bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of diazepam on meiosis in the CF‐1 mouse
Authors: Stenchever Morton A. , Smith W. Dianne
Published: June 2005

Oocytes from virgin CF‐1 female mice were treated in vitro with Krebs‐Ringer media containing 1.0, 10.0, 30.0, 50.0, 100.0, and 200.0 μg/ml of diazepam. In addition, oocytes were exposed to no drug and to 4% propylene glycol and Krebs‐Ringer media. The latter was chosen because diazepam is frequently injected in a propylene glycol vehicle. After 17 hours of incubation at 37°C in a 5% C02 atmosphere, all oocytes were scored for the presence of germinal vesicles, Metaphase I, Metaphase II, or degenerative and abnormal forms. Cells from the pure control, propylene glycol, 1.0, and 10.0 μg/ml concentration preparations demonstrated progress to Metaphase II in from 86–89% of cells. Only a small percentage of oocytes was noted to be degenerative or abnormal in any of these groups. From 0.6–2% of oocytes were arrested in Metaphase I. At 30.0 μg/ml concentration 18.7% of cells were arrested at Metaphase I but only 1.5% were noted to be degenerated. At 50.0 μg/ml, 26.6% of cells were arrested at Metaphase I and 13.3% were degenerated. At 100.0 μg, 7.7% of cells were found in Metaphase I, 9.2% in Metaphase II, and 67.7% degenerated. At 200.0 μg/ml 3.1% of cells were found at Metaphase I, none at Metaphase II, and 88% in the degenerative form. Since blood levels of diazepam rarely rise above 6 μg/ml even in patients treated with as much as 200 mg per day, and are generally observed in the 1 μg/ ml range for patients on typical treatment regimen, it is not likely that human tissues will achieve concentrations seen to have toxic effects in these studies. Future in vivo studies, however, seem indicated.
Teratogenic effects of mescaline, epinephrine, and norepinephrine in the hamster
Authors: Hirsch Kenneth S. , Fritz H. Ira
Published: June 2005

Mescaline was administered orally at doses of 16 and 32 mg/kg on the seventh through tenth days of gestation to pregnant cream‐strain hamsters. This treatment resulted in a dose‐dependent effect on reproductive success and skeletal ossification. The effect of mescaline on reproductive success included an increased number of resorptions resulting in a decreased litter size. The 32 mg/kg dose of mescaline caused 48.8% resorptions, while 16 mg/kg and control animals had 12.0% and 6.4% resorptions, respectively. Litter size was decreased from 12.0 pups in controls to 10.3 (16 mg/kg) and 6.5 (32 mg/kg) pups per litter in treated groups. No gross abnormalities were observed at necropsy; there was, however, a dose‐dependent increased delay in the ossification of the skull, sternum, and metatarsals. Both epinephrine and norepinephrine caused a decrease in reproductive success when administered at 500 μg/kg. Epinephrine appeared to cause a trend towards preimplantation wastage as indicated by an increased corpora lutea to implantation site ratio (from 1.3–1.9). Norepinephrine, however, caused an increased number of resorptions (29.1% in controls). Both norepinephrine and epinephrine produced similar delays in ossification.
Correlation between the molecular structure of N‐alkylureas and N‐alkylthioureas and their teratogenic properties
Authors: Teramoto S. , Kaneda M. , Aoyama H. , Shirasu Y.
Published: June 2005

Eleven urea compounds were administered individually as a single oral dose to rats either on day 12 or 14 and to mice on day 10 of pregnancy. 1‐Methylurea and 1‐ethylurea were not teratogenic in either of the animal species. Administration of 1‐methylthiourea and 1‐ethylthiourea, however, resulted in high incidences of malformations in the rat but not in the mouse fetuses. The types of malformation were similar to those produced by the known teratogen ethylenethiourea. Methylated ureas such as 1,3‐dimethylurea, 1,3‐dimethylthiourea, 1,1,3,3‐tetramethylurea, and 1,1,3,3‐tetramethylthiourea were fetotoxic and produced malformations in the tail, palate, or extremities of the surviving rat and/or mouse fetuses. These findings suggest that the teratogenic properties of N‐alkylureas can be categorized into two groups, i.e., mono‐alkylated thioureas and methylated ureas or thioureas.
Correlation between alterations in Meckel's cartilage and induction of cleft palate with β‐aminoproprionitrile in the rat
Authors: Diewert Virginia M.
Published: June 2005

The lathyrogen β‐aminoproprionitrile (BAPN) induces cleft palate in rats when administered at a critical time in secondary palate formation. BAPN is known to inhibit the crosslinking of newly synthesized collagen, but its primary site of action in producing cleft palate is unknown. In this study timemated Sprague‐Dawley rats were given a single oral dose of 600 mg/kg BAPN at five known gestational ages in the 48 hours before palatal shelf elevation, and the fetuses were studied on days 16, 17 and 18. Evaluation of craniofacial relations and palate development in BAPN‐treated heads revealed that delayed palatal shelf elevation and resulting cleft palate were related to retrognathia of the mandible. However, shortening of the mandible was due primarily to vertical and lateral bending of Meckel's cartilage. High and retruded tongue positions that were present with the deformities in Meckel's cartilage interfered with palatal shelf movement to the horizontal plane. The group treated with BAPN at 15 days 7 hours, approximately 24 hours before normal palatal shelf elevation, had the most severe defects in Meckel's cartilage, the longest delay in palatal shelf elevation and the highest incidence of cleft palate. Inhibition of crosslinking of collagen in Meckel's cartilage appeared to weaken the cartilage during the critical period in facial development when extention of the tongue and mandible beneath the primary palate is required to facilitate palatal shelf elevation.
Cortisone‐induced cleft palate in A/J mice: Failure of palatal shelf contact
Authors: Diewert Virginia M. , Pratt Robert M.
Published: June 2005

