bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of sodium tolbutamide on the uptake of sodium‐35S‐sulfate and 35S‐methionine in inbred strains of mice
Authors: Robertson Donald W.
Published: June 2005

Prenatal treatment with tolbutamide (sodium) has been shown to cause skeletal malformations in mice. The possibility that this agent interferes with sulfur metabolism in the developing mesenchyme‐cartilage‐bone system was tested.

Pregnant female mice of the C57BL/6J and 129/Sv‐Sl strains were injected with single doses of sodium‐35S‐sulfate (2 μC/g) on day 9, 10, 11, or 12, and C57BL/6J females were given single doses of 35S‐methionine (1 μC/g) at the same times in pregnancy. Experimental animals of both groups then received a teratogenic dose (10 mg) of sodium tolbutamide (Orinase, Upjohn). Twenty‐four hours later (day 10, 11, 12, or 13), the embryos were retrieved and homogenized and aliquots of homogenate were processed for the determination of total embryonic protein and of the level of uptake of isotope. The remaining homogenate was treated with trichloroacetic acid (TCA). The TCA‐precipitable protein content was determined and the level of associated radioactivity ascertained.

Results revealed no statistically significant alteration of total embryonic protein weight or TCA‐protein after exposure to tolbutamide, in either strain. There was a statistically significant reduction in the level of uptake of radiosulfate in the experimental groups of both strains. The level of uptake of 35S‐methionine was similar for both control and experimental groups. These results suggest that tolbutamide does not interfere with the incorporation or utilization of the amino acid. The possibility is proposed that this agent interferes with sulfate metabolism during the formation of the sulfated mucopolysaccharides vital to the formation of skeletal tissue.
Abortive effects and comparative metabolism of chlorcyclizine in various mammalian species
Authors: Steffek A. J. , King C. T. G. , Wilk A. L.
Published: June 2005

A high incidence of abortion was produced in Duroc pigs (Sus scrofa) by maternal treatment during organogenesis with 5.5 mg/kg chlorcyclizine. The same dose of chlorcyclizine or hydroxyzine administered to pregnant rhesus monkeys (Macaca mulatta) also resulted in a high frequency of abortion. Species differences in the rate of chlorcyclizine metabolism were shown to exist. Chlorcyclizine was administered to nonpregnant rats, monkeys, and pigs on consecutive days, at teratogenic or abortive doses, and blood levels of norchlorcyclizine, the demethylated derivative of chlorcyclizine, were used as an indication of the rate of metabolism. A comparison of the three species in the rate of conversion to norchlorcyclizine showed that measurable amounts of norchlorcyclizine were present in rat blood 24 hours after the initial dose whereas this metabolite was undetectable in either pig or monkey blood at a similar time period. A comparision of chlorcyclizine metabolism showed that there was more rapid demethylation in monkeys than in pigs as indicated by the fact that chlorcyclizine became undetectable in the blood of monkeys ten days before it did in that of a pig.
Homologies for congenital heart diseases: Murine models, influenced by dextroamphetamine
Authors: Nora James J. , Sommerville Robert J. , Fraser F. Clarke
Published: June 2005

The spontaneous occurrence and teratogenic production of atrial septal defect in A/J mice and ventricular septal defect in C57BL/6J mice lead to the proposal that these strains may represent animal homologies of these congenital heart diseases in human beings. Such models permit investigation into the mechanisms by which nongenetic factors cause genetically predisposed individuals to reach a particular threshold of developmental abnormality and develop a specific type of cardiac malformation.
Lid gap in newborn mice: A study of its cause and prevention
Authors: Harris Muriel Watney , Fraser F. Clarke
Published: June 2005

“Lid gap,” a congenital defect in the C3H/Ml mouse strain determined by a single autosomal recessive, gene (lgMl) with incomplete penetrance, can be prevented by a single prenatal injection of cortisone (Watney and Miller, '64). In the present study the eyes of normal, lid gap, and cortisone‐treated lid gap embryos were studied histologically at the time of normal eyelid closure (days 14 to 18 of gestation). The earliest consistent difference observed between the normal and lid gap eyes was an adhesion between the corneal epithelium and the epidermis of the lid tip in lid gap embryos on day 15 of gestation. The normally linear orientation of nuclei in the lid tip epidermis was subsequently disrupted. It is suggested that such an adhesion could be the cause of the lid gap defect.
The histology of palatal closure in the rhesus monkey (Macaca mulatta)
Authors: Steffek A. J. , Verrusio A. C. , King C. T. G.
Published: June 2005

A study was made of normal palate embryology in rhesus monkeys. Rotation and initial fusion of the palatal shelves occurred during day 46 of gestation. By day 50 degeneration of both the nasal and midpalatal epithelia along the line of fusion was occurring. The stages of palate development in the rhesus monkey agree very well with those reported for human embryos of approximately the same age.
Normal and abnormal nasolabial morphogenesis in the rat
Authors: Smith Sally C. , Monie Ian W.
Published: June 2005

Nasolabial morphogenesis in Long‐Evans rats was studied both antenatally and postnatally. Microscopically, the facial processes corresponded to areas where mesenchyme had condensed to form growth centers. Teratogens such as methyl salicylate, trypan blue, and 9‐methyl PGA when administered to pregnant rats principally caused underdevelopment of the maxillary processes and failure of mergence of the nasomedial processes in the young so that a variety of clefts resulted. In addition, some experimental embryos showed shallow grooving of the maxillary process, which corresponded with the location of maxillary cleft, and abnormality occasionally seen at a later stage in man and other animals.
Fetal malformations produced in rats by N‐isopropyl‐α‐(2‐methylhydrazino)‐p‐toluamide hydrochloride (procarbazine)
Authors: Chaube Shakuntala , Murphy M. L.
Published: June 2005

