepithelial cells which become high‐columnar, then become wedge‐shaped. Vincristine sulfate, a microtubule inhibitor, was used to study the role of microtubules in optic vesicle formation. Swiss‐Webster mice were injected with vincristine sulfate on the eighth day of gestation, placebo females received an equivalent volume of saline, and additional females were not injected. All embryos were harvested on the 10th day of gestation. Additional embryos were cultured by the whole embryo culture technique described by New et al. ('73) beginning on the ninth day of gestation for 24 hours. When embryos were harvested on the 10th day of gestation, crown–rump lengths, developmental stage, and the number of visible anomalies were recorded. Embryos were then examined using light, transmission, and scanning electron microscopy. Embryos exposed to vincristine sulfate in vivo or in vitro were significantly smaller and developmentally delayed when compared to the control groups. The embryos treated in vivo appeared to be more severely affected than those exposed in vitro. Observed malformations were similar in both experimental groups, and consisted mainly of closure defects of the cephalic neural folds and defective formation of the optic vesicles. The optic vesicle defects ranged from complete absence to asymmetrical development. Microtubules appeared to be disorganized, S‐shaped, or incorporated into paracrystalline inclusion structures.
Evidence for repair in trypan blue‐treated mouse egg cylinders: An electron microscopic study
Authors: Hamburgh Max , Glezer Ilya , Sabater Juan , Louis‐Jacques Gerard , Francois Max , Mendoza Lorenzo A.
Published: June 2005

The question of whether mammalian fetuses can correct damage induced by teratogens during early stages of embryogenesis was reinvestigated. Toward this purpose female mice were injected on day 6 of gestation with the teratogenic dye trypan blue. Within 6, 24, and 48 hr of exposure to the teratogen, egg cylinders were removed, sectioned, and prepared for electron microscopic analysis. The following organelles were examined: (1) mitochondria, (2) Golgi apparatus, (3) endoplasmic reticulum, and (4) free polysomes. On the ultrastructural level, exposure to trypan blue lead within 6 hr to fragmentation of the endoplasmic reticulum and a depletion of free polysomes in the endoderm of the egg cylinders. In ectodermal cells only the distribution of polysomes was disturbed following exposure to trypan blue. Egg cylinders harvested 24 hr after injection of trypan blue had partially recovered. Their endoplasmic reticulum and polysomes appeared closer to controls. The cells of both germ layers of most egg cylinders obtained 48 hr after injection were indistinguishable from controls when viewed with the electron microscope. No consistent changes were found in mitochondria or Golgi apparatus following trypan blue treatment. It is concluded that mouse embryos appear to be able to correct damage sustained during the egg cylinder stage, and that in spite of earlier injury affecting both germ layers such egg cylinders can develop normally as revealed by microscopic examination.
Effects of interferon and encephalomyocarditis virus on in vitro development of preimplantation mouse embryos with and without the zona pellucida
Authors: Zusman Igor , Engelhard Dan , Yaffe Perhija , Ron Arie , Panet Amos , Ornoy Asher
Published: June 2005

Development of preimplantation mouse embryos, with or without the zona pellucida, in the presence of interferon (IFN) and mouse encephalomyocarditis (EMC) virus was studied using the in vitro culture method. The embryos (2‐ to 8‐cell stages) were obtained from superovulated mice and cultured in modified Witten's medium under paraffin oil in 5% CO2 in air at 37°C. Removal of the zona pellucida does not affect the subsequent development of the embryos: 90% of embryos with and 87% of embryos without the zona pellucida reached the morula–early blastocyst stages. Mouse IFN (104 units/ml) had no inhibitory effect on the developmental ability of the preimplantation embryos with or without the zona pellucida: 88 and 89% of the embryos in each group, respectively, reached the morula–early blastocyst stages. The preimplantation mouse embryos were sensitive to the embryotoxic effect of EMC virus: at a multiplicity of 20 infection particles per embryo the development of 43% of embryos was inhibited. The zona pellucida had no significant protective effect: Its removal changed only slightly the susceptibility of the preimplantation embryos to this virus. Pretreatment of embryos with IFN did not protect them from the embryotoxic effect of EMC virus. This work indicates that preimplantation mouse embryos appear to be resistant for both the antiviral and antiproliferative activities of IFN.
Incidence and potentiation of external and internal fetal anomalies resulting from chlordiazepoxide and amitriptyline alone and in combination
Authors: Beyer Bruce K. , Guram Malkiat S. , Geber William F.
Published: June 2005

