bluuebunny/crossref_metadata_2025 huggingface dataset:
Gonadal dysgenesis induced by prenatal exposure to ethinyl estradiol in mice
Authors: Yasuda Yoshiko , Kihara Takahide , Tanimura Takashi , Nishimura Hideo
Published: June 2005

Daily oral administration of ethinyl estradiol (0.02, 0.2, or 2.0 mg/kg of body weight) to pregnant Jc1:ICR mice resulted in ovotestis and intra‐abdominal testis with persistent Müllerian duct and Wolffian duct in male fetuses and ovarian hypoplasia in female fetuses when it was given from day 11 through day 17 of gestation (before gonadal differentiation in the fetus). The ovotestis consisted of testicular and ovarian portions. In the testicular portion, a few solid seminiferous tubules containing spermatogonia, some with pachytene nuclei with Sertoli cells and compact interstitial tissue including Leydig cells, were seen. In the ovarian portion, pachytene nuclei were seen. The intra‐abdominal testis was smaller and contained more spermatogonia per tubule in cross section than the control testis. These findings suggest that in male fetuses ethinyl estradiol affects Sertoli cell differentiation resulting in suppression of Müllerian inhibiting factor. On the other hand, in the ovarian hypoplasia, the primordial follicles and follicular cells in a primordial follicle were significantly decreased in number, and the number of the degenerated primordial follicles was significantly increased. It seems likely that ethinyl estradiol affects the intimate contact between follicular cells and oocytes to cause degeneration of primordial follicles.
The effects of 5‐bromodeoxyuridine on fusion of the cranial neural folds in the mouse embryo
Authors: Bannigan John Gerard
Published: June 2005

The effects of 500 and 300 mg/kg bromodeoxyuridine (BUdR) on the process of fusion of the neural folds were tested after injection into pregnant mice on day 8 of gestation (192 hours postcoitum). Various doses of the natural nucleoside, thymidine (TdR), were also tested. Both doses of BUdR retarded growth to the same extent, but only the larger dose caused neural tube defects in 28.8% of embryos. Treatment with the larger dose also caused extensive cell necrosis to appear in the neuroepithelium of the neural folds between 12 and 15 hours after treatment. No changes were detectable with the light microscope up to this time. Measurement of the cell generation time in treated and control embryos indicated that the BUdR prolonged the cycle by about 2 hours and that the dying cells were in the second DNA synthetic phase following incorporation of the analog. Treatment with the smaller dose of BUdR caused minimal cell necrosis. This was taken as evidence for the importance of cell necrosis in the pathogenesis of BUdR‐induced neural tube defects. Treatment with excess TdR did not cause either neural tube defects or cell necrosis, and a dose of TdR equimolar with the large dose of BUdR (400 mg/kg TdR) did not retard growth. Doses of 800 and 1,200 mg/kg TdR retarded growth to the same extent as BUdR. The administration of an equimolar amount of TdR, along with the teratogenic dose of BUdR, prevented the occurrence of cell necrosis and neural tube defects. When treatments were given on day 9 of gestation, 500 mg/kg BUdR caused cell necrosis in the neuroepithelium about 15 hours after treatment but no neural tube defects were produced by day 9 after treatment. It is suggested that in this case cell necrosis occurred too late to interfere with neural fold fusion. It was concluded that the ability of BUdR to cause exencephaly in mouse embryos was due to cell necrosis in the neuroepithelium.
Effects of acute exposures to elevated temperatures on rat embryo growth and development in vitro
Authors: Mirkes Philip E.
Published: June 2005

Day 10 rat embryos (8–12 somites) cultured in vitro were exposed to elevated temperatures (41–43°C) for varying lengths of time. A 15‐minute exposure to a temperature of 43°C (109.4°F) was sufficient to produce malformed embryos when observed on day 11. Longer exposures at this temperature produce higher incidences of malformed embryos and also more severely affected embryos. Temperatures of 42°C (107.6°F) or 41°C (105.8°F) also produced malformed embryos, but the required length of exposure was increased compared to 43°C. The minimal length of exposure at 42°C was 60 minutes, while at 41°C it was increased to 4 hours. The central nervous system was particularly sensitive to increased temperatures, and embryos exposed to “teratogenic doses” of hyperthermia exhibited primarily microcephaly and microphthalmia. In addition, histological analyses revealed that at 4.5 hours after a 30‐minute exposure to 43°C, necrotic debris was prevalent in the neuroepithelium, less prevalent in the surrounding mesenchyme and surface ectoderm, and absent in the tissues of the heart.
Ultrastructural analysis of malformations of the embryonic neural axis induced by in vitro hyperglycemic conditions
Authors: Reece E. Albert , Pinter Emese , Leranth Csaba Z. , Garcia‐Segura Miguel , Sanyal Mrinal K. , Hobbins John C. , Mahoney Maurice J. , Naftolin Frederick
Published: June 2005