Single intraperitoneal injections of N‐isopropyl‐α‐(2‐methylhydrazino)‐p‐toluamide hydrochloride (procarbazine) at doses ranging from 5–550 mg/kg were given to pregnant rats on the fifth to twelfth, fourteenth, and seventeenth days of gestation. Malformations were seen in twenty‐first‐day fetuses exposed to doses that were slightly higher than one‐half (250 mg/kg on 17th day) to one forty‐fifth (12 mg/kg on 12th day) the single dose that was lethal to females (550 mg/kg) when they were treated once on the fifth, sixth, ninth to twelfth, fourteenth, or seventeenth day of gestation. Tail and appendicular defects were observed after treatment on all eight days, injury to the brain only after that on the ninth day, facial clefts on the ninth or tenth day, and cleft palate and shortened jaws on the sixth, ninth, twelfth, fourteenth, and seventeenth days. Malformations were not seen with any of the doses used on the seventh or eighth day of gestation. Attempts to protect the twelfth‐day fetus against the teratogenic effects of 100 mg/kg of procarbazine by administration of various amounts of L‐methionine were only partially successful.
Mortality and skeletal malformations from amniocentesis and oligohydramnios in rats: Cleft palate, clubfoot, microstomia, and adactyly
Authors: DeMyer William , Baird Irene
Published: June 2005

Rat fetuses were subjected to amniocentesis on days 14.5 to 16.5 of gestation, and the mothers were sacrificed on day 21.5 to ascertain the condition of the fetuses.

Amniocentesis of day‐14.5, 15.5, or 16.5 rat fetuses resulted in mortality and malformations whose rates were age‐dependent. Amniocentesis on day 14.5 resulted in nearly 100% mortality, while on day 16.5 the mortality rate was only 26%.

Malformations, like mortality, were more frequent after amniocentesis in younger fetuses. Cleft palate occurred only in day‐15.5 animals, but otherwise the malformations after amniocentesis on days 15.5 and 16.5 were similar in type. Compared to controls the fetuses subjected to amniocentesis were smaller and had peculiar, thickened trunks and necks. They had short, stiff extremities with clubfeet, primitive digits or adactyly, scoliotic tails, microstomia, and short umbilical cords. None of the control fetuses had any of these features.

The mechanism of the malformations is postulated to be oligohydramnios and intrauterine immobility.
Viruses and embryos
Authors: Sever John L. , London William T.
Published: June 2005

A number of viruses are capable of producing intrauterine infection and damage. Both rubella and cytomegalovirus may cause malformations. For rubella the most frequent defects are those involving the heart, eyes, brain, and ears. With cytomegalovirus, children may be microcephalic, small, and mentally retarded. The mechanism of teratogenesis for rubella is apparently related to the direct infection of the virus in certain tissues of the developing fetus. Indirect effects may also be caused by vascular occlusion due to damage of blood vessels. Studies of rubella in experimental animals have not been particularly successful. Isolated reports have suggested that congenital damage can be produced in monkeys and rats. Further studies, however, are necessary.

A number of “model systems” are available for the study of viruses in experimental animals. It is now possible to utilize basic guidelines in consideration of experimental teratogenesis in these systems. These guidelines include: 1. Infection should be produced in the adult and fetus or newborn animal. 2. In most cases the virus used should be low passage, well adapted to the animal, and preferably passaged in the living animal. 3. Several different intervals during gestation should be studied, including the inoculation of newborn young. Several dosages and routes should be tried. 4. Indirect effects on the mother or infant, environmental factors, mating patterns, and genetic background variables should be considered. 5. The effects should be prevented by specific neutralization of the virus.
The differential response of the early mouse embryo to actinomycin D treatment in vitro
Authors: Skalko Richard G. , Morse John M. D.
Published: June 2005

Preimplantation mouse embryos (ICR strain) were removed from the oviducts of pregnant females at 55, 60, and 65 hours after ovulation and cultured in a medium containing inorganic salts, horse serum, and sodium pyruvate. Experimental embryos were exposed to a range of dosages of actinomycin D (10−1–10−5 μg/ml) and were observed at 24 and 48 hours after the initiation of the experiment. The results obtained were independent of embryonic stage but demonstrated a distinct dose‐dependency. Exposure to 10−1 μg/ml was incompatible with further development. Embryos exposed to 10−2 μg/ml formed blastocysts (24 hours) at a rate lower than corresponding controls and all were degenerated at the termination of the experiment (48 hours). Blastocyst formation by embryos exposed to 10−3 μg/ml occurred at a rate that was equal to or exceeded control values, but a significant percentage of these blastocysts were degenerated after 48 hours in vitro. Embryos exposed to the lower dosages (10−4 and 10−5 μg/ml) did not differ from corresponding control embryos with respect to the percentage of blastocysts observed at 24 and 48 hours.