Although cortisone treatment for induction of cleft palate in mice has been shown to delay the time of palatal shelf elevation, the effects of delayed elevation of shelf contact have not been critically evaluated in a cortisone‐sensitive mouse strain. The objective of this study was to evaluate palatal development in cortisone‐treated A/J mice in order to determine whether the shelves make contact upon elevation. Morphometric analysis of frozen sections revealed that cortisone‐treated shelves were smaller than control shelves with apparent reductions in both the content of extracellular matrix and the number of cells. At a light microscopic level, thinning of medial epithelium in cortisone‐treated palates appeared similar to that in untreated palates with spontaneous cleft lip and palate. Shelf elevation was delayed by approximately 12 hours and only half of the cortisone‐treated palates achieved complete horizontal positioning of the shelves in all regions of the palate. Immediately after elevation, all control palates had extensive vertical contact along the complete length of the palate. In contrast, approximately 20% of the cortisone‐treated fetuses had contact between the shelves in the middle palate region only, with the mean area of contact only 20% as large as in control fetuses. As a result, the net shelf contact in all the cortisone‐treated fetuses was only 4% of the potential contact shown in control fetuses. Therefore, failure of the palatal shelves to elevate and make extensive contact appeared to be the major factor contributing to cortisone‐induced cleft palate in A/J mice.
The effects of phenytoin on rat development: An animal model system for fetal hydantoin syndrome
Authors: Lorente Carol A. , Tassinari Melissa Sherman , Keith David A.
Published: June 2005

An animal model system has been established which reproduces some of the features of the Fetal Hydantoin Syndrome. This pattern of altered growth and development includes growth retardation, craniofacial anomalies, distal phalangeal hypoplasia, and mental deficiency. Rats exposed in utero to phenytoin on gestational days 9, 11, and 13 exhibited fetal onset growth retardation, abnormalities of the craniofacial region and axial skeleton. In addition, the exposed offspring had significantly lower fetal weights, a shortened snout and a high‐arched, irregular palate, and significant delays in skeletal maturation. These abnormalities resemble those reported for the Fetal Hydantoin Syndrome and provide a means to study the effect of phenytoin on the morphological and biochemical development of the fetus.
Lack of teratogenic effects of air at high ambient pressure in rats
Authors: Bolton Margie E. , Alamo Arturo L.
Published: June 2005

The purpose of the research was to determine if pregnant rats subjected to a maximum tolerated duration of exposure to air at 6 atmospheres absolute pressure (ATA) (50.3 meters seawater) would have an increased frequency of fetal death, resorption, low birth‐weight, or malformations. Ninety pregnant rats were assigned to one of three exposure schedules during organogenesis: days 9–11, 12–14, or 15–17, and were randomized between one treatment and two control groups. The treatment group was subjected to 6 ATA for 70 minutes with compression and decompression at 1.8 ATA (18.3 meters seawater)/minute. Control groups were exposed to either 1 ATA of air (surface) within the hyperbaric chamber, or 1 ATA of air outside the chamber. For 30 minutes following decompression, chamber‐treated animals were placed in a slow, motor‐driven rotating cage, and assessed for gait disturbances from decompression sickness. On Day 20 of gestation, laparotomy was performed, and corpora lutea, implantations, and resorptions were counted. Fetuses were weighed, sexed, and examined for gross malformations. Subsequently, they were fixed, sectioned, and examined for visceral anomalies. Minor visceral anomalies and anatomical variations were present in 16.3% of all fetuses; however, no significant differences existed between groups. Similarly there were no significant differences when number of resorptions, number of dead fetuses, mean fetal weights, and malformations were compared by analysis of variance. Finally, there was no relation between symptoms of decompression sickness and any of the above measures. These results indicate that exposing rats to air at increased atmospheric pressure does not affect fetal health or survival.
Embryotoxicity of 9‐(s)‐(2,3‐dihydroxypropyl)adenine
Authors: Jelínek R. , Holý A. , Votruba I.
Published: June 2005

Embryotoxic properties of a novel nucleoside analog, 9–(S)‐(2,3‐dihydroxypropyl)adenine (DHPA), with powerful antiviral activity were estimated using the Chick Embryotoxicity Screening Test (CHEST). Exerting no substantial influence upon function of the caudal morphogenetic system on Day 1.5 (stages HH 10–11), the substance manifested strong embryotoxic action when administered in 30‐ and 100‐μg doses on Days 2 or 3. Deviant morphogenesis involved brain vesicles, eyes, the face, body wall, extremities, the heart, and great vessels. The malformations often combined into the characteristic triad comprising microphthalmia, cleft beak, and reduction deformities of the limbs. Embryo‐toxic properties of an enantiomer (R)‐DHPA were less frequently expressed, when compared with those of (S)‐DHPA, parallelling their known antiviral activity. The effects of DHPA can be substantially reduced by simultaneous administration of adenine nucleosides. The distribution analysis of (S)‐DHPA after application on Day 3 revealed most of the drug unchanged in the yolk and the embryo proper indicating that for expression of the embryotoxic properties no metabolic activation of DHPA was needed. As the embryotoxicity of DHPA was confirmed, even in mice, the biological effect of the drug seems to be of a general character.
Progestins during pregnancy and hypospadias
Authors: Mau Guenter
Published: June 2005

