bluuebunny/crossref_metadata_2025 huggingface dataset:
Aortic aneurysm associated with cardiac defects in theophylline stimulated chick embryos
Authors: Ishikawa Shizen , Gilbert Enid F. , Bruyere Harold J. , Cheung Matthias O.
Published: June 2005

Theophylline (1 ml 0.02 M in 0.15 M saline) was administered to embryonic chicks (Hamburger‐Hamilton developmental stages 24–27). The drug was topically applied to the surface of the chorioallantoic membrane in the vicinity of the embryonic heart.

At necropsy, 63% (44/70) of the theophylline‐exposed embryos demonstrated an aneurysm in the ascending aorta.

Among the cases exhibiting aortic aneurysm, 48% (21/44) of the embryos demonstrated ventricular septal defects. Four cases of truncus arteriosus were also observed.

The morphogenesis and mechanism of theophylline‐induced cardiac defects with accompanying aortic aneurysm may be related to the development of the conotruncal region of the heart.
Teratogenic potential of blighted potato concentrate in rabbits, hamsters, and miniature swine
Authors: Sharma R. P. , Willhite C. C. , Wu M. T. , Salunkhe D. K.
Published: June 2005

Freeze‐dried preparations of potatoes infected with Phytophthora infestans or Alternaria solani were fed to pregnant hamsters, rabbits, and miniature swine. No evidence was observed that these diets or the extracts of respective blights were capable of producing teratologic effects in hamsters. Lesions of neurulation and anencephaly were noticed in rabbits and swine, respectively. The need for further pharmacological and toxicological evaluation in sensitive species is emphasized.
The morphogenesis of β‐aminopropionitrile‐induced rib mal formation in fetal golden syrian hamsters
Authors: Wiley M. J. , Joneja M. G.
Published: June 2005

In order to provide information on the mechanism of β‐aminopropionitrile (βapn) induced teratogenesis, the pathogenesis of a fetal rib abnormality was studied at relatively short time intervals following maternal treatment with 2,500 mg/kg aqueous βapn on day 11 of gestation. Histochemical tests of ribs from βapn‐exposed fetuses indicated a slight decrease in the level of glycosaminoglycans but at a time when the defect was already morphologically established. Ultrastructural observations on the chondrocytes of ribs from βapn‐exposed fetuses revealed alterations in mitochondrial structure indicative of a slight cytotoxic effect for the teratogen. The mitochondrial changes were transient, occurring initially at three hours after treatment and lasting for nine hours. Alterations in the size of collagen fibres in the cartilage of the fetal rib were also observed in the offspring of βapn treated females. The mean diameter of collagen fibres in the ribs of control fetuses increased throughout the course of the study. The mean diameter of fibres in the fetuses of βapn‐exposed females failed to show any increase and was found to be significantly less than controls as early as three hours following maternal administration. The results suggested that the principal factor in the production of the fetal rib deformity was fundamentally the same as that known to affect the adult; namely a defect in the extracellular maturation of collagen.
Effect of 4‐methylumbelliferyl‐β‐D‐xylopyranoside on the morphology of embryonic cartilage in limb bud cultures
Authors: Merker H.‐J. , Günther Th. , Krüger U.
Published: June 2005

Limb buds of 11‐day‐old mouse embryos were cultured for six days in the presence of 0.1, 0.5 or 2 mg/kg 4‐methylumbelliferyl‐β‐D‐xylopyranoside. A dose‐dependent decrease in chondrogenesis could be observed in preparations stained with methylene blue and cleared. A reduction or even disappearance (after 2 mg/kg) of intercellular spaces and a change in shape and size of chondroblasts was striking in the light microscopical picture. The electron microscopical findings reveal a decrease in the number, size, and electrondensity of the ruthenium‐red‐positive proteoglycan granules as well as an alteration in the collagen morphology. Up to 1,000 Å thick fibrils occur which partly show a so‐called continuous cross‐striation. In addition, bundles of thin (50–100 Å) collagen filaments without cross‐striation occur. The number, distribution and packing density of the cell organelles in the chondroblasts are very variable. The vacuoles of the Golgi apparatus are dilated. These effects may be attributed to the xyloside‐induced alterations of proteoglycans.
Toxicity of ethylenethiourea in pregnant cats
Authors: Khera K. S. , Iverson F.
Published: June 2005