The teratogenic potential of a combination of chlordiazepoxide (Cdz) and amitriptyline (Amt) was examined with regard to both internal and external anomalies. Timed pregnant golden hamsters were given a single intraperitoneal injection on day 8 of gestation of one of the following: chlordiazepoxide hydrochloride (28.5 mg/kg), amitriptyline hydrochloride (70.3 mg/kg), Cdz‐Amt combination (28.5 mg/kg Cdz + 70.3 mg/kg Amt, in order to retain the 1:2.5 dose ratio utilized in a clinically‐used preparation of these agents), or saline vehicle (control). Fetuses were recovered on gestation day 15 following maternal sacrifice. Cranial malformations were analyzed in Bouin's‐fixed fetuses by making 1‐mm coronal sections through each head, whereas visceral anomalies were examined following general dissection of each body. Amt alone produced a significant (P < 0.05) incidence of bent tail and encephalocele, whereas Cdz significantly (P < 0.05) altered the male:female ratio of surviving fetuses when compared with saline‐injected controls. The Cdz‐Amt combination caused significant increases in cranial malformations, open eye, bent tail, abnormal lung, and urogenital anomalies. The teratogenic effects of potentiation between the components of this combination are discussed in terms of external and internal malformations.
The spontaneous occurrence of aortic arch and cardiac malformations in the White Leghorn chick embryo (Gallus domesticus)
Authors: Kuhlmann Randall S. , Kolesari Gary L.
Published: June 2005

Spontaneous aortic arch and cardiac malformations occur in White Leghorn chick embryos at a relatively high rate. Although this breed of Gallus domesticus is widely used for biomedical and biological research, no previous study has recorded the incidence of these defects. We found aortic arch malformations in 7.1% (14 of 196) and ventricular septal defects in 11.7% (23 of 196) of living embryos. Defects occurred alone or as a combined pattern. Our findings suggest that the cardiovascular defects in the chick embryo documented in past studies may, in some cases, have been part of normal spontaneous occurrence, rather than the major result of experimental manipulation.
Teratogenicity in swine of the tobacco alkaloid anabasine isolated from Nicotiana glauca
Authors: Keeler Richard F. , Crowe M. Ward , Lambert Edwin A.
Published: June 2005

Nicotiana glauca, wild tree tobacco, induces arthrogrypotic congenital defects in piglets similar to those induced by Nicotiana tabacum, common tobacco. The present work was conducted to isolate the principal alkaloid of N. glauca, anabasine, in large quantity and good purity and to test the teratogenicity of the compound in pigs. The isolated compound was established to be anabasine and to be of suitable purity by chemical characterization. It proved to be teratogenic. Typical arthrogrypotic defects were induced in 21 of 26 offspring (three of three litters) when dams ingested 2.6 mg of the compound per kg body weight twice daily during the 43rd–53rd days of gestation. Of three dams dosed with 1.66 g/kg/day of the dried plant material during the 43rd–53rd days, one delivered deformed offspring representing one‐third of all offspring in that group. These arthrogrypotic defects induced by anabasine were indistinguishable clinically from defects induced by either N. glauca or N. tabacum. In addition, anabasine at a dose of 2.6 mg/kg twice daily or N. glauca Plant material at 1.66 gm/kg daily induced cleft palate in over three‐fourths of offspring (100% of litters) when dams ingested either during the 30th–37th days of gestation or during longer periods that included those days.
Cardiac muscle development in mice exposed to ethanol in utero
Authors: Uphoff Cynthia , Nyquist‐Battie Cynthia , Toth Ronald
Published: June 2005

The purpose of the present research was to determine the effect of in utero ethanol exposure on cardiac muscle development. Pregnant albino mice (Swiss strain) at 8 days of gestation were divided into three groups: a normal group fed Purina lab chow for rodents and water ad libitum; an ethanol group fed the liquid diet ENSURE with 20% of the calories derived from ethanol (12.6 ± 1.2 gm/kg body weight per day); and an isocaloric group pairfed ENSURE with 20% of the calories derived from sucrose. These diets were continued until birth, at which time the litter size, crown to rump length, and weight were recorded. Randomly selected neonatal pups from each litter were decapitated and their hearts immediately processed for transmission electron microscopy. Litter size, crown to rump length, and body weight of the ethanol‐treated mice at birth were significantly less than normal but not less than pairfed controls. Ultrastructural evaluation of cardiac muscle from mice treated in utero with ethanol in comparison to that from both normal and pairfed control animals revealed various degrees of morphological alterations. The most pronounced alterations were in mitochondrial structure and included an increase in the amount of inner mitochondrial membrane. Myofibrillar abnormalities were also evident in the ethanol group but not in either control group. These abnormalities included a decrease in the myofibril volume per cytoplasmic volume and a disruption in myofibril organization particularly the Zbands. The ultrastructural alterations in the cardiac muscle from the ethanol treated group were not a result of malnutrition or dehydration as the pairfed group did not exhibit these changes. It is apparent from this study that exposure of mice in utero to ethanol can cause ultrastructural abnormalities in cardiac muscle cells. Whether these changes result in heart pathophysiology and persist to adulthood are not known.
Acetazolamide teratogenesis: Interation of maternal metabolic and respiratory acidosis in the induction of ectrodactyly in C57BL/6J mice
Authors: Weaver Timothy E. , Scott William J.
Published: June 2005