In a sample of 3,602 male newborns we found 33 patients with hypospadias; eight of them were exposed to progestins during early pregnancy. The relative risk for hypospadias after exposure was 1.75 (confidence intervals 0.5–4.4). Progestin intake during early pregnancy does not measurably contribute to the incidence of hypospadias in the population studied.
Effects of 2.45 GHz CW microwave radiation on embryofetal development in mice
Authors: Nawrot P. S. , McRee D. I. , Staples R. E.
Published: June 2005

The embryofetal toxicity and teratogenicity of plane‐wave 2.45 GHz continuous wave (CW) microwave radiation at different intensities were investigated in the CD‐1 mouse. Mice were exposed on days 1–15 of gestation to an incident power density of 5 mW/cm2 (specific absorption rate of 6.7 mW/gm) and either on days 1–6 or 6–15 of gestation to 21 mW/cm2 (specific absorption rate of 28.14 mW/gm) or to 30 mW/cm2 (specific absorption rate of 40.2 mW/gm) for 8 hours daily. Exposure either on days 1–6 or 6–15 of gestation to a power density of 21 or 30 mW/cm2 caused an increase in colonic temperature of exposed dams of 1°C and 2.3°C, respectively. To distinguish between “thermal” and “nonthermal” effects of 21 or 30 mW/cm2, groups of mice were also exposed to elevated ambient temperature to raise their body temperature to the level of those animals exposed to microwave. Ambient temperatures of 30°C and 31 °C increased the deep colonic temperature to that obtained with the 21 and 30 mW/cm2 microwave exposure, respectively. The temperature‐exposed mice were handled in exactly the same manner as the microwave‐exposed mice. A significant reduction in maternal weight gain, either during treatment on days 1–6 or 6–15 of gestation was observed in females of all handled groups. Handling plus exposure to elevated ambient temperature (30°C or 31 °C) during days 6–15 of gestation increased this reduction in maternal weight gain. A significant decrease in implantation sites per litter and reduction in fetal weight was noted in the group exposed to 30 mW/cm2 during days 1–6 of gestation. Exposure of mice to a power density of 30 mW/cm2 (days 6–15 of gestation) resulted in a slight, but significant increase in the percentage of malformed fetuses, predominantly with cleft palate, when compared to all other groups.
Oocyte aneuploidy screening using superovulating prepubertal mice: Effect of methotrexate
Authors: Gates Allen H. , Donaldson Catherine H. , Levy Melissa D.
Published: June 2005

Numerical chromosomal aberrations (aneuploidy) are a major factor in pregnancy wastage, birth defects, and mental retardation. Consequently, effective cytogenetic procedures in mammalian gamates are required for studying mechanisms and causes of chromosomal nondisjunction. Our aims were to determine for oocytes from superovulating prepubertal mice: (1) the yield of chromosomally scorable ova, following application of a double fixation procedure; (2) the background level of aneuploidy, and (3) the sensitivity to induction of aneuploidy (by methotrexate). Superovulation was induced in C129F1 hybrid mice, 22–24 days old, with pregnant mare serum and human chorionic gonadotropin (HCG). Diurnal photoperiodicity and injections were scheduled to assure HCG‐induced ovulation of known timing. Methotrexate (200 mg/kg) was given at 3 hr and ova were recovered at 15 hr after HCG. We describe the adaptation of a double fixation procedure to mouse oocytes. Methotrexate led to significantly increased hypoploidy (2 1/2‐fold) but not to the hyperploidy reported by others for adult mice. There was a high yield of ova with exactly countable chromosomes (average of 9.5 ova per mouse). Concomitantly, the background level of aneuploidy was very low (0/465 scorable ova were hyperploid). Given the additional advantages of economy and convenience, the superovulating 3‐week‐old mouse could be an effective source of ova for testing environmental agents for their aneuploidy‐inducing potential; however, further studies are needed to establish the degree to which such ova are susceptible to aneuploidy induction.
The classification and development of cadmium‐induced limb defects in mice
Authors: Messerle Karin , Webster William S.
Published: June 2005

The aim of this study was to investigate the teratogenic action of cadmium (Cd) on the developing mouse limb. Pregnant mice (C57BL/6J strain) received an injection of 4mg/kg CdCl2 on day 8,9 or 10 of gestation. These animals and saline injected controls were sacrificed either on the day before birth or at various times up to 72 hours after injection.

Limb defects occurred after treatment on each day, the most severe occurring after early treatment. The forelimb deformities were predominantly postaxial reduction while hindlimb defects were preaxial and involved reduction, hypertrophy, syndactyly and polydactyly. The most severe limb reductions were associated with abnormalities of the spinal cord.