Ethylenethiourea (ETU) was administered orally in single daily doses of 0, 5, 10, 30, 60 or 120 mg/kg to time‐mated cats. Daily dosing was started on day 16 of gestation in all test groups and was discontinued on the appearance of toxicity signs (between days 27–34 of gestation) in the 120 mg/kg group and on day 35 of gestation in the remaining test groups. Signs of toxicity, observed at all dose levels except in the 5 mg/kg and control, were delayed in onset and characterized by progressive loss in body weight, ataxia, tremors and hind‐limb paralysis. A number of cats died or were killed in a moribund condition in the 30, 60 and 120 mg/kg dose groups. Eleven of the thirty‐five fetuses obtained from six cats killed in a moribund state (4 from the 30 mg/kg and 1 each from the 60‐ and 120 mg/kg groups) were malformed, with coloboma occurring in four fetuses, cleft palate in two, spina bifida in one and umbilical hernia in four fetuses. Incidences of abortion and non‐pregnancy, both unrelated to the treatment, were found in all groups including the control. All surviving cats were necropsied on day 46 of gestation and fetuses were collected for teratologic evaluation. No clear evidence was found for teratogenicity of ETU in live fetuses.
Embryotoxic effects of methylmercuric chloride administered to mice and rats during organogenesis
Authors: Fuyuta Masatoshi , Fujimoto Toyoaki , Hirata Shuichi
Published: June 2005

Pregnant C57BL mice were given a daily dose of 7.5, 6.0, 5.0 or 2.5 mg/kg methylmercuric chloride (MMC) orally from the sixth through the thirteenth day of pregnancy. Pregnant Wistar rats were given a daily dose of 7.5, 5.0 or 2.5 mg/kg MMC orally from the seventh through the fourteenth day of pregnancy. Fetal examinations were performed on days 18 and 20 in mice and rats, respectively. In mice, the dose of 7.5 mg/kg was embryocidal. The dose of 6.0 mg/kg also caused a high incidence of fetal death, decreased fetal weight and a marked increase in malformations. A dose of 5.0 mg/kg caused a decrease in fetal weight and a marked increase in the incidence of malformations. The most common malformations were cleft palate and fused thoracic vertebrae. In rats, the dose of 7.5 mg/kg caused a high incidence of fetal death and malformations. The most frequent malformations were cleft palate, generalized edema, brain lesions and wavy ribs. A dose of 5.0 mg/kg caused a significant decrease in fetal weight and a significant increase in the incidence of malformations.
Teratogenic action and embryo lethality of AY 9944R: Prevention by a hypercholesterolemia‐provoking diet
Authors: Roux Charles , Horvath Cécilia , Dupuis Rolande
Published: June 2005

Embryomortality and teratogenesis provoked by inhibitors of cholesterol synthesis are well demonstrated. Teratogenic action is particularly reflected by holoprosencephalies, but also by uro genital abnormalities. A hypercholesterolemia‐provoking diet has been shown to be completely effective for preventing holoprosencephaly, but only partially so for preventing the urogenital malformations and fetal mortality. It is thus possible that the two types of abnormalities are governed by different mechanisms. In addition, the diet itself, whose hypercholesterolemic effect is considerable, has certain disadvantages. It seems to have a certain effect on fetal mortality and could be responsible for several uro‐genital malformations. This deserves further study.
Abnormal circulatory development in medaka caused by the insecticides carbaryl, malathion and parathion
Authors: Solomon Howard M. , Weis Judith S.
Published: June 2005

Three insecticides, carbaryl, malathion and parathion were tested for teratogenic effects in developing medaka eggs. The concentrations of insecticides ranged from 0.5 to 40.0 parts per million (ppm). The insecticides, dissolved in acetone, were added to dishes containing 10 newly fertilized eggs and 10 ml of embryo rearing solution. Circulatory anomalies which resulted in‐cluded defects in heart morphology, pericardial edema, irregular heart beat, blood clots and oscillating blood in the heart. The ED50 (effective dose) for cabaryl was 2.5 ppm; malathion, 10.0 ppm and parathion, 2.0 ppm.

Limited exposure experiments were undertaken to determine possible sensitivity periods during development. These experiments, using 10 ppm carbaryl were initiated on days 0–7. Exposure lasted 24 to 96 hours. No periods of sensitivity were observed in these experiments. In a slightly varied experiment, eggs developed normally for 0–5 days, but were not removed from the insecticide once exposed. These results showed that carbaryl could cause circulatory abnormalities in 92% of the embryos which had completed cardiac morphogenesis before exposure.

Combinations of malathion and carbaryl were administered to determine possible interactions. Twenty‐five different combinations ranging from 0.0 to 25.0 ppm were employed. At low concentrations, combinations had slightly greater than additive effects. At higher concentrations additive and antagonistic effects were observed.

The above experiments show that (a) these insecticides are teratogenic, (b) carbaryl at 10 ppm does not disrupt developmental events but rather affects‐cell physiology and (c) combinations of some insecticides have an additive effect.
Prevention by diazepam of adverse effects of maternal restraint stress on postnatal development and learning in the rat
Authors: Barlow S. M. , Knight A. F. , Sullivan F. M.
Published: June 2005

Rats on days 12–14 of pregnancy were treated with restraint stress alone (9h daily), restraint stress plus diazepam (1 mg/kg, twice daily), diazepam alone, or left as untreated controls. Postnatal development and behaviour was assessed on a wide‐ranging battery of tests. Offspring of mothers subjected to restraint stress alone were significantly retarded on a number of developmental measures including growth, ear‐opening, cliff avoidance response, auditory startle response and mid‐air righting reflex. When adult these offspring also showed significantly impaired learning ability in a swimming maze. However, the rate of development and learning ability in the restraint plus diazepam or diazepam alone groups was comparable to or slightly advanced of that in untreated controls. It is concluded that concurrent administration of a low dose of the tranquiliser diazepam during restraint stress prevents the adverse postnatal effects of maternal restraint stress.
Prune belly syndrome and fetal ascites
Authors: Monie Ian W. , Monie Barbara J.
Published: June 2005