Exposure of C57BL/6J mice to 20% CO2 for 8 hours on day 10 of gestation has been shown to produce right‐sided postaxial forelimb ectrodactyly in 23% of the offspring. Carbon dioxide exposure produces a dramatic increase in maternal plasma CO2 accompanied by an inevitable decrease in plasma pH, both of which appear to be involved in the induction of ectrodactyly. However, the low incidence of ectrodactyly associated with NH4Cl‐induced metabolic acidosis suggests that the primary teratogenic factor in respiratory acidosis is elevated CO2 tension. This conclusion is supported by the observation that moderation of maternal plasma pH in the face of sustained elevated PCO2 fails to reduce the incidence of ectrodactyly; moreover, there is a strong correlation between maternal serum CO2 content and the incidence of ectrodactyly.
Control of nucleic acid and protein synthesis in developing brain, kidney, and heart of the neonatal rat: Effects of α‐difluoromethylornithine, a specific, irreversible inhibitor of ornithine decarboxylase
Authors: Slotkin Theodore A. , Persons Derek , Slepetis Ruta J. , Taylor Donald , Bartolome Jorge
Published: June 2005

Ornithine decarboxylase (ODC) and the polyamines are thought to play a role in maturation of mammalian tissues. Daily postnatal administration of α‐difluoromethylornithine (DFMO, a specific inhibitor of ODC) to newborn rats caused organ‐specific deficits in tissue weight gain, with brain and kidney as the major targets. Subnormal organ weights were associated with deficits in the levels of nucleic acids and proteins in the affected tissues, and examination of the synthetic rates of DNA ([3H]thymidine incorporation), RNA ([3H]uridine incorporation) and protein ([14C]leucine incorporation) confirmed that macromolecule synthesis was inhibited in DFMO‐treated pups. The time of onset of effect of DFMO on the synthesis of nucleic acids and proteins was the same as that reported for depletion of polyamines by this treatment. Potential adverse effects of DFMO on cell survival were also assessed by labeling DNA with [3H]thymidine on day 3 and examining retention of label 12 days later; DFMO did not cause an increase in cell death. In contrast to the sensitivity of brain and kidney to postnatally administered DFMO, development of cardiac tissue was relatively resistant to growth inhibition despite polyamine depletion. The organ specificity of effect of DFMO results, in part, from the different timetables for cellular events in tissue development displayed by each organ type; administration of DFMO earlier in development (during days 15 to 17 of gestation) did produce deficiencies in cardiac growth and nucleic acid levels similar to those which had been seen for brain and kidney. These data support the view that polyamines play a key role in cell replication, differentiation and growth during critical periods of mammalian organ development through their regulation of DNA, RNA, and protein synthesis.
Cervicovaginal abnormalities in BALB/c mice treated neonatally with sex hormones
Authors: Bern Howard A. , Mills Karen T. , Ostrander Patricia L. , Schoenrock Brian , Graveline Bryan , Plapinger Linda
Published: June 2005

Newborn female BALB/cCrgl mice received hormone treatments (daily for 5 days): 10−1 μg diethylstilbestrol (DES), 2 × 10−1 μg DES, 2 μg DES, 100 μg progesterone (P), 137 μg 17 α‐hydroxyprogesterone caproate, 10−1 μg DES + 100 μg P, 2 μg DES + 100 μg P, 5 μg testosterone (T), 20 μg T, 20 μg 5α‐dihydrotestosterone (DHT), or sesame oil and were examined at 25 days, 35 days, or from 10 to 30 days of age. Three major cervicovaginal abnormalities were noted: adenosis (heterotopic columnar epithelium) in the fornices; altered common cervical canal (aberrantly simplified cervical lumen), and twin fornix (lateral branching of either or both fornices). Only DES, administered alone or in conjunction with P, resulted in adenosis and altered common cervical canal. At 25 days, all mice given 2 × 10−1 μg DES showed adenosis. At 35 days, 75% of mice given 10−1 μg or 2 μg DES showed adenosis. Adenosis incidence following 10−1 μg DES was decreased by concomitant P. Altered common cervical canal was present in more than 90% of mice treated with DES alone at both 25 and 35 days; concomitant P lowered the incidence in mice receiving 10−1 μg DES. Neonatal exposure to endogenous prolactin from a pituitary transplant did not modify the response. Twin fornix was not evident 10 days after neonatal androgen treatment. The frequency increased significantly by day 15 of treatment, reaching 100% by day 20; incidence then declined to 86% and 63% on days 25 and 30 after treatment, respectively. Thus, neonatal sex hormone administration results in various cervicovaginal changes, some transient, decreasing with age in young mice.
The relationship between prenatal lethality or fetal weight and intrauterine position in rats exposed to diethylstilbestrol, zeranol, 3,4,3′,4′‐tetrachlorobiphenyl, or cadmium
Authors: Cornwall Gail A. , Carter Melvin W. , Bradshaw William S.
Published: June 2005