Eight to 12 hours after maternal injection with Cd on day 9, the cells of the neural tube and forelimb buds from affected embryos showed large numbers of cytolysosomes. In severely affected limbs both ectodermal and mesodermal cells were involved. In less affected limbs the cytolysosomes were restricted to the mesodermal cells immediately deep to the ectoderm. Right and left limbs appeared to be equally involved with damage extending throughout the craniocaudal length of the limb. By 24 hours most of the cytolysosomes had disappeared. In the neural tube they were replaced by large amounts of cell debris while in the limbs a range of morphology was seen. In the least developed limbs there were still some inclusions but also extracellular debris, while in other, more developed limbs, there was little or no sign of damage. By 48 and 72 hours after treatment all signs of cellular damage had disappeared. The wall of the neural tube however, was frequently thin and sometimes discontinuous while the limbs showed abnormalities in shape such as flattening of the postaxial margin and shortening of the anterior‐posterior axis.
Comparisons of Eccrine sweat gland anatomy in genetic, chromosomal, and other diseases, and a suggested procedure for use of sweat gland measurements in differential diagnosis
Authors: Shankle William R. , Azen Stanley P. , Landing Benjamin H.
Published: June 2005

Statistical analysis of the dimensions of microdissected eccrine sweat glands (duct length, coil volume, ratio of coil volume to duct length, and axis ratio of coil) was performed for several diseases (cystic fibrosis of the pancreas, Werdnig‐Hoffmann disease, tetralogy of Fallot, chronic renal disease, and trisomies 13, 18, and 21) using both individual and grouped age‐matched control patients. Duct length, coil volume, and the ratio of the two all rise with age. Eccrine gland duct length was found to be significantly large in tetralogy of Fallot and Werdnig‐Hoffmann disease and small in chronic renal disease (less so in males than in females, trisomy 13 and trisomy 18). Secretory coil volume was significantly smaller than normal in trisomy 21 (Down syndrome) and in chronic renal disease, and the ratio of coil volume to duct length was low in trisomy 21 and chronic renal disease. The shape of the secretory coil (axis ratio) was possibly abnormal in trisomy 13. Gland dimensions were normal for cystic fibrosis.

Using the multivariate procedure of discriminant analysis, it was found that sweat gland measures significantly contributed to the differentiation of diseases, after adjustments were made for variations in age‐at‐death. This suggested the possibility that criteria for distinction of clinically similar genetic, metabolic, or chromosomal diseases by study of the anatomic properties of eccrine glands obtained by skin biopsy could be developed.

A procedure of analysis comparing the “percentage of normal” of gland dimensions for each disease to control values, and thereby differentiating disease categories on the basis of the “percentage of normal” values, is presented.
The in vitro teratogenicity of cyclophosphamide in rat embryos
Authors: Greenaway J. C. , Fantel A. G. , Shepard T. H. , Juchau M. R.
Published: June 2005

When Day 10 rat embryos were grown in culture containing cyclophosphamide, an hepatic microsomal fraction (S‐9), and cofactors for monooxygenation, they developed characteristic malformations. When a fixed volume of CP was added to cultures the number of malformed embryos was increased and their growth decreased dependent upon the S‐9 concentration. In one group of experiments S‐9 was prepared from animals which had been pretreated with either phenobarbital (PB) or 3‐methylcholanthrene (MCA). All embryos cultured with CP by S‐9 from animals pretreated with polychlorinated biphenyls (Aroclor 1254) (μl/ml) was used. No malformations were seen under the same conditions when MCA‐induced S‐9 (0.25–12.5 μl/ml) was substituted. The teratogenic activation of CP by S‐9 from animals pretreated with polychlorinated byphenyls (Aroclor 1254) was inhibited in vitro by the addition of either metyrapone or carbon monoxide. Embryos which were exposed to CP (25 mg/kg) in vivo on Day 10 were indistinguishable from embryos treated in vitro. All developed characteristic defects and had significant decreases in growth parameters when compared to control litters receiving only vehicle. No histological differences were seen between embryos treated in vivo or in vitro. These data provide further evidence that the teratogenicity of CP is dependent upon one or more maternal P450 monooxygenase systems.
Reproduction and fetal development in mice chronically exposed to nitrous oxide
Authors: Mazze Richard I. , Wilson Anne I. , Rice Susan A. , Baden Jeffrey M.
Published: June 2005

The effects of exposure to nitrous oxide on reproductive indices, fetal development, and male fertility were examined in Swiss/ICR mice. In experiment I, female mice were exposed for 4 hours per day on days 6–15 of pregnancy, to 0.5% (5,000 ppm), 5.0% (50,000 ppm), or 50% (500,000 ppm) nitrous oxide. Control mice were untreated, exposed to compressed air, or treated with retinoic acid on day 8 of gestation. In experiment II, male mice were treated, as above, for 9 weeks and then mated nightly for 7 nights to untreated, virgin females. In experiment I, 1,761 fetuses from 154 dams were examined and found to be without evidence of adverse nitrous oxide treatment effects. In experiment II there were no differences among the groups in the ability of males to impregnate females or in litter size, fetal wastage, or fetal size. When we compare nitrous oxide with other inhalation anesthetics we have studied employing a similar protocol, we find the order of reproductive toxicity to be: halothane > enflurane > methoxyflurane > nitrous oxide. None of the agents were toxic, however, at the trace concentrations usually found in operating rooms.
Parasitic conjoined twins, two cases, and their relation to limb morphogenesis
Authors: Stephens Trent D. , Siebert Joseph R. , Graham John M. , Beckwith J. Bruce
Published: June 2005

Reports of parasitic conjoined twins have appeared rarely in the scientific literature and only one study has included a detailed description of the parasitic extremities. We report here two specimens consisting for the most part of normal hosts with ectopic legs attached to the thorax (case 1, thoracoparasitus) or the abdomen (case 2, gastroparasitus). These two specimens are in agreement with several others reported in the literature in having no sign of vertebral columns. These specimens also exhibit a marked decrease in innervation (case 1) or complete absence of somatic nerves (case 2). This finding is in complete contradiction with the idea of the dependence of limb skeletal structure upon peripheral nerves. The hypothesis is presented that this type of parasitic twin may result from duplication of the Wolffian ridge.
An anatomical study of three cases of alobar holoprosencephaly
Authors: Mieden Gregory D.
Published: June 2005