Neural tube defects are the most common malformations associated with diabetic pregnancies. Although the teratogenic effects of excess glucose have been investigated in in vivo and in vitro studies, a cellular basis for neural tube defects has not been elucidated. We used rat embryo culture to study the organogenesis period of development, with excess d‐glucose added to the serum medium to induce neural tube anomalies. Light and electron microscopic examination of control 12‐day‐old embryos grown 48 hours in culture revealed blastlike cells with few organelles or cellular processes. Twelve‐day‐old embryos cultured in excess d‐glucose had advanced cellular maturation with differentiation, including the presence of free polysomes and copious cell processes, regardless of whether they had an open neural tube. Cytoarchitectural changes such as decreased numbers of mitotic figures with mitotic cells in the mantle layer were focally distributed throughout the neural epithelium but with predominance at the site of failed closure. In vivo studies failed to demonstrate neural processes in day 12 normal embryos. Fourteen‐day‐old embryos grown in utero also had foci of cell processes in the neural tube but to a much lesser degree than that observed in the in vitro day 12 glucose‐exposed embryos. The cellular aberrations in the excess d‐glucose‐treated embryos are characteristic of a premature maturational change. Since they are present in excess d‐glucose‐exposed embryos with or without failure of neural tube closure, these maturational and cytoarchitectural changes may contribute to the cellular basis for neural tube defects.
Maternal protein deprivation enhances the teratogenicity of ochratoxin a in mice
Authors: Singh Jarnail , Hood Ronald D.
Published: June 2005

Teratogenic effects of the mycotoxin ochratoxin A (OA) were investigated in protein‐deprived mice. Pregnant CD‐1 mice were assigned to control (26%), 16%, 8%, and 4% protein diet groups and treated by gavage with 0, 2, or 3 mg/kg OA on gestation day 8 (plug = day 1). They were killed on day 18 and subjected to teratological examination. OA treatment decreased prenatal survival, particularly at the two lowest dietary protein levels. OA at the higher dose also inhibited fetal growth in all groups, with a similar effect at the low dose in the 16% and 4% protein groups. Gross malformations associated with OA were inversely related to dietary protein levels; for example, 26% and 100% of the litters were affected in the 26% and 4% protein groups, respectively, at the high OA dose. A similar trend was also seen for skeletal malformations and variations. Thus maternal protein deprivation was seen to exacerbate adverse effects of OA in a developing mammal. Such results may have implications for areas where lack of adequate food supply may cause consumption of moldy grain by women or domestic animals already living on a protein‐deficient diet.
Cellular necrosis in zinc‐deficient rat embryos
Authors: Record I. R. , Tulsi R. S. , Dreosti I. E. , Fraser F. J.
Published: June 2005

Abnormal cellular necrosis was studied in 9.5–11.5‐day embryos obtained from zinc‐deficient rats. At periods of low maternal zinc status induced by a high intake of a zinc‐deficient diet, cell death was observed in those regions of the embryo that were most sensitive to teratogenic insult at that time. As the maternal serum zinc level increased during the fasting phase of the feeding cycle, the degree of necrosis decreased, leaving the tissue histologically more normal even though the embryos were grossly malformed. The mitotic index of cells in the neural epithelium and limb buds of zinc‐deficient, non‐necrotic embryos was found to be elevated, but there was no evidence of blockage at any particular stage of mitosis. It can be hypothesised that during the early stages of organogenesis, periods of low maternal zinc status initiate unscheduled cell death by some as yet undefined mechanism that in turn, gives rise to the morphological anomalies observed later.
Congenital bowing of long bones: Clinical and experimental study
Authors: Nogami Hiroshi , Oohira Atsuhiko , Kuroyanagi Masao , Mizutani Akira
Published: June 2005

The mechanism responsible for prenatal bowing of long bones was investigated based on the results of morphological observation and biochemical analysis of glycosaminoglycans of the autopsied bone from a newborn patient with classic campomelic dysplasia and the result of an experiment which produced a similar deformity in rat fetuses. An excised bone with postnatal bowing from a patient with osteogenesis imperfecta was also examined for comparison. In the case of campomelic dysplasia, marked hypertrophic change of the cambium layer of the periosteum at the concave side of the bone was noted. Parallel rays of the periosteal bone extended from the concave (posterior) side toward the apex of the bowing at the anterior side. Increased amounts and differences in composition of glycosaminoglycans were found in the diaphyseal bone on the concave side, suggesting the existence of bone with maturity retardation. In contrast, there were no such differences in the case with postnatal bowing and in the control. Congenital bowing of long bone in the patients with multiple malformations such as campomelic dysplasia is probably manifested as early as the cartilaginous model as the experimental result suggested.
The effect of prenatal exposure to the n‐butylester of 2,4‐dichlorophenoxyacetic acid (2,4‐D) on the immune response in mice
Authors: Blakley Barry R. , Blakley Patricia M.
Published: June 2005

Pregnant CD‐1 mice were administered the n‐butylester of 2,4‐dichlorophenoxyacetic acid (2,4‐D) by gastric intubation on day 11 of gestation at dosages ranging from 0 to 200 mg/kg (2,4‐D content). The immune response in the female offspring was elevated at 6 weeks of age. The humoral immune response, antibody production against sheep red blood cells, was not altered by 2,4‐D ester exposure during gestation. The mitogen responses of lymphocytes induced by concanavalin A, a T‐lymphocyte mitogen, or by Escherichia coli lipopolysaccharide, a B‐lymphocyte mitogen, were reduced in the highest exposure group (200 mg/kg), although the T‐lymphocyte suppression was not statistically significant. A similar response pattern was observed in the background nonstimulated lymphocyte cultures, suggesting that the suppression was a generalized lymphocyte abnormality. Evaluation of the mitogen responses using stimulation indices to correct for the variable background responses demonstrated that 2,4‐D produced no net suppressive effect in any of the treatment groups. Since in utero 2,4‐D ester exposure produced no alterations in humoral immunity and only subtle effects on lymphocyte blastogenesis, it is unlikely to be of any immunotoxicological or immunoteratological significance. Further studies investigating commercial‐grade 2,4‐D formulations are necessary since these formulations contain other components that may potentially induce alterations in the immune system.
Abnormal heart and great vessel development following acute ethanol exposure in mice
Authors: Daft Paula A. , Johnston Malcolm C. , Sulik Kathleen K.
Published: June 2005