These results suggest that actinomycin D affects two developmental processes: blastocyst formation and blastocyst survival or differentiation. The latter of these is more sensitive to the developmental effects of the agent and is at least circumstantially related to the early appearance of the nucleolus in this organism.
Production of fetal rat malformations by norchlorcyclizine and chlorcyclizine after intrauterine application
Authors: Wilk A. L.
Published: June 2005

A technique was developed for the intrauterine application of teratogens to study fetal rat malformations produced by benzhydrylpiperazine compounds. Millipore filters (0.2 × 0.2 cm) impregnated with 50 μg chlorcyclizine HCl, 50 μg norchlorcyclizine HCl, or HCl alone were inserted through the uterine wall and placed on either the intact amniotic sac (over the fetus) or the placenta. Filters containing norchlorcyclizine implanted on the amniotic sac on day 13 or 14 produced 30% cleft palate, while chlorcyclizine filters produced only 3% cleft palate. Limb anomalies were also seen after norchlorcyclizine‐ or chlorcyclizine‐filter insertion. The optimal time of producing these malformations was day 13 or 14 of gestation. The agents exerted localized teratogenic activity since insertion of norchlorcyclizine filters over the head area of day‐14 fetuses resulted in 42% cleft palate, while those placed over the hindlimb produced only 11% cleft palate but 55% hindlimb malformations. Control HCl filters inserted over the fetus and norchlorcyclizine filters placed on the placenta produced no malformations.
Origins of congenital heart disease: An epidemiologic perspective
Authors: Miller Robert W.
Published: June 2005

As is true for laboratory or clinical research, epidemiology can either generate or test hypotheses about the origins of disease. In so doing with respect to cardiac anomalies, rubella virus was identified as an environmental cause and the role of genetics has been clarified. Microscopically visible chromosomal aberrations have been related to high rates of diverse cardiac defects in Turner's and autosomaltrisomy syndromes. Submicroscopic genetic defects may also produce heart anomalies, as in Marfan's syndrome. The role of inheritance in the production of cardiac malformations in general, however, appears to be small as indicated by studies of twins (only 1 of 6 series revealed an elevated concordance rate in identical pairs) or by studies of the effect of consanguinity. Yet a wide variety of congenital heart disease has been repeatedly found to occur excessively in families. Future research must evaluate whether these occurrences are determined pre‐ or postzygotically. By so doing the origins of sporadic cases may be elicited. The possibilities include submicroscopic chromosomal abnormalities, chemical or microbial agents that interfere with normal embryonic development, and combinations of these factors. Through the use of existing data resources epidemiologic research can help to identify the influence of each. Although computer technology has its value, etiologic insight, which can be tested by the epidemiologic method, seems more likely to come from observations made by physicians at the bedside.
Potentiation of the teratogenic effects of 5‐fluorouracil by natural pyrimidines I. Biological aspects
Authors: Wilson James G. , Jordan Robert L. , Schumacher Herbert
Published: June 2005

The uracil analogue 5‐fluorouracil (5‐FU) administered alone on day 9 of rat gestation was nonteratogenic at a dose of 10 mg/kg but highly teratogenic at 20 mg/kg. Simultaneous administration of the natural pyrimidine bases uracil (U) or thymine (Th) and the lower dose of 5‐FU was highly teratogenic and simultaneous administration of U or Th and the higher dose of 5‐FU was totally embryolethal, i.e., all litters resorbed before term. Uridine and thymidine given with 5‐FU had a similar effect but were less potent. The nucleotide thymidine monophosphate at greater than a molar equivalent dose failed to have this effect. The potentiative effect was reduced after a 1‐hour interval and virtually absent after a 3‐hour interval between injections of the analogue and natural base. When carbon tetrachloride was used to cause generalized damage to liver tissue a striking increase in teratogenic effect occurred, indicating that the intact liver tends to protect the embryo by catabolizing 5‐FU.

Studies with 14C‐labeled 5‐FU showed that a significantly greater amount of 5‐FU reached the embryo when the analogue plus U was administered than when the analogue was given alone. It is assumed that nonspecific pyrimidine‐degrading enzymes in maternal liver were temporarily saturated by the combined concentrations of 5‐FU and U, and hence the effect was tantamount either to increasing the dose of teratogen or decreasing liver function. This supposed action by hepatic enzymes is supported by data presented in the following paper in this journal.
Potentiation of the teratogenic effects of 5‐fluorouracil by natural pyrimidines. II. Biochemical aspects
Authors: Schumacher Herbert J. , Wilson James G. , Jordan Robert L.
Published: June 2005

Thymine (Th), uracil (U), and the antimetabolite 5‐fluorouracil (5‐FU) are metabolized in vitro by rat liver enzyme systems present in the high‐speed supernatant soluble cell fraction. The data presented demonstrate that addition of either U or Th to such preparations or the use of livers from rats pretreated intraperitoneally with U or Th markedly decreases the ability of liver preparations to metabolize 5‐FU. These findings indicate that the decreased elimination from the body of a teratogenic dose of 5‐FU after treatment with an equimolar dose of U is due to the inhibition of metabolism of the antimetabolite in the maternal liver.