One case of median cleft lip with hypotelorism and two cases of cyclopia, all with brains exhibiting alobar holoprosencephaly, were examined by detailed anatomical dissection. The results indicate that the variations of the skull and associated soft structures form a continuum, as do the brain, eye, and face, from the mild to severe end of the syndrome. At the mild end, the bony malformations were primarily limited to the structures derived from the frontonasal prominence, within which the ethmoid bone was the focal point. Malformed soft structures included the muscles of the anterior and posterior neck regions. At the severe end of the spectrum, these structures were more severely malformed, and the sphere of malformations widened to include more peripherally located bones and soft structures such as the mandible, ear ossicles, muscles of mastication, and salivary glands. Possible mechanisms for the generation of the malformations are addressed.
Perinatal death and respiratory apparatus dysgenesis due to a bis (dichloracetyl) diamine
Authors: Kilburn Kaye H. , Hess Rex A. , Lesser Marvin , Oster Gerald
Published: June 2005

N, N1‐bis (dichloracetyl) diamine 1, 8‐octomethylenediamine (WIN 18,446) is an experimental drug which was first investigated as a male contraceptive. It is soluble in lipid solvents but not in water. The administration of 1,200 to 1,600 mg/kg to pregnant rats on the tenth day of gestation produced multiorgan fetal malformations. Smaller doses, 400 to 800 mg/kg, especially if divided over 2 or 3 days, caused perinatal death. Thus, 60 to 100% of offspring of rats given WIN 18,446 on the tenth and 11th days of gestation died at birth or within 4 days (Taleporos et al., 78). The present study investigated such deaths. At doses of 200 mg/kg on day 10 or 50 mg/kg on days 10 and 11,67% of offspring had defective or absent diaphragms, 48% had tracheobronchiomegaly with cystic lungs, and 67% had pleural hemorrhage. At doses of 100 mg/kg given on 1 day or 25 mg/kg each day for 2 days, 50% had tracheobronchiomegaly with cystic lungs and rudimentary acini. At lower doses (18.8 mg/kg × 2 or 12.4 mg/kg × 3), a majority of fetal lungs had rudimentary acini, thick septa, few capillaries, and wide cuffs of perivascular connective tissue. Thus, a chemical given during organogenesis produced dysgenesis of the respiratory apparatus. Varying the dose produced malformed lungs with persistently deficient acini which model such human lung faults as tracheobronchiomegaly (Mournier‐Kuhn Syndrome; Mounier‐Kuhn, '32), bronchiolar dysplasia (Wilson‐Mikity Syndrome), and perinatal death with acinar failure resembling neonatal hyaline membrane disease.
Sodium salicylate teratogenicity in vitro
Authors: Greenaway J. C. , Shepard Thomas H. , Fantel Alan G. , Juchau Mont R.
Published: June 2005

Rat embryos were exposed to sodium salicylate in vitro at concentrations comparable to those used to produce terata in vivo. Embryos treated with 400, 600, or 800 μg Na salicylate/ml were compared with embryos treated with an equimolar concentration of NaCl. When compared to growth of the controls, a significant dose‐dependent decrease in growth parameters was observed. The incidence of abnormal embryos characterized by generalized swelling (particularly in the area of the rhombencephalon) was also dose dependent. This study demonstrates the teratogenicity of salicylate in the rat independent of maternal factors.
Do organophosphate insecticides inhibit the conversion of tryptophan to NAD+ in ovo?
Authors: Henderson Melodie , Kitos Paul A.
Published: June 2005

The hypothesis that organophosphate (OP) insecticides reduce the NAD+ levels of chick embryos by inhibiting kynurenine formamidase was tested. Fertile chicken eggs at 3 days of incubation were treated with a teratogenic dose of the organophosphate insecticide diazinon (DZN) in the presence or absence of exogenous L‐tryptophan or nicotinamide, or one of the metabolic intermediates (L‐kynurenine, 3‐hydroxyanthranilic acid, quinolinic acid) between tryptophan and NAD+. By day 10 of development, DZN reduced the NAD+ content of the hind limbs of the embryos to less than 20% of normal and by day 15 it caused severe type I and type II teratogenic responses. The co‐presence of tryptophan or one of its metabolites served to maintain the NAD+ levels of DZN‐treated embryos close to or above normal and significantly alleviated the symptoms of type I teratisms. Tryptophan is virtually as effective as most of its metabolites in suppressing the effects of DZN on the NAD+ content and physical development of the embryos. This equivalence does not support the proposition that the inhibition of kynurenine formamidase causes the lowered NAD+ levels involved in OP‐induced type I teratogenesis. It is consistent with the concept that the insecticide acts to decrease the availability of tryptophan to the embryo.
Congenital cystic microphthalmia and consequent anophthalmia in the rat: A study in abnormal ocular morphogenesis
Authors: Kinney Hannah C. , Klintworth Gordon K. , Lesiewicz Jeanne , Goldsmith Lowell A. , Wilkening Beth
Published: June 2005