Two maternal intraperitoneal doses of ethanol (2.9 g/kg) administered on gestational day (GD) 8, 12 hours (8d, 12h) and 8d, 16h result in abnormal heart and great vessel development in C57B1/6J mice. Heparinized hearts from GD 9 to 18 conceptuses were dissected to expose the forming or already completed ventricular septum and great vessels and then routinely processed for scanning electron microscopy. As early as GD 9 (12 hours post‐treatment), size deficiency and abnormal external contour of the cardiac tube were notable. By GD 12, deficiencies in the size of the conal and atrioventricular (A‐V) endocardial cushions, as well as abnormal positioning of the A‐V canal, were demonstrable. On GD 13, when the ventricular septum should be complete, a range of deficiencies in the conal tissue was observed. Deficiencies observed were a lack of closure of the ventricular septum in the region of the membranous septum, and lack of septation of the conal portion of the developing heart. These deficiencies persist and have been documented through GD 18. Other abnormalities noted on GD 18 include double‐outlet right ventricle, as well as distal defects of the great vessels including interrupted aortic arch, right aortic arch, and a vascular ring. While these defects are comparable to those seen in the fetal alcohol syndrome, they also overlap considerably with cardiac defects that are characteristic of those in the DiGeorge Syndrome as well as in the CHARGE Association. Recent work by others as well as the fact that acute ethanol exposure in this animal model corresponds to a time of neural crest cell migration has led to the speculation that this cell population is involved in the cardiovascular pathogenesis described.
The toxicity of niridazole in rat embryos in vitro
Authors: Fantel A. G. , Greenaway J. C. , Walker E. , Juchau M. R.
Published: June 2005

The antischistosomal drug niridazole (NDZ) was found to be teratogenic in a concentration‐dependent manner from 10 to 50 μg/ml (47–233 μM) in rat embryos cultured from day 10 to day 11. A striking malformation consisting of axial asymmetry in which the right side of the embryo showed severe necrosis was the predominant malformation. The drug showed significantly greater dysmorphogenic activity at low (5%) compared to high (20%) oxygen tensions in cultures. Coincubation of embryos and NDZ with an exogenous source of metabolic enzymes and cofactors (NADPH) failed to modify teratogenicity. Inclusion of CO in the culture atmosphere significantly reduced the malformation incidence as did preincubation of the drug with S‐9 and cofactors in medium with low O2 tension. Treatment of gravida with NDZ up to and including the maternal‐lethal dose failed to result in observable malformations despite the use of several routes of exposure. These data lead us to hypothesize that rat embryos are capable of performing the reductive activation of NDZ in a fashion analogous to the schistosome but that reductive extraembryonic metabolism may result in teratogenic bioinactivation.
Pulmonary stenosis with ventricular septal defect, common aorticopulmonary trunk, and dextroposition of the aorta: Morphologic and qualitative physiologic effects in caffeine‐treated chick embryos
Authors: Bruyere Harold J. , Nishikawa Toshio , Uno Hideo , Gilbert Jennifer E. , Gilbert Enid F.
Published: June 2005

Effects of caffeine administration to Hamburger‐Hamilton stage 19 chick embryos (3 days of incubation) were investigated. A morphologic study of the effect of caffeine on cardiogenesis showed that caffeine produced total cardiac malformations in the chick in a dose‐related fashion. A maximum frequency of 70.6% was observed with 4.7 mg caffeine. Major malformations included common aorticopulmonary trunk and dextroposition of the aorta accompanied by ventricular septal defect with/without pulmonary stenosis. Qualitative analysis of cinegraphs following exposure of embryos to a single teratogenic dose of caffeine (3.5 mg/egg) produced marked alterations in cardiac function when compared with chick Ringer's controls. Within 3 minutes after exposure to caffeine, dilation of the common ventricle and weak ventricular contractility were observed and persisted for 1 hour. Dose‐response data and microcinematographic observations suggest that caffeine induced cardiac anomalies by a direct toxic effect on the embryo rather than by altering cardiac cell function. Our data also suggest that pathophysiologic changes in cardiac function may play an important role in the pathogenesis of caffeine‐induced cardiac anomalies in the chick embryo.
Toxic and teratologic effects of verapamil on early chick embryos: Evidence for the involvement of calcium in neural tube closure
Authors: Lee H. , Nagele R. G.
Published: June 2005