A case of prune belly syndrome (PBS) in a 22 week male fetus is described. All the features characteristic of the syndrome were present: absence of abdominal muscle; dilatation of the bladder, ureters, and renal pelves; and undescended testes. In addition, there was marked ascites. The rectus abdominis muscles were entirely absent whereas other abdominal muscles were only absent centrally. Between regions of normal and absent musculature muscle fibers were sparse, enlarged, frequently disrupted, and mostly in the myotubule stage. The prostate was thin‐walled and its urethra greatly expanded. The testes lay close to the corresponding ureters and each ductus deferens was only partially present. It is considered that prostatic dysgenesis and fetal a'scites are key factors in the causation of PBS.
In vitro metabolism of cyclophosphamide in limb bud culture
Authors: Manson Jeanne M. , Simons Ruth
Published: June 2005

The presence of a drug‐metabolizing system in any in vitro bioassay for teratogenicity is necessary because many chemical agents require metabolism before their activity can be expressed, and limb bud cells lack the enzymes necessary to activate these chemicals. We have taken three approaches to add a drug‐metabolizing system to limb bud culture; addition of a 9,000 × g supernatant (S9) or a purified microsomal fraction, both from mouse liver, and co‐incubation of limb buds with hamster embryo cells (HEC). The liver preparations were able to convert the teratogen cyclophosphamide to five separate metabolites with alkylating activity in limb bud culture but the cytotoxicity of these preparations limited their usefulness as metabolizing systems in limb bud culture.

HEC did not exert a toxic effect on limb buds and they were able to continue metabolism of cyclophosphamide for three days. Analysis of the metabolites indicated that HEC did not convert cyclophosphamide to the same products as the liver preparations. The metabolic products were capable of inducing abnormal limb development in vitro. Addition of 14C‐cyclophosphamide in the presence of an HEC activating system led to uptake of radioactivity into limb buds. In the absence of HEC, little radioactivity was detected in the target tissue. These results suggest that culturing intact cells capable of drug metabolism with limb buds may be the most likely method to follow in achieving in vitro activation of chemicals.
Equivalent ages in rat, mouse and chick embryos
Authors: Schneider Bernard F. , Norton Stata
Published: June 2005

Data for estimating equivalent ages of rat, mouse and chick embryos are presented, using several sources from the literature. When the time of development of various embryonic structures is matched for the three species, the differences in time for the stages are primarily due to delays in development of the preimplantation blastulas of the rat and mouse in comparison with the incubated chick egg. Development from the blastula stage to completion of major organogenesis proceeds at approximately the same rate for all three species.
Unusual muscle abnormalities associated with thalidomide treatment in a rhesus monkey: A case report
Authors: Theisen Charles T. , Bodin Jeffery D. , Svoboda James A. , Pettinelli Michael W.
Published: June 2005

Unusual musculotendinous abnormalities were observed in the forelimbs of a rhesus monkey treated prenatally with thalidomide (10 mg/kg maternal body weight, gestation days 33, 34, and 35). Although the hindlimbs exhibited malformations typical of thalidomide dysmelia, the forelimbs appeared relatively normal externally. However, dissection revealed totally anomalous insertions of preaxial muscles of both forearms. Extensor muscles inserted on flexor surfaces even though normal sites of insertion were present and unoccupied. Radiographs revealed only minor ossification deficiencies in the carpus and distal radius. These observations suggest that thalidomide, given at the appropriate time, can disrupt condensation and splitting of pre‐muscle masses without greatly disturbing condensation of corresponding pre‐skeletal elements. These types of musculoskeletal relationships are unusual findings in congenital malformations of the limbs and have not been widely associated with thalidomide teratogenesis.
Selective proliferation and accumulation of chondroprogenitor cells as the mode of action of biomechanical factors during secondary chondrogenesis
Authors: Hall B. K.
Published: June 2005

Secondary cartilage fails to differentiate on membrane bones of embryonic chicks which have been paralyzed by the in ovo injection of Dtubocurarine chloride at ten days of incubation. A planimetric analysis of serial sections of a membrane bone (the quadratojugal) from control (mobile), and from paralyzed embryos, indicated that osteogenesis was not slowed in paralyzed embryos. However the rate of accumulation of periosteal progenitor cells was significantly lower in paralyzed than in mobile embryos. Quantitative analysis of 3H‐thymidine‐labelled progenitor cells indicated that the slowed accumulation of progenitor cells was the result of fewer progenitor cells initiating DNA synthesis and mitosis. Between 10 and 11 days of incubation, 60 to 75 more 3H‐thymidine‐labelled progenitor cells accumulated in mobile embryos than accumulated on each quadratojugal in paralyzed embryos. This subpopulation of cells could represent the chondroprogenitor cells which produce secondary cartilage in mobile embryos. If this is so, then biomechanical factors control the ability of the embryo to produce secondary cartilage by allowing the selective accumulation of chondrogenic progenitor cells.
The history of the A family of inbred mice and the biology of its congenital malformations
Authors: Kalter Harold
Published: June 2005