An otherwise normal adult Charles River rat (CD strain) was observed to have no recognizable eyes. Breeding and morphological studies were undertaken to determine the nature of the ocular defect, as well as its cause and pathogenesis. The anomaly was found to be inherited as an autosomal recessive trait with variable expressivity. It was characterized by unilateral or bilateral congenital microphthalmia with multiple associated ocular abnormalities including a neuroepithelial cyst, optic nerve aplasia, and cataract. In several elderly rats, no eye was found histologically in the orbit, suggesting reabsorption of malformed tissues as the basis of the anophthalmia. Study of the prenatal morphogenesis of the microphthalmia suggested that the primary disorder reflects a disturbance of the neuroepithelium of the retinal anlage and results in defective early formation of the optic cup. The abnormalities in other ocular structures, particularly in the lens, are considered secondary. This ocular malformation emphasizes the early interactions and interdependence of the lens and retina in normal morphogenesis and provides an animal model for study of lens‐retinal relationships in abnormal morphogenesis. It is particularly relevant in understanding the pathogenesis of microphthalmia with cysts in the human eye.
Vitamin B6 reduces cortisone‐induced cleft palate in the mouse
Authors: Yoneda Toshiyuki , Pratt Robert M.
Published: June 2005

Administration of Vitamin B6 during gestation to mice on a Vitamin B6‐containing diet resulted in a substantial reduction in cortisone‐induced cleft palate. Mice maintained on a Vitamin B6‐deficient diet demonstrated an increase in the frequency of cortisone‐induced cleft palate; this effect was prevented by administration of Vitamin B6. Vitamin B6 inhibited the specific binding of a labeled glucocorticoid to cytosolic receptors from cultured palatal mesenchyme cells. These results indicate that Vitamin B6 reduces the incidence of cortisone‐induced cleft palate by altering the binding of glucocorticoids to their cytoplasmic receptors and subsequently nuclear acceptors.
Teratogenic effects of valproic acid and diphenylhydantoin on mouse embryos in culture
Authors: Bruckner A. , Lee Y. J. , O'Shea K. S. , Henneberry R. C.
Published: June 2005

Teratogenic effects of the anticonvulsant drugs valproic acid (VPA) and diphenylhydantion (DPH) on the development of mouse embryos during early organogenesis were studied using the whole embryo culture technique. Embryos with one to seven somites were exposed in vitro to 50–375 μg/ml VPA or 15–135 μg/ml DPH for up to 42 hours and compared to control embryos cultured in 80% rat serum without either drug. For both VPA‐ and DPH‐treated embryos, a dose‐dependent increase in the frequency of abnormal embryos and a decrease in viability were found. VPA and DPH produced a similar pattern of defects. Drug‐induced anomalies included open neural tubes in the cranial regions, abnormal body curvature, craniofacial deformities, and yolk sac defects. Ultrastructural changes were noted in the neuroepithelium of exencephalic VPA‐treated embryos. Growth and development were retarded in embryos exposed to > 35 μg/ml DPH or > 50 μg/ml VPA as indicated by the decrease in protein and DNA content and the reduction in somite number, crown‐rump length, and yolk sac diameter. On a molar basis DPH was potentially more teratogenic than VPA, which correlates with the higher lipid solubility of DPH. With VPA, susceptibility to the drug depended on the developmental stage; e.g., at 150 μg/ml VPA the frequency of malformations was 70% in embryos with one to four somites as compared to 35% in embryos with five to seven somites.
Developmental and cytogenetic effects of potassium dichromate on mouse embryos in vitro
Authors: Iijima Sumio , Spindle Akiko , Pedersen Roger A.
Published: June 2005

Mouse blastocysts and egg cylinders were treated in vitro with potassium dichromate (K2Cr2O7, 5 × 10−7 to 2 × 10−6 M), and the effects on postimplantation development and induction of sister chromatid exchanges (SCEs) were determined. When blastocysts were treated for six days with 1 × 10−6 M K2Cr2O7, the number of embryos with growing inner cell masses (ICMs) and ICMs that were differentiated into primary endoderm and ectoderm were significantly reduced. The number of embryos forming trophoblast outgrowths was not reduced, but outgrowth formed in the presence of 2 × 10−6 M K2Cr2O7 were small and began to degenerate by the end of the treatment. Hatching and attachment were not affected at any concentration. The frequency of SCEs was significantly increased at ≥ 1 × 10−6 M. When egg cyclinders were treated with K2Cr2O7 for 24 hours, the number of embryos with blood islands, fusion of the allantois with the chorion, and beating heart was significantly reduced at all concentrations tested, and the crown‐rump lengths of embryos were significantly reduced at 1 to 2 × 10−6 M. The frequency of SCEs was increased in embryonic tissues of egg cylinders cultured in ≥ 1 × 10−6 M K2Cr2O7. Increased SCE frequencies were observed at lower concentrations in extraembryonic tissues, which had higher SCE frequencies than embryonic tissues at all concentrations tested. The correlation between developmental effects and SCE frequency suggests that cytogenetic damage may be largely responsible for the detrimental effects of dichromate on mouse embryos.
Decrease of learning capacity in offspring with increasing paternal age in the rat
Authors: Auroux Maurice
Published: June 2005

The same 15 male Wistar rats at the ages of 2.5, 6, 10, 14, 18, and 22 months were successively randomly mated with 2.5‐month‐old females. In a separate experiment, 15 male Wistar rats at the age of 2.5 months and 15 at the age of 23 months were simultaneously randomly mated with 2.5‐month‐old females. Offspring were evaluated in regard to the mean number per litter, sex ratio, frequency of gross external malformations, growth pattern, and mortality in the first 13 weeks of life and reproductive capacity at 13 weeks of age. They were also evaluated for spontaneous activity and emotionality with an open field test and for learning capacity with an avoidance conditioning test, both carried out between 10 and 13 weeks of age. Only learning capacity of the offspring, expressed in percentage of success for male or female, decreased consistently and significantly as the father's age increased. But females did not seem to be affected in the same way as males. The genetic implications are briefly discussed.
Behavioral outcome after prenatal exposure to phenytoin in rats
Authors: Mullenix Phyllis , Tassinari Melissa Sherman , Keith David A.
Published: June 2005