Toxic and teratologic effects of verapamil, a calcium antagonist, on chick embryos explanted at stage 8 (four‐somite stage) and cultured for 6–8 hours were investigated. In general, embryos responded to verapamil in a dose‐related manner. Concentrations lower than 2 μg/ml had no apparent effect on the development of embryos. A concentration of 15 μg/ml significantly increased the incidence of embryos (approximately 80% of viable embryos) with neural tube closure defects and less numerous somites. Higher concentrations (e.g., 30 μg/ml) were embryotoxic and over 90% of the embryos were either severely malformed or dead after 8 hours of incubation. Compared to controls, verapamil‐treated neuroepithelial cells had smoother apical surfaces and less conspicuous microfilament bundles. The deleterious effects of verapamil (15 μg/ml) could be reversed by subculturing the affected embryos, within 3 hours of treatment, on nutrient medium alone or on nutrient medium containing 25 μg/ml chlorotetracycline (CTC), a calcium agonist, the latter being more effective provided that treatment did not exceed 4 hours. Exposure of the developing neuroepithelium to 15 μg/ml verapamil for 3–4 hours resulted in a significant reduction in free Ca2+ levels, as revealed by the pyroantimonate precipitation method, throughout neuroepithelial cells. Overall results suggest that verapamil causes neural tube closure defects by reducing intracellular free Ca2+ levels, thereby relaxing apical microfilament bundles of developing neuroepithelial cells.
Effects of methylmercury and mercuric chloride on preimplantation mouse embryos in vivo
Authors: Kajiwara Yuji , Inouye Minoru
Published: June 2005

This report compares the effects of methylmercuric chloride (MMC) and mercuric chloride (MC) on the development of mouse preimplatation embryos in vivo. Female mice were injected with a single intravenous dose of 0.5–20.0 mg Hg/kg MMC or 0.5–2.5 mg Hg/kg MC on day 0 of gestation. The embryos were recovered by flushing excised oviduct and uterus on day 3.5 of pregnancy, and were examined for abnormalities. In the groups treated with doses of 0.5 and 1.0 mg Hg/kg of both compounds, the rates of abnormal embryos were not significantly different from that in the control group. The 50% effective dose of MMC was twice as great as that of MC. With increasing dose, the difference became more obvious; the 80% effective doses differed by a factor of ten. The body weight of dams decreased in terms of the dose of mercury in MC‐treated groups, but did not vary in MMC‐treated groups. The sensitive developmental stage for mercury toxicities could not be determined clearly, although the high sensitivity was reported in the blastocyst stage in vitro. The embryos treated in vivo were less sensitive than those reported in vitro.
Seasonal variation of neural tube defects in Newfoundland and elsewhere
Authors: Fraser F. C. , Frecker M. , Allderdice P.
Published: June 2005

In Newfoundland, babies with anencephaly are conceived most often in January, and those with spina bifida in August. These and previous observations suggest that (1) seasonal fluctuations are greatest when the population frequency is neither very high nor very low, and that (2) the peak season for conception of anencephalic babies may occur in any season except August‐November in various populations, whereas for spina bifida seasonal peaks are confined almost exclusively to May–August.
Effect of mitomycin C on the neural tube defects of the curly‐tail mouse
Authors: Seller Mary J. , Perkins Kathleen J.
Published: June 2005

Around 60% of the mouse mutants called curly‐tail, have tail aberrations in the form of a coil or a kink, with or without lumbosacral spina bifida, and rarely, exencephaly. These neural tube defects (NTD) are the result of an incompletely penetrant recessive gene. A single injection of various doses (1–6 mg/kg) of the DNA inhibitor mitomycin C was given to pregnant curlytail mice on day 7, 8, or 9 of gestation, and its effect on the NTD of the embryos was noted. No dose used was lethal to the embryo. When given on day 7 or day 8, mitomycin C markedly increased the number of exencephalics, and additionally, on day 8, it reduced the number of posterior abnormalities. However, on day 9, no exencephaly was produced, and there was a drastic reduction in the number of tail and spinal defects, the overall incidence of NTD being as low as 15% with 2 mg/kg. A twofold effect of mitomycin C on the curly‐tail embryos was thus observed–according to the time in development it was administered, firstly, a teratogenic effect, and later, a “remedial” or preventive effect.
Experimental congenital disease with simian cytomegalovirus in rhesus monkeys
Authors: London W. T. , Martinez A. J. , Houff S. A. , Wallen W. C. , Curfman B. L. , Traub R. G. , Sever J. L.
Published: June 2005

Cytomegalovirus (CMV) infections occur worldwide and are responsible for severe damage to the child in from one to five newborns per 20,000 births. Animal models of congenital CMV infection resulting in disease have been developed in mice and guinea pigs. We report here the development of ventricular dilatation and leptomeningitis in rhesus monkeys, Macaca mulatta, following intrauterine infection with rhesus cytomegalovirus (RCMV). Central nervous system (CNS) lesions were associated with low cytomegalovirus fluorescent antibody titers in affected fetuses. In several infected animals, RCMV was isolated at necropsy from neural and nonneural tissues taken shortly after birth. This model allows investigators to study the pathogenesis and prevention of CNS changes following RCMV infection.
Inconsistent use of terminology in animal developmental toxicology studies: A discussion
Authors: Black Daniel L. , Marks Thomas A.
Published: June 2005

The usage and meaning of terminology in teratology studies varies from laboratory to laboratory. This variability often causes confusion on the part of those reading and attempting to interpret the results published in papers and technical reports. Terms often used to categorize individual findings include embryotoxicity, fetotoxicity, teratogenicity, and maternal toxicity. One reason for the variability in the meaning of these words may be the inconsistency in the categorization of data leading up to the interpretation of the results. A more standardized use of these terms would allow more consistent interpretation and comparision of the data presented in teratology reprots. This communication discusses some of these inconsistencies and offers suggestions that might help improve the situation.
Social play in juvenile rats prenatally exposed to alcohol
Authors: Meyer Linda S. , Riley Edward P.
Published: June 2005