When administered orally during gestation, diethylstilbestrol (DES), zeranol (ZN), and 3,4,3′,4′‐tetrachlorobiphenyl (4CB) but not cadmium (Cd) exhibited significant developmental toxicity, including elevated embryoand fetolethality and reduced fetal weight, in Sprague‐Dawley rats. An analysis was performed to determine the effect of intrauterine position on these parameters. In control dams sacrificed after day 18, the general pattern was that fetuses at the ovarian end of the uterine horns were significantly lighter in weight, while the heavier fetuses were located in middle positions. Treatment with each of the chemicals reduced fetal weight equally across all uterine positions. An inverse of the weitht pattern was observed for prenatal mortality in controls. Embryonic resorptions were relatively more frequent at both ovarian and cervical ends, while conceptuses at intermediate positions were less vulnerable. No significant alterations in this pattern were observed in treated litters. The frequency of late fetal deaths in 4CB‐treated litters was significantly higher at the cervical end of the horn, however. No differences between horns or between sexes were observed in the relative position patterns for either weight or mortality.
The role of dysrhythmic heart function during cardiovascular teratogenesis in epinephrine‐treated chick embryos
Authors: Rajala Gregory M. , Kuhlmann Randall S. , Kolesari Gary L.
Published: June 2005

Chick embryos were treated with a teratogenic dose (5 μg) of epinephrine hydrochloride at 4 days of development (stage 24). Heart rates were determined at 20, 40, and 60 minutes after treatment. The mean heart rate values for epinephrine‐treated embryos were significantly less than values obtained for untreated and saline‐treated control embryos. The decrements in mean heart rate could be explained by severe cardiac dysrhythmias that occurred in approximately 40% of epinephrine‐treated embryos. The remaining 60% of embryos exhibited heartbeat patterns similar to controls. This finding enabled us to separate epinephrine‐treated embryos into two physiologically distinct groups: dysrhythmia‐positive and dysrhythmia‐negative. Dysrhythmias were characterized by periods of bradycardia alternating with periods of asystole and were confirmed by electrocardiography. EKG data suggest that epinephrine induces cardiac conduction disturbances in some chick embryos. An additional experiment was conducted to identify the frequencies at which abnormally obliterated aortic arches, abnormally persistent aortic arches, ventricular septal defects, and embryonic death occurred in dysrhythmia‐positive and negative embryos. Abnormally obliterated vessels and embryonic death occurred with significantly greater frequencies in dysrhythmia‐positive embryos. Abnormally persistent vessels and ventricular septal defects occurred with significantly greater frequencies in dysrhythmia‐negative embryos. We conclude that the production of specific malformtions and decreased probability for survival in epinephrine‐treated embryos are related to dysrhythmogenesis and bradycardia.
Growth and development of mice offspring after irradiation in utero with 2,450‐MHz microwaves
Authors: Berman Ezra , Carter Hershell B. , House Dennis
Published: June 2005

Mice offspring irradiated in utero with 2,450‐MHz radio‐frequency (RF) radiation at 0 or 28 mW/cm2 (whole‐body averaged specific absorption rate = 0 or 16.5 W/kg) for 100 minutes daily on days 6 through 17 of gestation were evaluated for maturation and development on days 1, 5, 10, 12, 15, and 17 of age. The tests used to determine differences in developmental age in the two treatment groups were body weight, urine concentrating ability, brain weight, tolerance to ouabain, and bone lengths. Fifteen sham‐irradiated and 26 RF‐irradiated litters, normalized to eight pups/litter, were used in this study. Mean body weight of the microwave‐irradiated offspring were significantly (p = .0003) decreased only on day 1 of age. Brain weight on days 10, 12, and 17 were significantly lower in microwave‐irradiated pups (p = .01). There were no significant differences in the two groups in urine concentrating ability on day 5, ouabain tolerance on day 15, or bone length on days 5, 10, 12, and 17. It is concluded that there is a persistent delay in postnatal development of the brain after RF irradiation with 16.5 W/kg during gestation.
Spontaneous and retinoic acid‐induced postaxial polydactyly in mice
Authors: Cusic Anne M. , Dagg C. P.
Published: June 2005