The long‐term behavioral outcome subsequent to prenatal exposure to phenytoin was examined in an animal model for the Fetal Hydantoin Syndrome. Behavioral outcome was determined by two different techniques—the residential maze, which provided a 24‐hour measure of horizontal movement frequency in a group of animals, and time‐lapse photography, which allowed quantification of frequency, duration, distribution, and sequencing of 15 motor acts performed by individual rats. Phenytoin induced significant, sex‐related changes in motor behavior. Ten‐week‐old females exposed in utero to phenytoin displayed hypoactivity comprised of a longer duration, greater frequency, and more random distribution of grooming behaviors. Prenatally exposed males at that age displayed an opposite effect of hyperactivity consisting of a longer duration and greater frequency of exploratory behaviors. It appears that prenatal exposure to phenytoin may affect normal maturational changes in motor behavior so that immature activity levels are maintained in the adult animal.
Structural teratogenicity evaluation of methyl chloride in rats and mice after inhalation exposure
Authors: Wolkowski‐Tyl R. , Phelps M. , Davis J. K.
Published: June 2005

One hundred bred Fischer‐344 female rats were exposed daily for 6 hours to atmospheres containing 0, 100, 500, or 1,500 ppm methyl chloride, 25 females per exposure concentration, from gestation day (gd) 7 through gd 19. On gd 20, the females were sacrificed for evaluation of maternal reproductive and fetal parameters. Maternal and fetal toxicity was apparent at the highest exposure concentration. There were no methyl chloride‐induced external, skeletal, or visceral abnormalities seen in the fetuses. One hundred thirty‐two C57BL/6 female mice bred to C3H males to produce B6C3F1 offspring were exposed daily for 6 hours to atmospheres containing 0, 100, 500, or 1,500 ppm methyl chloride, 33 females per exposure concentration, from gd 6 through gd 17. Exposure to the entire 1,500‐ppm group was terminated on gd 10–14, with the animals killed in extremis. Selective necrosis of neurons in the internal granular layer of the cerebellum, ranging from individual cell involvement to focal areas comprising large numbers of neurons, was found in all females. On gd 18, the females from the other treatment groups, all of which survived, were killed for evaluation of maternal reproductive and fetal parameters. No evidence was seen of maternal or fetal toxicity in these exposure groups. There were no significant alterations in external appearance in fetuses from any of the exposure groups. Visceral examination of mouse fetuses revealed a small, but statistically significant, incidence of heart defects in litters of the 500‐ppm group. The anomaly, a reduction or absence of the atrioventricular valve, chordae tendineae, and papillary muscle, was observed on the left side (bicuspid valve) in three fetuses and the right side (tricuspid valve) in six fetuses: three males and six females. It is concluded that methyl chloride inhalation exposure in pregnant rats, during critical periods of embryo and fetal development, is not teratogenic at concentrations which elicit maternal and fetal toxicity. In pregnant mice, methyl chloride was severely toxic to dams following 4 days or more of exposure to 1,500 ppm in air. Methyl chloride, at 500, but not 100 ppm, was teratogenic in mice, leading to a malformation in the heart. No embryo‐fetal toxicity or teratogenicity was associated with exposure of mice, during critical periods of embryo and fetal development, to 100 ppm of methyl chloride.
Evaluation of heart malformations in B6C3F1 mouse fetuses induced by in utero exposure to methyl chloride
Authors: Wolkowski‐Tyl R. , Lawton A. D. , Phelps M. , Hamm T. E.
Published: June 2005

C57BL/6 female mice impregnated by C3H male mice to produce B6C3F1 fetuses were exposed daily for six hr to atmospheres containing 0, 250, 500, or 750 ppm methyl chloride, from gestation day 6 to gestation day 18. There were 74 to 77 females with copulation plugs per exposure concentration. Females exposed to 750 ppm methyl chloride exhibited ataxia commencing on the seventh day of expsure (gestation day 12). They also showed hypersensitivity to touch or sound, tremors and convulsions. Six females in the 750 ppm group died and one was euthanized in extremis prior to scheduled sacrifice. On gestation day 18, all other females were euthanized for evaluation. Only dams exposed to 750 ppm exhibited significant decrease in body weight by gestation day 18, weight gain during the gestation period, and absolute weight gain (weight gain minus gravid uterine weight) versus controls. There were no treatment related‐effects on these parameters in the other exposure groups. None of the groups exhibited exposure‐related differences in pregnancy rate, gravid uterine weight, or maternal liver weight. There were no differences in the numbers of implantations, resorptions, dead fetuses, nonlive (dead plus resorbed) fetuses, live fetuses, sex‐ratio, or mean fetal body weight per litter. There was a significant exposure‐related increase in the number and percentage of affected (nonlive plus malformed) fetuses per litter with the incidence of affected fetuses in the 750 ppm group significantly higher than controls. There was a statistically significant increase in the incidence of heart defects in the 500 and 750 ppm group relative to controls. Of the 37 fetuses in the study with heart defects, 23 were females, 14 were males. The heart defects observed included: absent or abnormal tricuspid valve, reduced number of papillary muscles and/or chordae tendineae on the right side, small right ventricle, globular heart, and white spots in the left ventricular wall. Multiple malformations were observed in one fetus from the 500 ppm group and in three fetuses in the 750 ppm group. It is concluded that methyl chloride inhalation exposure to pregnant C57BL/6 mice from gestation day 6 through gestation day 17 resulted in maternal toxicity only at the 750 ppm exposure concentration and was teratogenic to B6C3F1 conceptuses at exposure concentrations of 750 and 500 ppm, leading to fetal heart malformations. No evidence of embryo or fetotoxicity other than teratogenicity was seen at any of the exposure concentrations employed. No maternal, embryo or fetotoxicity or teratogenicity was associated with exposure of mice, during critical periods of embryo and fetal development, to 250 ppm of methyl chloride.
Induction of feather malformations in chick embryos by cadmium: Protection by zinc
Authors: Narbaitz Roberto , Riedel Karen D. , Kacew Sam
Published: June 2005