Offspring of rat dams that consumed isocaloric liquid diets containing either 35% or 0% ethanol‐derived calories (EDC) from gestation days 6–20 were tested for play‐fighting behavior as juveniles. Offspring from a group of dams maintained on standard lab chow and water throughout gestation were also included. Animals were tested in pairs, with offspring from each of the three prenatal treatment conditions (35% EDC, 0% EDC, and lab chow) being paired with another same‐sex animal from one of these three prenatal treatment groups. Although play‐fighting in juveniles is normally sexually dimorphic, this normal pattern was absent in juveniles prenatally exposed to alcohol. Male alcohol‐exposed offspring displayed feminized behavior while female alcohol‐exposed offspring showed masculinized behavior. This reversal of the normal sexually dimorphic aspects of play suggests that some of the behavioral disturbances associated with prenatal alcohol exposure may result, in part, from an alcohol‐induced disruption of the hormonal environment in which the fetus develops.
The antiestrogen LY117018 is estrogenic in the fetal rat
Authors: Henry Ellen C. , Miller Richard K.
Published: June 2005

LY117018 (LY) has high affinity for the adult rat uterine estrogen receptor, has little uterotrophic activity, and inhibits many estradiol (E2)‐induced responses in the adult or immature uterus. In these studies, LY was injected into day 19 rat fetuses, with and without diethylstilbestrol (DES) or E2, to determine whether it could block the estrogen‐induced teratogenesis. LY at 1, 25, or 50 μg/fetus failed to decrease the 15–70% incidences of oviduct malformation and cleft phallus induced by DES (2.5 μg/fetus) or E2 (50 μg/fetus). However, LY alone (1‐50 μg/fetus) was more potent than E2 in eliciting these same urogenital malformations. LY also failed to compete in vitro for plasma protein‐bound 3H‐E2, and therefore, like DES, is more available than E2 for uptake into fetal tissues. Thus, in the fetus, unlike the adult, LY was an estrogen agonist, which indicates that the fetus has a very different sensitivity than the adult to estrogenic compounds.
Stereomicroangiography in embryologic and teratologic investigation
Authors: Effmann Eric L. , Whitman Sandra , Pexieder Tomas
Published: June 2005

Vascular dysmorphogenesis is usually investigated by invasive microdissection or time‐consuming reconstruction of serial sections. Stereomicroangiography (SMA) was used for detection and analysis of vascular abnormalities in a murine trisomy 13 model demonstrating pulmonary atresia. Twenty‐two litters from doubly heterozygous Robertsonian translocation Rb(6.13)3Rma/Rb(5.13)70Lub male matings to NMRI females were studied. Embryos (13–17 days gestation) were prepared by umbilical vein perfusion with buffered fixative and umbilical artery perfusion with 5% AgNO3. After immersion fixation specimens were infiltrated with paraffin, mounted on stubs, and stereoradiographed at multiple angles. Transverse serial sections were prepared of the thoracic area. Thoracic vascular morphology was satisfactorily imaged and trisomy 13 embryos were correctly distinguished from normals in 105 of 120 embryos (87.5%). When independent SMA and histologic interpretations were compared anomalous vasculature was correctly identified in all 27 trisomic embryos and one control, and falsely interpreted in one normal embryo. Normal vascular morphology was demonstrated in the remaining 76 normal embryos. Separate SEM evaluation of five microdissected hearts from nontrisomic embryos following this perfusion schedule showed normal distension of the ventricular cavity and metallic silver deposition on the surface and at junctions of endocardial cells. Light microscropy revealed silver staining at the endothelial surface and within the endocardial cushions. SMA accurately records embryonic vascular morphology for rapid screening of viable embryos.
Exogenous sex hormone exposure and the risk for VACTERL association
Authors: Lammer Edward J. , Cordero Jose F. , Khoury Muin J.
Published: June 2005

In several studies investigators have suggested that maternal use of exogenous sex hormones during early pregnancy may be associated with various congenital malformations. A group of malformations, the VACTERL (vertebral, anal, cardiac, trachea, esophageal, renal, limb—acronym) association, has been statistically associated with maternal exposure to exogenous sex hormones during the first trimester of pregnancy. The VACTERL association is a nonrandom group of major malformations that occur together more often than would be expected on the basis of chance. To assess this association, we conducted a case‐control study of first‐trimester exposure to sex hormones among mothers of 34 infants with the VACTERL association and of 1,024 comparison infants with one or more of ten major malformations or Down syndrome. The study subjects were malformed infants born between July 1970 and June 1979 and registered in a population‐based birth defects registry. Information concerning the use of exogenous sex hormones during pregnancy was obtained by systematically interviewing the mothers of the malformed infants. Most of the mothers were interviewed within 6 months of their children's births. Each mother was interviewed within a year of her child's birth. We found an odds ratio of 0.98 (90% confidence limits 0.40, 2.38) for the relationship between VACTERL association and use of any sex hormone in the first trimester of pregnancy. Our study had adequate statistical power to detect a true relative risk of 2.8 or greater.
Teratogen concentration changes as the basis of the heat stress enhancement of arsenate teratogenesis in hamsters
Authors: Hanlon David P. , Ferm Vergil H.
Published: June 2005

Hamster dams dosed continously with arsenate and exposed to short‐term hyperthermia produced a greater percentage of malformed offspring than did hamster dams dosed with arsenate alone. Hamsters receiving both treatments possessed elevated arsenic concentrations in the maternal blood and placentas immediately after cessation of the hyperthermic insult. Blood levels of arsenic were the same as those of animals not receiving the heat treatment within several hours post‐hyperthermia; however, arsenic concentrations remained elevated in placentas, the duration being dependent on the dose of arsenate. We suggest that the rise in placental arsenic concentrations is the basis of the increase in the production of fetal malformations for hamsters treated continuously with arsenate and heat stressed during critical organogenesis.
Strain differences in response of Sprague‐Dawley and Long Evans Hooded rats to the teratogen nitrofen
Authors: Kang Y. J. , Zolna L. , Manson J. M.
Published: June 2005