The A family of inbred mice which originated in 1921, came during its early development to have incorporated into its genome the tendency to several congenital malformations, among them cleft lip and palate. These sporadic abnormalities are of interest because they closely resemble their human counterparts in morphology and development, and because they share with them a multifactorial basis. The origins and development of the A family are traced, and the abnormalities are described and the forces affecting them detailed.
Palate morphogenesis. III. Changes in cell shape and orientation during shelf elevation
Authors: Babiarz Bruce S. , Wee Elizabeth L. , Zimmerman Ernest F.
Published: June 2005

The process of palate shelf elevation has been analyzed by light microscopy in mouse embryos cultured in vitro. The observations presented correlate changes in cell shape and orientation in the palate with the morphogenetic movement of the shelf. These studies suggest that in addition to any physical‐chemical force elevating the shelf an active contraction of specific palate cells could also aid the process. Contribution to elevation could be derived from masses of contracting cells from the previously described non‐muscle contractile systems in posterior (region 2) and mid‐anterior (region 3) palate as well as other peripheral mesenchymal cells. Finally, elongation and contraction of the tongue side epithelial cells may also play a role in palate elevation.
Muscular and other abnormalities in a case of Edwards' Syndrome (18‐trisomy)
Authors: Aziz M. Ashraf
Published: June 2005

This paper describes the anatomical variations observed in a specimen exhibiting Edwards' Syndrome (18‐trisomy). The clinical and autopsy data are compared with those reported in earlier literature. Aside from having a tracheoesophageal fistula, the viscera were characterized by abnormalities of the heart, lungs, liver and kidneys.

The facial musculature was relatively undifferentiated. Only a few abnormalities were recorded in the otomandibular and suprahyoid structures. The infrahyoid region had three pairs of supernumerary muscles, including the “sternohyoideus azygos.”.

The bulk of abnormalities were found in the muscles and nerves of the upper limb. These included the absence of the palmaris longus and brevis, the subclavius and the extensor digiti quinti proprius; the presence of supernumerary muscles, e.g., the “rhomboideus occipitalis,” the “latissimocondyloideus,” and the “subclavius posticus.” The deltoid and the pectoralis major were fused to form the “deltopectoral” complex. A definitive musculocutaneous nerve was found in the right arm only.

In the lower extremity supernumerary muscles included the “tenuissimus,” “peroneus quinti digiti,” and the “extensor primi internodii hallucis”.
Neural tube closure defects caused by papaverine in explanted early chick embryos
Authors: Lee H. , Nagele R. G.
Published: June 2005

Papaverine (50 μg/ml) preferentially inhibited uplifting of neural folds in explanted stage 8 chick embryos. Affected neuroepithelial cells often lost their wedge‐shaped and elongated appearance. Also, luminal surfaces of most affected cells were smoother than usual as evidenced by the marked decrease in the number of cytoplasmic extensions, but the integrity of other structures (including cytoskeletal components) was noticeably affected. The observed changes in cell surface topography were due, at least in part, to the impaired ability of apical microfilaments to contract and their eventual relaxation. The “relaxing” effect of papaverine on neural folds could be reversed by subsequent treatment with ionophore A23187. Since papaverine and ionophore A23187 are known to alter the normal distribution of intracellular Ca2+ and changes in cell surface topography are correlated with contractile activities of apical microfilaments, papaverine elicits neural tube closure defects by lowering intracellular free Ca2+ levels, thereby relaxing contracted apical microfilaments in neuroepithelial cells.
A teratogenicity study on hydroxyurea and diphenylhydantoin in cats
Authors: Khera K. S.
Published: June 2005

Hydroxyurea, an antitumor drug and known teratogen in rat, miniature swine and dog, and diphenylhydantoin, a teratogen in mouse and rat, were assessed for teratogenic effects in cat. Pregnancies were induced, by synchronizing gonadotropin‐stimulated estrus and ovulation with natural copulations. Hydroxyurea at 50 or 100 mg/kg, and sodium diphenylhydantoin at 1 or 2 mg/kg dosages, were administered orally in single daily doses from gestation days 10–22. Appropriate controls given empty capsules, were included for each drug. Cats were necropsied on gestation day 43. Fetuses were examined for external, visceral and skeletal malformations. Hydroxyurea at 50 mg/kg dose produced a low teratogenic activity and at 100 mg/kg a high incidence of non‐pregnancy and resorptions with, consequently, fewer live fetuses. Diphenylhydantoin gave no clear evidence of teratogenicity at any test dose but was embryolethal at the maternally toxic dose of 2 mg/kg. So far, studies conducted suggest that the cat is a useful species for screening drugs and chemicals for their teratogenic potential.
Teratogenic potential of phencyclidine in the mouse
Authors: Marks T. A. , Worthy W. C. , Staples R. E.
Published: June 2005