A spontaneous postaxial polydactyly, similar to type B in humans, was found in a partially inbred ICR mouse strain. The supernumerary digit could be detected grossly as early as day 14 of gestation. The incidence of polydactyly decreased with increasing gestational age. All‐trans retinoic acid (RA) administered on day 10 or 11 of gestation, but not on day 9, increased the incidence of polydactyly at each gestational day examined. The day 18 levels of polydactyly were greatest after day 10 treatment. No clear doseresponse relationship was observed in term fetuses following treatment on day 9, 10, or 11. RA administered on day 10 produced extra digits which were morphologically more advanced than those in the untreated controls. RA, given to the inbred C57B1/10 strain, produced low levels of polydactyly if administered on day 9, but not on day 10 or 11. F1 embryos, from reciprocal crosses between the two strains, were intermediate in response to RA. On day 14, cell death in the postaxial marginal mesoderm was apparent in all protopolydactylous embryos examined, whether treated or untreated. The supernumerary digits varied in size on day 14. The smaller digits appeared to be filled with necrotic mesodermal cells, whereas the larger digits had a necrosis‐free area. The size of the extra digit on day 14 seemed to be the most important factor in the persistence of the digit until day 18.
Differential dysmorphogenesis induced by microinjection of an alkylating agent into rat conceptuses cultured in vitro
Authors: Satish Jayavanthi , Pratt Bruce M. , Sanyal Mrinal K.
Published: June 2005

A technique of microinjection of small quantities of teratogens into extraembryonic compartments or specific organ primordium of rat conceptuses of pregnancy day 11 is described. Conceptuses microinjected with 50 nl tissue culture medium developed normally for 44–45 hr when cultured in homologous rat serum, indicating that the microinjection procedure itself did not produce any deleterious effects on growth and differentiation of embryos. Microinjection of an alkylating agent, phosphoramide mustard dissolved in tissue culture medium, into the exocoelom produced anomalous embryogenesis, consisting of retarded embryonic growth, anomalies of the neural tube, and general necrosis of various organ primordia. In contrast, the embryonic development remained relatively unaffected by microinjection of identical amounts of this alkylating agent into the amniotic cavity. However, neuraltube differentiation was markedly affected when phosphoramide mustard was injected into anterior neural‐tube fluid, producing anencephalic or microcephalic embryos without significant effect on postcephalic organ differentiation. The morphogenesis of the anterior limb was unaffected by local injection of the agent into somitic tissues adjacent to the presumptive limb‐bud region. Therefore, it appears that differential dysmorphogenesis could be induced by microinjection of an alkylating agent into different conceptus compartments. These results indicate that even during early embryogenesis various cell types are not equally susceptible to a given teratogen, and that the differential cytotoxicity of the teratogen toward specific embryonic or extraembryonic cells and tissues may account for embryonic anomalies characteristically produced by that agent.
Teratogenicity of dimethoxyethyl phthalate and its metabolites methoxyethanol and methoxyacetic acid in the rat
Authors: Ritter E. J. , Scott W. J. , Randall J. L. , Ritter J. M.
Published: June 2005

It is hypothesized that the known teratogen di(2‐methoxyethyl) phthalate (DMEP) acts by in vivo hydrolysis to 2‐methoxyethanol (2‐ME), also a known teratogen, which in turn is metabolized to methoxyacetic acid (MAA), the proximate teratogen. Teratological studies were conducted with Wistar rats, with the administration of these three agents on day 12 of gestation. On an equimolar dosage basis, DMEP, 2‐ME, and MAA were equally potent, which is consistent with the hypothesis. There was a striking similarity in the defects produced by these agents, mainly hydronephrosis, heart defects, and short limbs and tails. In particular all three agents produced unusual heart defects (dilated ductus arteriosus and dilated aortic arch) not seen with other agents, as well as ventral polydactyly, a rarely seen defect, suggesting teratogenic action by a common mechanism or component; 4‐methylpyrazole, an alcohol dehydrogenase inhibitor, provided significant protection against 2‐ME. This combination of effects strongly suggests that following the administration of DMEP, 2‐ME, or MAA, MAA is the proximate teratogen.