Administration of nitrofen (2,4‐dichloro‐4′‐nitrodiphenyl ether) during organogenesis in rodents produces neonatal lethality accompanied by lung hypoplasia, diaphragmatic hernias, heart anomalies, and hydronephrosis. Different strains of rats, Long Evans Hooded (LEH) and Sprague‐Dawley (SD), are reported to have different malformation responses to prenatal exposure, which could be due to true strain differences, to different levels and times of exposure, or to the use of different methods for detecting visceral malformations. In the present study, LEH, SD, and „virus‐antibody‐negative”︁ SD (VAN‐SD) rats were identically exposed to 0, 6.25, 12.5, or 25 mg/kg/day of nitrofen by gavage in corn oil on days 6–15 of gestation. At term, half of the litter was examined by the Wilson method of razorblade sectioning and the remainder by a modified Staples method of fresh visceral examination. The two methods were equally sensitive for detecting diaphragm, kidney, and lung anomalies, whereas heart malformations were more frequently identified with fresh visceral examination. The frequency of total malformations did not vary across strains at any dose, but there were substantial differences in the pattern of malformations in each strain. SD and VAN‐SD rats responded similarly for all malformations, but had significantly higher incidences of diaphragm and lung anomalies than LEH rats. Conversely, LEH rats had significantly elevated levels of kidney anomalies compared to SD and VAN‐SD rats, whereas frequency of heart malformations was low and comparable across strains. These results suggest that true strain differences exist in the pattern of malformation produced by prenatal exposure to nitrofen that may be based on genetic differences in embryonic susceptibility.
Teratogenicity of paraxanthine (1,7‐dimethylxanthine) in C57BL/6J mice
Authors: York Raymond G. , Randall Joan L. , Scott William J.
Published: June 2005

The teratogenicity of caffeine, as well as two of its three dimethylated metabolites (theobromine and theophylline), has been established in animal studies. The third metabolite, paraxanthine, has not been reported as being tested for teratogenicity even though it is actually the major demethylated metabolite of caffeine metabolism in man. Pregnant C57BL/6J mice were treated i.p. with 175 or 300 mg/kg/day paraxanthine (1,7‐dimethylxanthine) dissolved in deionized water at 4 p.m. on day 11 and 9 a.m. on day 12 of gestation. All dams were sacrificed on day 18, and fetuses were fixed for Wilson's razor blade sectioning or double‐staining skeletal examination. A dose‐related increase in total malformations, primarily cleft palate and limb malformations, was found. The pattern of malformations was similar to that reported for caffeine, theobromine, and theophylline, i.e., an asymmetric response with the left forelimb most often affected. A 21% resorption and a 46% malformation rate was observed at 300 mg/kg/day of paraxanthine, indicating that paraxanthine was slightly less toxic to the embryo than caffeine. Therefore, the parent compound, caffeine, as well as all three of its dimethylated metabolites—paraxanthine, theophylline, and theobromine—are teratogenic.
In vitro studies on the effect of yolk sac antisera on functions of the visceral yolk sac: I. Pinocytosis and transport of small molecules
Authors: Lerman S. , Koszalka T. R. , Jensen M. , Andrew C. L. , Beckman D. A. , Brent R. L.
Published: June 2005

The production of congential malformations by the administration of teratogenic antisera to pregnant animals has been reported from many laboratories. This work has focused our attention on the importance of the yolk sac placenta in supporting the rat embryo during early organogenesis and the significance of yolk sac dysfunction in rodent teratogenesis. The studies reported in this article deal with the effect of teratogenic antisera on the process of yolk sac transport; specifically pinocytosis (as measured by 14C‐sucrose uptake) and small‐molecule transport utilizing 14C‐α‐aminoisobutyric acid (AIB) and 3H‐2‐deoxyglucose (DOG). We sought to determine whether several different yolk sac localizing antibodies interfere with these transport processes, and, if so, which transport processes were most affected.

The results of the experiments indicated that teratogenic antisera interfered with the process of pinocytosis in the yolk sac and that pinocytosis can be reduced as much as 40%. Nonteratogenic antisera, even when they localized in the yolk sac, did not interfere with the process of pinocytosis. Furthermore, the teratogenic antisera did not interfere with the transport of small molecules (either AIB or DOG) in the yolk sac. These results indicated that while fluorescent localization of an antiserum in the yolk sac did not invariably indicate the potential for teratogenicity, it is likely that the reduction in pinocytosis may directly correlate with the teratologic and embryopathic events. This work reaffirms the view that the yolk sac in important during rodent organogenesis and that yolk sac dysfunction can play an important role in the development of congenital malformations. The results from the endocytosis experiments with explanted yolk sacs did identify the embryotoxic antiserum (i.e., whole visceral yolk sac antiserum) and thus this method may have utility as a rapid bioassay for these antisera. The simple measurement of endocytic index as a marker for the determination of teratogenicity of uncharacterized sera would represent a considerable saving in time, effort, and animals.
Dose‐ and stage‐related sex difference in the incidence of cytosine arabinoside induced digit anomalies in the mouse fetus
Authors: Goto Tadashi , Endo Akira
Published: June 2005