Pregnant CD‐1 mice were given phencyclidine by gavage on days 6–15 of gestation, at dose levels of 60, 80, 100, and 120 mg/kg/day. The mice were killed on day 18 and the offspring were examined for external, visceral, and skeletal alterations. There was a significant increase in the average percent of malformed fetuses per litter only at the 120 mg/kg/day dose level (6.1% versus 1.2% for the control), a dose level which resulted in the death of 8 of 18 dams before scheduled sacrifice. At dose levels less than 120 mg/kg/day, the incidence of malformations was not significantly higher than the control value, in spite of the presence of overt maternal toxicity. Because a significant number of malformations was not seen at dose levels which were not highly toxic to the dams, it was concluded that phencyclidine was not demonstrated to be a teratogen in the mouse.
Proximal 14 trisomy 46, XX, −22+der(14)t(14;22)(q21;q11)mat
Authors: Fried K. , Goldberg M. D. , Rosenblatt M.
Published: June 2005

A firstborn newborn female was noticed to have dysplastic folded ears, odd facies, small palpebral fissures, peculiar shape of mouth and nose, clinodactily, broad chest, and short neck. Her karyotype was 46, XX, −22+der(14)t(14;22) (q21;q11)mat. Her mother was a de novo balanced reciprocal translocation carrier. The infant was the product of the rather rare adjacent 2 form of segregation. Follow‐up of the infant to the age of 19 months revealed severe mental retardation. The syndrome of proximal 14 trisomy can be suspected on clinical grounds in the newborn.
Embryo transfer in the analysis of teratological responses of mice: A critical examination
Authors: Takano Kiichi , Biddle Frederick G. , Peterson Alan C. , Miller James R.
Published: June 2005

Although the technique of embryo transfer has been used extensively in preimplantation mammalian embryology, its role in experimental teratology will probably be quite. This statement is based on the authors' personal experience, a review of other studies employing the technique, and a reexamination of certain fundamental principles of teratology. The experiment reported here involved cleft palate induced by triamcinolone acetonide in the SWV (sensitive) and C57BL/10J (less sensitive) strains of inbred mice. Despite technical success in transferring embryos between the two strains, the cleft palate results were not consistent with those of the natural mating studies and were inconclusive. In contrast, fetal death due to triamcinolone was strongly nfluenced by the genotype of the famale, in both natural and embryo transfer pregnancies.
Hydrocephalus induced by N‐nitrosoethylenethiourea in the progeny of rats treated during gestation
Authors: Khera K. S. , Iverson F.
Published: June 2005

Ethylenethiourea (ETU), as result of degradation of ethylenebisdithiocarbamate fungicides, is often found in ingested foods. The interaction in vivo of ETU with the food preservative, sodium nitrite, may be expected to form N‐nitrosoethylenethiourea (NO‐ETU). To evaluate the pre‐ and postnatal effects of NO‐ETU in Wistar rats, single oral doses were administered: 120, 160, 200, and 240 mg/kg on day 13 of pregnancy in the prenatal study, and 60 and 120 mg/kg on day 15 of pregnancy in the postnatal study. In the prenatal study, the 200 and 240 mg/kg doses were maternally lethal, and the 120 and 160 mg/kg doses produced high incidences of malformed fetuses with hydrocephalus, exencephaly, hypoplastic cerebellum, hydronephrosis, and other anomalies. In the postnatal study, the 60 and 120 mg/kg doses were associated with hydrocephalus and microphthalmia.
A study of cartilaginous fusions, DNA synthesis, and protein synthesis in embryonic rat limbs after injection of aminothiadiazole
Authors: Wotring Glenn E. , Beaudoin Allan R.
Published: June 2005

Sprague‐Dawley rats were injected with 2‐amino‐1,3,4‐thiadiazole (ATDA), 100 mg/kg ip, on one of days 10–14 of pregnancy (sperm day = day 0). A supplementary ip injection of nicotinamide (N), 100 mg/kg, was administered to some rats immediately after the ATDA injection on day 12. Embryonic deaths, reduction limb malformations, and depressed fetal weights were attributable to ATDA treatment, but N coadministration was protective. Fetuses from rats dosed with ATDA or ATDA+N on day 12 were recovered on day 18 or 19 and their skeletons stained with methylene blue. Abnormal cartilaginous continuities or “fusions” between the various cartilage skeletal elements were present in 99% of limbs in the ATDA‐treated group. Extent of the fusions varied widely. In the forelimb, fusions occurred only in the carpus and paw, whereas in the hindlimb, there were many abnormal fusions of the tibia and fibula in addition to the fusions in the tarsus and paw. Cotreatment with N prevented fusions. Other rats treated on day 12 were sacrificed 4, 10, 24, 48, and 72 hours later. Embryonic limbs were cultured in vitro for two hours in a medium containing 3H‐thymidine or 14C‐leucine. Isotope incorporation was determined. Ten hours after treatment with ATDA, DNA synthesis was depressed to 1.2%–5.1% of control levels. By 72 hours, the rate of synthesis returned to normal. N coadministration was protective against the ATDA‐induced depression of DNA synthesis at 10 hours. Some changes in the rate of protein synthesis after ATDA treatment were apparent.
The effect of triamcinolone on the development of the bursa of fabricius in chick embryos
Authors: Fisher Cynthia J. , Sawyer Roger H.
Published: June 2005