The concomitant administration of the natural pyrimidines Th or U with 5‐FU resulted in prolonged high serum levels of the teratogen 5‐FU, which tended to enhance transfer to and uptake by the embryo. Since the embryo was unable to dispose of 5‐FU metabolically, prolonged high levels of 5‐FU would be expected to cause increased teratogenic effects. Studies with labeled 5‐FU revealed that most of the radioactivity found in the embryos was incorporated into RNA, with only about 30% in the TCA ex tract. Concomitant treatment of pregnant rats with 5‐FU and U had greater inhibitory effect on the incorporation of formate into the methyl group of DNA thymine in the embryo than treatment with 5‐FU alone. This treatment inhibited thymidylate synthetase more than an equimolar dose of 5‐FU alone. Neither treatment affected the high kinase activity of the embryo.
In vitro study of rat embryos. I. Effects of decreased oxygen on embryonic heart rate
Authors: Shepard Thomas H. , Tanimura Takashi , Robkin Maurice
Published: June 2005

To study directly the effects of hypoxia on the mammalian embryo, rat embryos at the 14‐, 22‐, and 35‐somite stages were explanted into the in vitro system of New. The initial heart rates in the three groups did not differ. With hypoxia the 22‐ and 35‐somite embryos responded with a prompt heart‐rate drop but no significant effect was found in the 14‐somite embryos. Irreversible sludging of yolksac circulation was associated with death in the older embryos.
Transplacental infection of rats and hamsters induced by oral and parenteral inoculations of H‐1 and rat viruses (RV)
Authors: Kilham Lawrence , Margolis George
Published: June 2005

An aim of the present investigations was to use recently isolated strains of H‐1 and RV, which had been subjected to a minimum of laboratory passages, to induce transplacental infection orally in order to replicate natural infections in rats, the natural hosts, as well as in hamsters, which are subject to “spontaneous” infection with these agents. H‐1 virus had a remarkable ability to penetrate both the gut wall and placental barrier and infect fetuses within 24 hours of oral inoculation of pregnant hamsters, whereas such infections could be induced in rats only by parenteral inoculation. However, rats were susceptible to fetal infection with RV given orally. The pathogenesis of infection was somewhat different with the two viruses. RV, in contradistinction to H‐1, proliferated in maternal organs and possibly in the placenta for several days before invading the fetus. Both H‐1 and RV were alike in being transported in the blood in close association with erythrocytes. All fetuses invaded by either agent developed widespread infections prior to death as shown by the presence of intranuclear inclusions and cytolytic effects. Placentas remained intact and viable even after resorption of attached fetuses. The health of all mother animals was unaffected. One special strain — HHP — was the only RV strain to induce transplacental infection orally in hamsters. The various attributes of these parvoviruses that make them particularly favorable agents for the study of transplacental infections are discussed.
Prolonged gestation in the rat and its usefulness in experimental teratology
Authors: Barrow Mark V. , Rowland Carol A.
Published: June 2005

After ascertaining that intrauterine growth and maturation continue when pregnancy is prolonged with progesterone in Sprague‐Dawley rats this technique was combined with the teratogens chlorcyclizine, vitamin A, and β‐aminopropionitrile (BAPN), to study the effects of 2 to 3 extra days of intrauterine growth on various abnormalities. Females were killed on day 21 or, if treated with progesterone, on day 24 of gestation. Untreated animals served as controls.

In the day‐24 chlorcyclizine group, edema and hydronephrosis were either as severe as or more marked than in the day‐21 group and the testes remained near the kidneys rather than descending deep into the pelvis. Vertebral calcification, usually not present on day 21, had occurred by day 24. These findings suggest that edema, hydronephrosis, and undescended testes were probably permanent defects, whereas lack of calcification was due to delay in occurrence. The smaller dose of vitamin A produced facial abnormalities ranging from marked underdevelopment of the mandible to relative prognathism in day‐21 fetuses but mostly prognathism in day‐24 fetuses; whereas the higher dose produced severe underdevelopment of the jaws and decrease of skeletal calcification in young of both age groups. Severe limb malformations, noted in day‐21 fetuses after high doses of vitamin A, were not grossly altered by prolonging pregnancy. BAPN‐induced limb malformations and gibbus deformities noted on day 21 were still present on day 24.
Tooth anomalies in the oral‐facial‐digital syndrome
Authors: Lauterstein Aubrey M. , Pruzansky Samuel
Published: June 2005

The relation of alveolar clefts to morphogenesis of teeth in the line of the cleft was explored. The oral‐facial‐digital (OFD) syndrome is a unique experiment of nature wherein the position of the cleft is posterior to where it occurs in the more common types of cleft. In the latter the cleft occurs anterior to the maxillary canine and affects the number and form of the lateral incisor. In the OFD syndrome the cleft occurs posterior to the canine with duplicate canines, sometimes “T”‐shaped, occurring on either side of the alveolar cleft. These findings suggest a common timespace relation between alveolar clefting and tooth‐bud formation, probably occurring in the sixth week of embryonic life.
Teratogenic effects of carotid ligation on the developing dentition of the rhesus monkey
Authors: Kraus Bertram S. , Myers Ronald E. , Clark Gerald R.
Published: June 2005

The common carotid arteries and jugular veins were bilaterally ligated in three rhesus monkey fetuses, each of 65 days gestational age, which were then restored to the uterus and allowed to reach full term. At birth the animals were killed and the tooth crowns were extracted. There were numerous morphological abnormalities of the crown and in many instances the crowns were markedly smaller than those of a nonligated series of full term offspring. Several types of the abnormalities were similar to those observed in human subjects afflicted with cleft lip and/or palate, Down syndrome (“Mongolism”), and rubella syndrome. Since rhesus monkey and human dental crowns have many developmental and morphological traits in common the use of this animal as an experimental model in the investigation of normal and abnormal crown development is indicated.
Growth of postimplantation mouse embryos cultured in a serum‐supplemented, chemically defined medium
Authors: Clarkson S. G. , Doering J. V. , Runner M. N.
Published: June 2005

The isolated mammalian embryo is a relatively unexploited developmental system for studying early somite stages: the embryonic period of greatest susceptibility to teratogenesis. The mouse embryo offers sufficient advantages for such studies that a short‐term culture procedure was adapted for early postimplantation stages (Witschi stages 14 or 15 corresponding to one to 12 somites). Criteria for growth in vitro demonstrated that quantitative determinations of DNA, RNA and protein content consistently correlated with morphological end points.