Pregnant mice of the Jc1:ICR strain were injected intraperitoneally with a single dose of 2.5, 5, or 10 mg/kg of cytosine arabinoside (Ara‐C) on day 9.5 or 10.5 of gestation (dg). Mice were killed on 18.4 dg, and the incidences of digit anomalies were compared between male and female fetuses. In the group treated with 10 mg of Ara‐C on 9.5 dg, oligodactyly of the hindlimbs was produced more frequently in male fetuses. In the group treated with 5 mg of Ara‐C on 10.5 dg, oligodactyly of the forelimbs tended to occur more frequently in male fetuses. Also, in this group, oligodactyly of the hindlimbs occurred more frequently in male fetuses, whereas polydactyly occurred more frequently in female fetuses. The observed difference in the incidences of digit anomalies between male and female fetuses may be explained either in terms of the sex‐related time lag in the critical period for digit development or by a probable sex difference in embryonic susceptibility to Ara‐C.
Glycolysis in the mouse uterus during the early post‐implantation stages of pregnancy and the effects of acute doses of ethanol
Authors: Murdoch R. N.
Published: June 2005

The objective of this study was to assess the possibility that, in mice, alcohol interferes with uterine glycolysis to influence indirectly embryonal development. Glycolysis was found to be a major metabolic process in the mouse uterus and its pattern of activity changed during post‐implantation pregnancy between days 5 and 9. This was evidenced by changes in glycolytic enzymes and intermediates, and in the capacity of endometrial preparations to consume oxygen and produce lactate during incubation in vitro. The intraperitoneal administration of ethanol at 3.0 and 6.0 gm/kg body weight, but not at 1.5 gm/kg body weight, on day 9 of pregnancy modified glycolysis in the uterus after 2 hours, resulting in significant changes in the rates of accumulation of glucose, glucose‐6‐phosphate, fructose‐6‐phosphate, fructose‐1,6‐diphosphate, and citrate. These effects were not mediated by changes in redox state, since the ratio of lactate to pyruvate remained unchanged after injection of ethanol. Citrate was considered to be a major factor involved both in the regulation of uterine glycolysis and in the ethanol‐induced alterations in the levels of hexose phosphates. The elevated levels of uterine glucose registered after treatment with ethanol were related to an acceleration of glycogen degradation in the liver and not in the uterine endometrium. The results suggest that part of the adverse action that these doses of ethanol exert on embryonal development stems from indirect effects that involve uterine functions relating to the nurture of the conceptus via glycolysis.
Assessment of the safety of chemicals administered intravenously in the neonatal rat
Authors: Greener Yigal , Gillies Barbara , Wienckowski David , Schmitt Donald , Woods Eugene , Youkilis Eugene
Published: June 2005

A 3‐day‐old neonatal rat model for the safety assessment of various drugs, chemicals, and nutrients administered intravenously is described. This model was used to assess the safety of di(2‐ethylhexyl) phthalate (DEHP), cyclohexanone, and a 3:1 mixture of medium and long‐chain triglyceride emulsions following subchronic administration using the intravenous route. The administration of DEHP at dosage of 164.8 mg/kg for 18 consecutive days resulted in a small but statistically significant increase in liver weight and SGOT activity. However, no conclusive histopathological alternations could be discerned between livers from DEHP and normal saline (control) animals. No effects were observed among neonates treated with cyclohexanone at dosages up to 25 mg/kg for 18 consecutive days. Because of technical difficulties emanating from high dosage volumes, the administration of lipid emulsion mixture lasted 9 consecutive days only. Except for transient ataxia and sedation, no adverse effects were observed among neonates that received 3:1 medium‐ and long‐chain triglyceride emulsion for 9 consecutive days beginning on day 3 postpartum. No adverse effects were observed among neonates receiving the lipid emulsions for 7 consecutive days beginning on day 12 postpartum.
Aspirin and acetaminophen use by pregnant women and subsequent child IQ and attention decrements
Authors: Streissguth Ann Pytkowicz , Treder Robert P. , Barr Helen M. , Shepard Thomas H. , Bleyer W. Archie , Sampson Paul D. , Martin Donald C.
Published: June 2005

In a longitudinal prospective study of 1,529 women pregnant in 1974–1975, aspirin and acetaminophen were the two medications most frequently taken during the first half of pregnancy (46 and 41%, respectively). In a selected cohort of 421 offspring of these women, examined at 4 years of age, maternal aspirin use during the first half of pregnancy was significantly related to IQ and attention decrements in the exposed children. Multiple regression analyses were used to statistically adjust for a variety of potentially confounding factors including demographic characteristics, child characteristics, other exposures, and lifestyle/environmental variables. Continuous doseresponse and step‐function parameterizations of aspirin exposure were both statistically significant and not clearly distinguishable from each other. The estimated aspirin effect is significantly greater, for girls than boys. Aspirin effects on offspring function were found in the absence of effects on physical size both at birth and at 4 years. Maternal acetaminophen use was not significantly related to child IQ or attention. As this exploratory research originated from observations of a data set gathered for other purposes, it would be desirable to have these findings replicated in other studies. Further follow‐up of the children at a later age is planned.
Inhibitory effect of caffeine on 5‐azacytidine‐induced digital malformations in the rat
Authors: Kurishita Akihiro , Ihara Toshio
Published: June 2005