Triamcinolone acetonide (TAC), a long‐acting synthetic glucocorticoid, markedly reduces survival rates in chick embryos when injected in small (10–100 ng) single‐injection doses on days 5 or 9 of incubation. In addition to its embryotoxic effect, TAC causes such gross malformations as gastroschisis, reduced body weight, encephalocele, micrognathia, curled toes, and club feathers. These effects of TAC are more severe in 5‐day‐old chick embryos than in 9‐day‐old ones. A comparison with cortisol (hydrocortisone), a structurally similar, naturally occurring steroid, indicates that TAC is approximately 600 times more toxic in chick embryos than cortisol. TAC also inhibits differentation of the bursa of Fabricius: single injections on the chorioallantoic membrane (CAM) of 10–20 ng on day 5 or 9 reduced size and weight of this lymphoid organ. Histological examination showed a sharp reduction in the size and number of bursal follicles, a reduction in the number of lymphocytes within these follicles, and a degeneration of the epithelium covering bursal plicae.
Craniofacial and central nervous system malformations induced by triamcinolone acetonide in nonhuman primates: I. General teratogenicity
Authors: Hendrickx A. G. , Pellegrini M. , Tarara R. , Parker R. , Silverman S. , Steffek A. J.
Published: June 2005

Eighteen pregnant Macaca mulatta, 15 Macaca radiata, and six Papio cynocephalus were treated with 5–20 mg/kg triamcinolone acetonide (TAC) between 21 and 43 days of gestation on single‐ or multiple‐day treatment schedules. Prenatal deaths and stillbirths were tripled in the bonnet monkey and doubled in the rhesus monkey, but did not significantly increase in the baboon. The central nervous system and cranium were the most commonly malformed areas in all three species. The incidence of severe defects, e.g., cranium bifidum, encephalocele, meningocele, and hydrocephalus, was increased in multiple‐day treated cases. Minor abnormalities such as aplasia cutis congenita, cranium bifidum occultum, and occipital lobe hypoplasia were more prevalent in single‐day treated cases. The sensitive period (days 23–31) for TAC for this group of defects encompasses neural tube closure, rostral demarcation of the midbrain, and development of the primordial collicular plate and two midbrain neuromeres. The results of this study indicate that TAC is a valuable chemical tool for the study of malformations and pathogenesis of the brain and accompanying craniofacial defects.
Cardiovascular alterations in rabbit embryos in situ after a teratogenic dose of hydroxyurea: An in vivo microscopic study
Authors: Millicovsky Guillermo , DeSesso John M.
Published: June 2005

The early cardiovascular (CV) responses of New Zealand white rabbit embryos in situ subsequent to maternal SC injection with hydroxyurea (HU) were analyzed by in vivo microscopic methods. Laparotomies were performed on gestational day 12, and the gravid uteri were exteriorized. The embryos were exposed by careful incisions of the uterine wall and reflection of the extraembryonic membranes. Temperature, water, and electrolyte homeostasis were maintained throughout all procedures. Maternal injection with HU at a teratogenic level (750 mg HU/kg) caused alterations in the embryonic CV system as early as 2 minutes post‐treatment. Typically, within 4 minutes the embryonic craniofacial region responded with dilations of the anterior cardinal vein (ACV) and its tributaries. The ensuing pathological events included petechial hemorrhages and hematomas in the forebrain, postocular region, mandibular and nasal processes, and apparent collapse of the vasculature in the forelimb bud. Many embryos exhibited pericardial hemorrhage within 9 minutes. The most severly affected embryos displayed cardiac tamponade and stasis of blood flow through the cardiac chambers. In contrast, control embryos, which received either no drug treatment or SC injection of saline at various osmolarities and pH's, demonstrated none of the CV changes reported above, even after 120 minutes. Low doses of HU (500 mg/kg) produced only ACV dilations in some embryos by 30 minutes. Histologic analysis of HU embryos confirmed the in vivo microscopic observations. The drastic CV derangements exhibited by many embryos may be one of the causes for the high resorption rates associated with the treatment. Furthermore, since teratogenic doses of HU produce immediate hemorrhages and hematomas in the embryos in the same craniofacial areas which are later deformed in the term fetus, it is possible that the teratogenic action of this drug may be related to the initial vascular embryopathies.
Differential embryonic cardiovascular responses to acute maternal uterine ischemia: An in vivo microscopic study of rabbit embryos with either intact or clamped umbilical cords
Authors: Millicovsky Guillermo , DeSesso John M.
Published: June 2005