A medium comprising 20% rat serum in Waymouth's MB 752/1 supported better development and net macromolecular synthesis than did media containing 0, 10 or 100% rat serum. Embryos in the 20% serum‐supplemented medium approximately doubled their nucleic acid and protein contents during 22 hours in culture. This increase corresponds to roughly 60% of the growth of embryos in vivo and should permit biochemical investigations to be made of the early effects of teratogenic treatments.
Resorption in guinea pigs as estimated by counting corpora lutea: The problem of twinning
Authors: Hoar Richard M.
Published: June 2005

Normal pregnant guinea pigs were killed on gestation days 12–20 and examined for implantation sites and resorbing embryos. Their ovaries were removed and serially sectioned, and the functioning corpora lutea counted for comparison with the number of conceptuses.

It was found that a single corpus luteum was associated with two implantation sites with a frequency of 9.55%. Embryonic loss prior to implantation was 12.6% and the value for resorption following implantation varied from 5.8 to 7.2% depending on the time of killing and the method employed for determining resportion. A count of functioning corpora lutea facilitated the determination of embryonic loss prior to implantation, but offered little advantage over simpler techniques for determining resorption after implantation.
Correlation of embryonic movement with palate closure in mice
Authors: Walker Bruce E.
Published: June 2005

Previous experiments on palate development led to the hypothesis that neck extension and movements of the lower jaw and tongue are necessary for palate closure. To see if such movements existed at the appropriate developmental stage living embryos were studied at the time of normal palate closure. Spinal cord sections were performed on pregnant mice to permit laparotomy without sedating the embryos, the mice were partially submerged in warm saline, and embryonic movements were observed and photographed. Onset of movement coincided temporally with the onset of palate closure. In addition to movements of limbs and trunk, movements of neck, lower jaw, and tongue were also seen. Activity of embryos could be detected within the intact uterus as well as after removal from the uterus and membranes, and was inhibited by ether. The movements appeared to be spontaneous. These observations are consistent with the hypothesis that the mechanism of palate closure involves muscular movements by the embryo.
Studies of the growth‐inhibitory action of cortisone on chick embryos
Authors: Badran Amado , Provenza D. Vincent
Published: June 2005

A histological study of the action of cortisone on developing chick embryo tibial cartilage revealed that the chondrocytes were smaller and the intercellular substance was diminished. Autoradiographic experiments demonstrated less accumulation of 35S in the diaphysis of cortisone‐treated cartilage, but not in the metaphysis or epiphysis.
Teratogenic effects of vincristine in three lines of mice
Authors: Joneja M. , Ungthavorn S.
Published: June 2005

Pregnant DBA/2J, C3H/HeJ, and ICR/Ha mice were injected intraperitoneally with vincristine sulfate on day 9 of gestation. The mothers were killed on day 17 and the fetuses were examined for various defects. A high incidence of fetal mortality, congenital anomalies, and growth retardation was induced in all three types of mice. DBA's were most susceptible to the teratogenic effects of the drug. Anomalies involved the central nervous system, eyes, limbs, tail and ribs, and most fetuses had more than one anomaly. Most of the types of anomalies observed were similar to those reported in rats, but dose required to produce malformations was much higher than that reported for rats, hamsters and monkeys.
Congenital defects in guinea pigs: Prenatal retardation of brain growth of guinea pigs following hyperthermia during gestation
Authors: Edwards M. J.
Published: June 2005

Hyperthermia was induced in pregnant guinea pigs for 1 hour on 2, 4, or 8 consecutive days between days 4 and 67 of gestation. Mean newborn brainweight was reduced substantially and incidence of micrencephaly increased following hyperthermia on 4 or 8 successive days during days 15 to 32, and apparently to a lesser degree following exposure on days 39 to 46, and 53 to 60 of gestation. Maternal hyperthermia at other than these periods was associated with little or no reduction in mean brainweight or increase in incidence of micrencephaly. Following hyperthermia on 2 successive days during days 14 to 31 of gestation the incidence of micrencephaly was increased and mean brainweight decreased in offspring from females heat stressed on days 16–17, 20–21, 22–23, and 24–25. The effects of hyperthermia on brain growth were most marked on days 20–21 or 22–23. Following 1 hour of maternal heat stress on day 21 of gestation, brainweight of newborn animals was reduced if maternal body temperature was elevated more than 2.5°C above normal. For each 1°C elevation in body temperature above this level brainweight was reduced by approximately 8.4% compared with control values.
Congenital eye defects in the mouse. II. The influence of litter size, litter spacing, and suckling of offspring on risk of eye defects in C57BL mice
Authors: Pierro Louis J. , Spiggle Jean
Published: June 2005