The effect of caffeine on 5‐azacytidine (5‐AC)‐induced digital malformations in rat fetuses was investigated. Caffeine suppressed all types of digital defects in the fore‐ and hindlimbs except for syndactyly induced by 1.0 mg/kg of 5‐AC; it was still effective when administered 24 hours after 5‐AC treatment. However, fetal mortality increased as the frequency of malformations decreased. While the malformation results support the view that caffeine inhibits the processes leading to malformation expression, the relation between its suppressive effect on malformations and its enhancing effect on fetal mortality is unclear.
Uterine trauma and limb defects
Authors: Webster William S. , Lipson Anthony H. , Brown‐Woodman Patricia D. C.
Published: June 2005

The temporary clamping of the uterine blood vessels on one side of the uterus during late pregnancy in the rat (days 14–16) results in hemorrhage and tissue necrosis in the extremities of the fetuses from the experimental side and occasionally from the control side. A further series of experiments showed that similar fetal hemorrhage followed 1) the temporary clamping (45 minutes) of the uterine wall or uterine fat, excluding major uterine vessels; 2) handling the uterus for 5 minutes; and 3) stretching of the uterine blood vessels. A low incidence of fetal hemorrhage was also associated with laparotomy alone, but the fetuses were unaffected by extensive handling of the uterus through the abdominal wall or by intraperitoneal anesthesia. Fetal hemorrhage was also induced by a short episode of severe maternal hyperthermia but not by a high dose of ethanol given by gavage. These results suggest that a range of uterine trauma may result in fetal hemorrhage, perhaps through a common mechanism.
Maternal smoking: Greater effect on males, Fetal Tobacco Syndrome?
Authors: Wertelecki Wladimer , Hoff Charles , Zansky Shelley
Published: June 2005

We tested the recently proposed criteria for a Fetal Tobacco Syndrome (FTS) on a sample of 925 primiparous black women (including 204 smokers) and their neonates. The proposed FTS criteria included proportional growth retardation (ponderal index > 2.26, birth weight < 2,500 g) in term neonates. Only 19 neonates (2%) in our study fulfilled the FTS morphometric criteria, and of these only 8 had smoking mothers. Nonetheless, the negative effect of maternal smoking on fetal growth (birth weight and length) as reported from earlier investigations was clearly evident in our own data (P < .01). Separate analysis by fetal sex revealed that the negative effect of maternal smoking upon fetal growth is more pronounced among males than females. We concluded that fetal sex should be taken into account in studies of maternal smoking effects. As for evidence for the existence of the FTS, it remains to be proven.
Pregnancy outcomes after weekly oral administration of ethanol during gestation in the pig‐tailed macaque (Macaca nemestrina)
Authors: Clarren Sterling K. , Bowden Douglas M. , Astley Susan J.
Published: June 2005

Ethanol was orally administered once per week to gravid pigtailed macaques (Macaca nemestrina) in doses of 0.3, 0.6, 1.2, 1.8, 2.5, 3.3, or 4.1 g/kg. A control group received a sucrose solution, isocaloric and isovolemic to the highest ethanol dose. Pregnancy was followed after 116 possible conceptions in 54 females. Peak plasma ethanol concentrations (PPECs) ranged from 24 ± 6 mg/dl at the 0.3 g/kg dose to 549 ± 71 mg/dl at the 4.1 g/kg dose. An increased rate of spontaneous abortion was related to ethanol exposure at and above 1.8 g/kg (mean PPEC = 205 mg/dl). Pregnancy failure in the first 30 days of gestation increased at doses above 2.5 g/kg. The effect on pregnancy outcome of weekly exposure to ethanol in this nonhuman primate is comparable to available data on humans. The methodology of this study represents an effective model for studying ethanol teratogenesis in a nonhuman primate.
Developmental anomalies induced by all‐trans‐retinoic acid in fetal mice: II. Induction of abnormal neuroepithelium
Authors: Yasuda Yoshiko , Konishi Hiroyoshi , Kihara Takahide , Tanimura Takashi
Published: June 2005

All‐trans‐retinoic acid (RA) in olive oil was given in doses of 0, 40, or 60 mg/kg of body weight to pregnant mice on day 8 of gestation, and 2–6 hr later embryos were fixed in solutions with or without cetylpyridinium chloride (CPC). The neuroepithelium of the presumptive midbrain was processed for light and electron microscopy. Distorted contours of the neuroepithelium were induced by both doses of RA and the incidence and the severity of the disorganized neuroepithelium showed dose‐related results. Abnormal neuroepithelium showed wide intercellular spaces with degenerated cytoplasmic processes or cell debris, separation of the apical side from adjacent cells, retention of mitotic and/or postmitotic cells on the apical side, presence of mitotic cells on the basal side, and detachment of degenerated structures from the neuroepithelium. Ultrastructurally, the affected neuroepithelium showed (1) appearance of degenerating filamentous or tubular coagulating bundles in the cytoplasm and the cytoplasmic process of the neural crest cells, (2) dispersal of polysomes into monosomes especially in the degenerating neural crest cells, (3) and a collecting of microfilament‐like structures at the contact area between the neural crest cell and the presumptive neuroblast. These morphological changes suggest that RA affects the nature of cytoskeletal elements and the protein synthesis of the neuroepithelial cells. The selective susceptibility of neural crest cells to RA causes more degenerating neural crest cells in the neuroepithelium, which causes nonapproximation of the neural folds and scantiness of the migrating neural crest cells; these results lead to neural tube defects and craniofacial anomalies, respectively.