Various doses of cadmium chloride were injected to chick embryos between the seventh and 14th day of incubation. Doses over 15 μg/egg produced high mortality and, when injected between the tenth and 11th day, widespread curling of the feathers in the surviving embryos. A different type of malformation, consisting of hemorrhagic atrophy of the distal part of the feathers, was observed in the embryos injected with similar doses during the 12th day. No feather malformations were observed in embryos injected before the ninth or after the 12th day of incubation. The simultaneous injection of an equimolar amount of zinc sulfate prevented the feather malformations.
Erythropoiesis in the fetal trisomy 19 mouse. I. Characterization of erythrocyte populations in peripheral blood
Authors: Bersu Edward T. , Crandell Clare , White Beverly J.
Published: June 2005

Changes in the type, size, and relative percentage of different erythrocyte populations in the peripheral blood of individual trisomy 19 and normal littermate mouse fetuses were studied from 12 gestational days to term. Large nucleated erythrocytes of yolk‐sac origin comprise the first population of cells and are gradually diluted out of the circulation by nonnucleated erythrocytes of hepatic origin. This transition occurs between 12 and 16 gestational days. The rate of decline of the nucleated erythrocytes in the trisomic animals lagged by approximately 1 day behind the normal littermates, so that they did not completely disappear from the peripheral circulation until day 17. A slight decrease in size of the nonnucleated erythrocytes which occurs with increasing gestational age was also delayed by approximately 1 day in the trisomic fetuses. These observations are consistent with an hypothesis that one effect of the murine trisomy 19 genome is to retard by 1 day the growth and development of the affected animal.
Cadmium uptake and distribution in mouse embryos following maternal exposure during the organogenic period: A scintillation and autoradiographic study
Authors: Christley J. , Webster W. S.
Published: June 2005

Pregnant C57BL/6J mice were given a single intraperitoneal injection of either a teratogenic (2,400 μg Cd/kg), an intermediate (40 μg Cd/ kg) or a trace dose (0.66 μg Cd/kg) of cadmium chloride (CdCl2) on day 9 of gestation; each dose contained 109CdCl2 (20 μCi). The mice were euthanized at various times after Cd exposure, and the amount of Cd in the embryos was determined in a gamma counter. For all three doses a low, but similar, percentage of the dose rapidly entered the embryos; levels then decreased during the next 11 hours, only to rise again by 24 hours and continue to rise for the remainder of the pregnancy. When the Cd content was related to embryonic weight the Cd concentration was at its highest level after 1 hour and then decreased rapidly and continued to decrease for the rest of pregnancy.

Autoradioraphic studies showed that the teratogenic dose of Cd entered all tissues of the embryos but was particularly localized in cells of the neural tube, limb buds, and gut. By 12 hours, cell damage was seen in the embryos but the affected cells were not necessarily the heavily labelled cells. In embryos exposed to the nonteratogenic dose the highest Cd accumulation was seen in the embryonic gut and limb bud ectoderm but all tissues showed a low level of labelling.
Normal and abnormal appearances of the 35‐day ferret fetus studied by freehand (razor blade) sections and gross examination
Authors: Gulamhusein Amir P. , Beck Felix
Published: June 2005

This communication reports the sectioning and subsequent examination of 1‐mm freehand razor blade sections of the normal 35‐day ferret fetus; pregnancy in the ferret lasts for 42 days. Skeletal and other abnormalities obtained after maternal treatment with teratogens, such as trypan blue, mustine hydrochloride, and sodium salicylate are included for comparison with the normal.
Occurrence of cleft palate, palatal slit, and fetal death in mice treated with a glucocorticoid: An embryo transfer experiment
Authors: Kusanagi Takao
Published: June 2005

SWV and C57BL/6 (C57BL) mice were treated subcutaneously with triamcinolone acetonide in a single dose of 2.5 mg/kg on day 12 of pregnancy (vaginal plug = day 0), and the palate of their fetuses was examined at term. Cleft palate was seen in some SWV and C57BL fetuses; its frequency was significantly higher in the former. Closer examination revealed palatal slit in some C57BL, but in no SWV fetuses. In addition, fetal mortality was significantly increased in SWV, but not in C57BL, exposed to triamcinolone. These strain differences in cleft palate, palatal slit, and fetal mortality were investigated by embryo transfer. The results showed that, in cleft palate induction, the effects of uterine environment were more important than those of fetal genotype. On the other hand, after transfer, palatal slit still occurred in C57BL but not in SWV fetuses; thus, in palatal slit occurrence, the fetal genotype played a more important role than the uterine environment. Accordingly, it is suggested that the nature of the participation of fetal genotype and uterine environment in palatal slit occurrence is different from that in cleft palate induction. In regard to fetal mortality, embryo transfer procedures influenced it in SWV dams and the effect of triamcinolone could not be detected after embryo transfer.