Eye defects including corneal capacity, microphthalmia, cataract, and anophthalmia occur spontaneously in C57BL mice. Breeding experiments with substrain C57BL/10ChPr described in the present report indicated that the probability of inclusion of animals with eye defects in litters subsequent to the first is influenced by litter spacing, litter size, and suckling of offspring. Second and third litters were as likely to include progeny with eye defects as were first litters if they resulted from matings taking place after weaning of the previous litter or if the mother was prevented from suckling her previous litter. If the gestation period overlapped with suckling of young from a previous litter the resulting litter contained fewer offspring and animals with eye defects were less likely to be included. Reduction in litter size appeared to result from embryonic losses prior to the time of implantation. The prevalence of overlap between gestation and suckling of young, in matings used for stock maintenance, led to an apparent decline with increasing litter rank in the frequency of litters that included progeny with eye defects.
A model in comparative teratogenesis. II. Response to 5‐fluoro‐2‐deoxycytidine at successive stages in organogenesis of mice of strains C57BL/6JHanFfm and C57BL/10JFfm– + ld
Authors: Fränz J. , Degenhardt K.‐H.
Published: June 2005

Ten mg/kg 5‐fluoro‐2‐deoxycytidine (FCdR) was given intraperitoneally to pregnant mice of the inbred C57BL/6JHanFfm and C57BL/10JFfm‐ + ld strains once at successive stages of organogenesis. Near‐term fetuses were analyzed for gross and skeletal malformations. The following observations were made. (1) The critical period for eye defects occurred at stages IV–X with a maximum response at stages VIII:18 for C57BL/10− + ld and IX for C57BL/6. Females were more often affected than males, and right eyes more often than left. (2) The critical period for the vertebral column was at stages VI–XII with maximum response at stages IX–XI for vertebral bodies and neural arches and IX for ribs. (3) Limb primordia reacted at stages VIII:18–XII, with two peaks of maximum response at stages IX and XI. (4) Skull primordia reacted at stages VI–IX with no clear peak of maximum response. The types of malformations were described. They were found to be nonspecific for FCdR. Strain differences regarding times of maximum response were explained by the different rates of intrauterine development. Concerning the sporadic malformations seen in controls and at a higher rate and severity in the experimental series, it was concluded that FCdR changed the threshold for these genetically determined defects.
Variations in development of the caudal neural tube in human embryos (Horizons XIV–XXI)
Authors: Lemire Ronald J.
Published: June 2005

Eight human embryos of Streeter's Horizons XIV to XXI were examined with respect to variations in caudal neural tube development after closure of the posterior neuropore in Horizon XII. A major aspect of this development appears to be a process of “canalization” (accessory lumens coalescing from the differentiating caudal neural cell mass), which corresponds to such occurrences in the chick and rat. Some degree of obliteration of the central canal was found in four embryos.

The relation of these observations to clinical entities is discussed. There is suggestive evidence that open lesions of the spine may be associated with failure of closure of the posterior neuropore. In contrast, normal‐skin covered lesions probably arise from neural tube formed from the differentiating caudal cell mass after Horizon XII. This hypothesis could explain the distribution of lesions seen in newborn children.
A maternal effect on the frequency of spontaneous cleft lip in the A/J mouse
Authors: Davidson J. G. , Fraser F. C. , Schlager G.
Published: June 2005

Female mice of the inbred C57BL/6 strain were crossed to males of the A/J strain. F1 females were backcrossed to A/J males, the backcross females were crossed to A/J males, and so on for six backcross generations. In each generation a reciprocal backcross was obtained by crossing the hybrid males with A/J females. The following conclusions were drawn: (1) Spontaneous resorption in the C57BL/6 strain is determined in part by genes, recessive to their alleles in the A/J strain, which act in the mother, rather than the fetus. (2) The predisposition to spontaneous cleft lip in the A/J strain shows multifactorial inheritance. In the backcrosses, where the picture is not complicated by the maternal effect, the frequency of cleft lip reached the A/J level only in the sixth backcross. (3) In each backcross generation (hybrid mother) the cleft lip frequency was lower than in the genetically similar reciprocal backcross (A/J mother); thus the A/J mother contributes to the fetal susceptibility to cleft lip, either by providing an appropriate uterine environment or by not providing a factor, present in the C57BL strain, that decreases susceptibility to cleft lip.
Morphology and embryology of duplicitas posterior mice
Authors: Center Elizabeth M.
Published: June 2005

The duplicitas posterior syndrome, which involves both duplication and reduction of structures in the posterior region of the mouse, was investigated with reference to the morphology and embryology of its various manifestations. The four principal categories of external anomalies are (a) reduction of a hindleg, (b) reduction of a hindleg and development of an extra leg, (c) duplication of hindlimbs, and (d) kinking of the tail. The skeletal elements of the hindlimb girdle and vertebral column caudal to the thoracic region are involved. Various abnormalities of the urinary tract, male genital tract, and posterior end of the hindgut also occur. It appears from study of embryological stages of 10 to 16 days' gestation that the primary definitive effect is on the caudal end of the neural tube. Bifurcation of and apparent budding off from the primary neural tube of an accessory neural tube with accompanying limb and tail involvement are found. This doubling process may be preceded by prior subdivision of chordamesodermal tissues. The abnormalities of the urogenital and hindgut tissues are probably secondary to the duplication of axial and appendicular elements. Genetic tests indicated that the syndrome has a multifactorial basis, probably involving at least two recessive genes.
Intra‐amniotic injection of pyridine nucleotides or adenosine triphosphate as countertherapy for 6‐aminonicotinamide (6‐AN) teratogenesis
Authors: Chamberlain J. G. , Goldyne M. E.
Published: June 2005