The effects of acute episodes of maternal uterine ischemia on the cardiovascular system of New Zealand white rabbit embryos were studied by in vivo microscopic methods. On gestational day 12, gravid uteri were surgically externalized, and the walls of the implantation sites were carefully incised and reflected to reveal the embryos. Throughout all procedures, temperature, water, and electrolyte homeostasis were preserved. The embryos within each litter were divided into two groups: 1) two randomly selected embryos whose umbilical cords were clamped, and 2) the remaining embryos of the litter whose umbilical cords were uncompromised. Uterine ischemia was induced by clamping all uterine arterial and venous channels. Occlusion of the maternal uterine vessels produced severe uterine cyanosis within 1–2 min. The embryos whose umbilical cords were not clamped exhibited severe cardiovascular derangements beginning within 3–4 min. In contrast, the embryos whose umbilical cords were clamped (thereby interrupting both umbilical and vitelline circulations) had no observable cardiovascular alterations. The absence of effects in embryos with clamped umbilical cords suggests that acute episodes of hypoxia are well tolerated by young embryos. In contrast, the rapid appearance of cardiovascular derangements after interruption of maternal uterine circulation in embryos with undamped umbilical cords emphasizes the idea that even brief intervals of uterine ischemia are deleterious to the rabbit embryo.
Investigations on cyclophosphamide treatment during the preimplantation period. II. In vitro studies on the effects of cyclophosphamide and its metabolites 4‐OH‐cyclophosphamide, phosphoramide mustard, and acrolein on blastulation of four‐cell and eight‐cell mouse embryos and on their subsequent development during implantation
Authors: Spielmann Horst , Jacob‐müller Ursula
Published: June 2005

Preimplantation mouse embryos were cultured for 48 hours from the four‐cell and eight‐cell stage to the blastocyst stage in the presence of Cyclophosphamide (CPA) or one of its metabolites–4‐hydroperoxy‐CPA (4‐HP‐CPA), phosphoramide mustard (PAM), and acrolein (Acr)‐to identify the metabolite which is embryotoxic after CPA treatment of pregnant mice during the preimplantation period. The dose‐response relations for the inhibition of blas‐tulation revealed identical inhibition curves for PAM and 4‐HP‐CPA (in solution 4‐HP‐CPA immediately decomposes to 4‐hydroxy‐CPA (4‐OH‐CPA)). These two metabolites are inhibiting blastulation in vitro at concentrations that are 10,000 times lower than CPA and 100 times lower than acrolein. When blastocysts which had developed in the presence of CPA and its metabolites in vitro were subsequently cultured in inhibitor‐free medium NCTC‐109, the same dose‐response relationship pattern was obtained. Since 4‐OH‐CPA decomposes into acrolein and PAM in vivo and in vitro and since PAM and 4‐OH‐CPA exhibit identical embryotoxicity towards preimplantation embryos in vitro, PAM probably also is an active embryotoxic CPA metabolite in vivo before implantation. This result is discussed in relation to the importance of alkylating CPA metab‐olites in cancer treatment and in teratological studies during organogenesis.
Teratogenesis of retinoic acid in rats: Susceptible stages and suppression of retinoic acid‐induced limb malformations by cycloheximide
Authors: Kistler Andreas
Published: June 2005

The susceptible stages and the malformation pattern produced by excess retinoic acid were investigated in rat fetuses. Retinoic acid (120 mg/kg body weight, suspended in rape oil) was administered orally to pregnant females on one of the first 20 days of gestation. Fetuses were examined for external and, after visualization of the skeleton with alizarin red, for skeletal malformations on the 21st day of gestation. Retinoic acid was highly embryolethal when administered on days 9 and 10 of gestation (96.2 and 100% resorptions). The earliest teratogenic effect of retinoic acid was noted on the 9th day of gestation. Severe multiple defects were produced by retinoic acid administration on days 9 and 11 of gestation, but more specific malformations involving the axial skeleton, the fore‐ and hindlimbs, and cleft palate resulted from treatment on days 12–18 of gestation.

Cycloheximide, an inhibitor of protein synthesis, reduced the incidence of limb defects induced by retinoic acid. This result indicates that the teratogenic effect of retinoic acid on limb morphogenesis may be dependent upon continuous protein synthesis and is compatible with the view that vitamin A may act like a hormone.
Prevention of congenital malformations
Authors: Warkany Josef
Published: June 2005

Prevention of congenital malformations is recognized as the ultimate goal of teratology, a goal that has not yet been reached despite much progress in the description, experimental production, and treatment of birth defects. In addition to quests for the causes of congenital malformations and the removal of these causes, indirect preventive methods must be sought that could aid in eliminating these malformations as sources of children's morbidity and mortality.
Neuromuscular blocking agents and axial teratogenesis in the avian embryo. Can axial morphogenetic disorders be explained by pharmacological action upon muscle tissue?
Authors: Meiniel Robert
Published: June 2005