Day‐15 rat uteri were exteriorized under ether anesthesia and 100 μg 6‐AN + 500 μg oxidized (NAD;NADP) or reduced (NADH;NADPH) coenzyme; 500 μg adenosine triphosphate (ATP); or 100 μg nicotinamide (NAM) were injected into amniotic cavities in one horn. Embryos in the opposite horn served as injection controls. Mothers were closed and returned to their stock diet until autopsy on day 21 of gestation (day 0 = day of finding spermatozoa); fetuses were weighed, fixed, and examined for congenital abnormalities. Coenzymes, ATP, and NAM appeared to correct fetal and placental weight loss observed in 6‐AN‐treated fetuses. Vitamin and coenzyme therapy but not ATP treatment reduced the frequency and severity of brain and skeletal malformations to the double puncture, solvent control value. The data suggest that malformation and mortality may involve separate mechanisms.
Effect of mimosine on the rat fetus
Authors: Dewreede Sharon , Wayman Oliver
Published: June 2005

Groups of 16 pregnant rats per treatment were fed ad libitum a basal diet containing 0, 0.3, 0.5, or 0.7% mimosine or allowed a restricted intake of the diet with no mimosine until killed on day 20 of gestation.

Incremental increases of mimosine caused significant (P<0.01) decreases in daily feed consumption, weight gain per unit of food, and total weight gain. A significant (P<0.01) increase in fetal resorption, but no difference in mean conceptuses per litter, was associated with 0.7% mimosine. Fetal deformities due to constriction of localized parts occurred in litters from females fed 0.5 and 0.7% mimosine. Deformities were associated with perforations in the uterus between placental attachments with partial protrusion of fetuses through the uterus.

Most sacral vertebrae were missing in fetuses of females fed 0.7% mimosine and of restricted intake controls. There were no differences in hematocrit values due to treatment.
The alteration of actinomycin D teratogenicity by hormones and nucleic acids
Authors: Elis J. , DiPaolo J. A.
Published: June 2005

Actinomycin D (act D) was teratogenic to Syrian hamsters. The most effective dosage, 200 μg/kg of body weight, produced malformations when injected on day 4, 6, 8 or 10 of gestation. 100 μg/kg produced malformations only after injections on day 6 or 8. 300 μg/kg was strongly embryolethal, but some malformed fetuses were found among live survivors. 400 μg/kg caused 100% maternal lethality. The teratogenicity and fetal and maternal lethality were reduced when act D was mixed with nucleic acids. DNA was more potent than RNA in preventing toxic effects of act D. The embryolethal effect of act D was also diminished by treatment with a combination of 4 mg progesterone and 1 μg of estrone, although maternal lethality and teratogenicity were not prevented.
Cleft palate in A/J mice resulting from restraint and deprivation of food and water
Authors: Rosenzweig Sanford , Blaustein Frances M.
Published: June 2005

A/J mice were subjected to restraint and/or food and water deprivation for 24 or 48 hours beginning on day 14 of pregnancy. The 48‐hour treatment sharply increased the cleft palate and resorption rates. The data strongly suggest that restraint can cause cleft palate if imposed for an extended period of time.
Breeding and pregnancy in rhesus monkeys used for teratological testing
Authors: Wilson James G. , Fradkin Rochelle , Hardman Alvin
Published: June 2005

Fifty‐two young rhesus females were bred intensively under laboratory conditions for 6‐24 months. More than half became pregnant by 90 days after first observed menstruation, and all of an original group of 37 became pregnant by 2 years. A rate of 1.2 pregnancies per female per year was achieved by interrupting pregnancy by hysterotomy at day 100 and rebreeding the female within 1 to 2 months. Further improvement on this rate is a reasonable expectation.

After hysterotomy menstruation usually resumed by 30–50 days. Second pregnancies occurred in 80% of 28 females by 9 months and in all by 16 months.

Accurately anticipating the time of ovulation is unresolved, but estimation of chloride content of cervical mucus has permitted more effective breeding in some cases than would have been possible by routine breeding on days 11‐13 of the menstrual cycle. Clomiphene citrate did not improve conception rate in relatively infertile animals above that observed in untreated animals with similar reproductive histories.

A biological pregnancy test was developed that can be completed in 24 hours, can diagnose pregnancy as early as day 16, and is highly reliable by day 20 of gestation. Early abortions after teratological tests were diagnosed by uterine palpation.

The 100‐day fetus proved entirely satisfactory for evaluation of anatomical development.
Trypan blue and the extra‐toes locus in the mouse
Authors: Johnson D. R.
Published: June 2005

Trypan blue and the extra‐toes gene (Xt) in the mouse produce syndromes with many abnormalities in common. Treatment of litters segregating for Xt with trypan blue increases the expressivity of the gene. Gene and teratogen act additively in most cases but interacted in one case. It is suggested that both gene and teratogen act by retardation of developing embryos.
Repair of the external granular layer of the hamster cerebellum after prenatal and postnatal administration of methylazoxymethanol
Authors: Shimada Morimi , Langman Jan
Published: June 2005

The purpose of this experiment was to examine the influence of methylazoxymethanol acetate (Mam ac) on cell proliferation and regeneration of the external granular layer in the cerebellum of the hamster. Pregnant hamsters were treated with 10 mg/kg/day Mam ac on days 13–15 of gestation and youngsters on the second, third, and fourth or fourth, fifth and sixth postnatal days. In animals treated during intrauterine life and examined on the day of birth a large number of cells in the external granular layer were destroyed, but some seemingly healthy ones always remained. In those permitted to live, surviving cells formed a new external granular layer and by the 20th postnatal day no morphological differences could be detected between the treated and control animals. In animals treated on the second to fourth postnatal days practically all the cells of the external granular layer were destroyed. By the tenth day the Purkinje cells were located throughout the molecular zone. Many of them showed a cytoplasmic cone extending centrally instead of toward the periphery. The internal granular layer contained only a few cells, apparently owing to failure of the normal inflow of neurons from the external granular layer. In animals treated on the fourth to sixth postnatal days most cells in the external granular layer were destroyed. During the following days surviving cells presumably gave rise to a new external granular layer. The cells of this layer failed to migrate centrally. Instead they remained located in the molecular layer where they formed an extra layer of cells, which had the appearance of granule cells. The animals were ataxic, although retinal abnormalities may have been partially responsible for the symptoms.
Cardia bifida in chick embryos: Anterior and posterior defects produced by transplanting tritiated thymidine‐labeled grafts medial to the heart‐forming regions
Authors: Rosenquist Glenn C.
Published: June 2005

Anterior and posterior cardia bifida were produced in chick embryos by transplanting tritiated thymidine‐labeled grafts into host embryos, anterior to the anterior end of the streak and medial to the heart‐forming mesoderm, i.e., into areas destined for ventral gut or yolk sac. Anterior cardia bifida resulted when the nonintegrated part of the graft prevented the splanchnic folds from meeting at the midline to form the anterior end of the heart; this anomaly always appeared without corresponding anomalies in the endoderm and ectoderm layers. Posterior cardia bifida resulted when the part of the graft that had not been integrated into the host tissue interfered with the formation of the foregut. The position of the labeled cells in the endocardium, myocardium, mesocardium, endoderm, and yolk sac was determined by radioautography. Although cardia bifida has no known counterparts in the pathological anatomy of human congenital heart disease, study of the condition gives significant insight into the relations of the primary germ layers.
The embryolethality and localization of antikidney serum in the pregnant mouse, Mus musculus
Authors: Gebhardt D. O. E. , de la Faille‐kuyper E. H. Baart , Nagel J.
Published: June 2005

The period in which antimouse kidney serum (AKS) was embryolethal in the mouse extended from days 4–15 of pregnancy. The highest sensitivity toward AKS existed at days 10–14.

When AKS was localized in the uterus by immunofluorescence the following results were obtained. On day 10 Reichert's membrane, parietal yolk‐sac cells, and endodermal cells of the visceral yolk sac, but not the embryo, showed intense fluorescence. By day 12 Reichert's membrane and the parietal yolk‐sac cells had lost most of their immunofluorescence. The visceral yolk‐sac cells adjacent to the chorioallantoic placenta still stained strongly on day 18 of pregnancy.

AKS from which the antiplacental factor(s) were removed retained its embryolethality when injected on day 10. It was localized solely in the visceral yolk sac. Therefore AKS probably caused embryonic death by damaging the yolk‐sac cells.

Only during the last days of pregnancy was there any transfer of AKS to the embryos.
Development of explanted rat fetuses in hyperbaric oxygen
Authors: New D. A. T. , Coppola P. T.
Published: June 2005

Raising the oxygen pressure of the culture chamber to 2 or 3 atmospheres improved the development in static serum of rat embryos explanted at 11.5 days' gestation, but the final stage attained (35–37 somites) was less than that of embryos in circulating serum equilibrated with oxygen at normal pressure (40–45 somites). Hyperbaric oxygen appeared to be of most value for the culture of embryos explanted at 12.5 days' gestation (about 40 somites). These developed well to 50–55 somites in circulating serum in oxygen at two atmospheres pressure, but showed very little development in oxygen at normal pressure. The high oxygen concentrations were harmful to the yolk sac, and it was not possible to extend development in culture beyond 50–55 somites.
Teratogenic compounds of Veratrum californicum (Durand). X. Cyclopia in rabbits produced by cyclopamine
Authors: Keeler Richard F.
Published: June 2005

Cyclopamine, the compound responsible for cyclopia in sheep upon maternal ingestion of Veratrum californicum, produced cyclopia and related cephalic malformations in rabbits when orally administered with CaCO3 as a stomach‐acid buffer to prevent acid‐induced conversion to veratramine, a compound devoid of similar teratogenic activity. The insult period was between days 6 and 9 of gestation. Both in vitro and in vivo experiments suggested the conversion of nonbuffered cyclopamine to veratramine under stomach‐acid conditions.
Effects of transitory maternal pteroylglutamic acid (PGA) deficiency on levels of adenosine phosphates in developing rat embryos
Authors: Chepenik Kenneth P. , Johnson E. Marshall , Kaplan Stanley
Published: June 2005

A transient maternal folic acid deficiency resulted in alterations in the concentrations of adenosine triphosphate (ATP), diphosphate (ADP), and monophosphate (AMP) in developing rat embryos. At the end of the treatment period the ATP level was markedly reduced and the pool of adenine (as ATP, ADP, and AMP) was decreased in experimental embryos. On the basis of these findings an explanation is suggested for the increased oxygen consumption previously observed for rat embryos from folic acid‐deficient females.