A comparative qualitative and quantitative study of the embryotoxic and teratogenic activities of various chemical agents known to have neuromuscular blocking properties was done on the quail embryo. Intrinsic embryotoxic activity and teratogenicity were evaluated for each agent, and the qualitative nature of the teratogenic effects was correlated with the pharmacologic properties of the different effectors. Gross malformations (contorted posture) were found only with agents which directly (cholinergic agonists) or indirectly (cholinesterase inhibitors) favor muscle membrane depolarization, suggesting that such malformations may be due to muscle contraction following depolarization. All of the agents studied produced variable degrees of vertebral fusion, apparently due to paralysis resulting either from sustained depolarization (cholinesterase inhibitors and cholinergic agonists) or directly from cholinergic blockade (cholinergic antagonists and neurotoxins).
Teratogenic effect of lambda‐carrageenan on the chick embryo
Authors: Monis Benito , Rovasio Roberto A.
Published: June 2005

Carrageenans are widely used as food additives. Thus, it seemed of interest to test their possible teratogenic action. For this purpose, 530 chick eggs were injected in the yolk sac with 0.1 ml of a solution of 0.1% lambda‐carra‐geenan in 0.9% sodium chloride. As controls, 286 eggs were injected with 0.1 ml of 9.0% sodium chloride. In addition, 284 eggs received no treatment. After incubation for 48–50 hours at 39°C, embryos were fixed, cleared, and observed with a stereoscopic microscope.

The frequency of abnormal embryos in the group receiving lambda‐carrageenan was higher than in the controls (p<0.04). Partial duplication of the body, abnormal flexures of the trunk, anencephaly, a severely malformed brain, thickening of the neural tube wall, an irregular neural tube lumen with segmentary occlusion and a reduction in crown‐rump length and number of somites were distinctly seen in the lambda‐carrageenan‐injected group. Moreover, the average number of anomalies per embryo in the lambda‐carrageenan‐injected group was nearly twice that in the controls. Present data indicate that lambda‐carrageenan has teratogenic effects on early stages of the development of the chick embryo.
Pathogenesis of bromodeoxyuridine‐induced polydactyly
Authors: Scott William J.
Published: June 2005

Intraperitoneal injection of BUdR on day 11 or 12 of rat gestation produced preaxial polydactyly of the hindlimb. The pathogenesis of this deformity differed from that of other polydactyly regimes in that drug‐induced mesenchymal necrosis was not an essential feature. Likewise an altered pattern of physiological necrosis in the apical ectodermal ridge (AER) was not evident in hindlimbs of BUdR‐treated embryos. In keeping with earlier studies, a zone of physiological necrosis within the preaxial mesoderm thought to be instrumental in controlling preaxial digitation was abolished. Speculation has focused on the incorporation of BUdR into these prospectively necrotic cells as the means by which they survive. Support for this idea is gained from the protective effect of concomitant thymidine administration, which presumably prevents BUdR incorporation.
Vascular hypervolemia and hematoma formation in chick embryos treated with trypan blue
Authors: Weaver T. E. , Kaplan S. , Rajala G. M.
Published: June 2005

The relationship between cardiovascular disturbances and the formation of hematomas in trypan blue‐treated chick embryos was investigated. Hematocrits from Hamburger‐Hamilton stage 15 and 16 embryos (8–10 hours after treatment at stage 13) were obtained. The hematocrit value from the treated embryos was significantly lower (P < 0.001) than the values from controls. Unopened and saline‐injected control values were not significantly different (P > 0.05). We interpret this to mean that there is excess circulating fluid volume in the treated embryos. The results of direct injection of measured volumes of fluid into the cardiovascular system of normally developing embryos (stages 15 and 16) provided evidence to suggest that the caudal dorsal aortae are susceptible to fluid‐induced distension and rupture.
Modification of the mutagenicity and teratogenicity of cyclophosphamide in rats with inducers of the cytochromes P‐450
Authors: Hales Barbara F.
Published: June 2005

Cyclophosphamide must be enzymatically activated to be either mutagenic or teratogenic. This activation is thought to be catalyzed by the cytochrome P‐450 monooxygenase system. To study the relationship between the mutagenic and teratogenic metabolites of Cyclophosphamide, the mutagenicity and teratogenicity of this drug were compared after activation by rats pretreated with chemicals (phenobarbital and β‐naphthoflavone) inducing different cytochromes P‐450. Activation of Cyclophosphamide to mutagenic metabolites by enzyme fractions from rats on day 13 of gestation was measured with the Ames test using Salmonella typhimurium TA1535. Teratogenicity was assessed in vivo by treatment of rats with Cyclophosphamide on day 13 of gestation. Cyclophosphamide was activated to mutagenic metabolites to the same extent (on a tissue wet weight basis) by enzyme fractions from maternal liver, kidney and placenta, despite differences in cytochrome P‐450 content. Fetal homogenates did not activate Cyclophosphamide. Phenobarbital pretreatment increased the activation of Cyclophosphamide to mutagenic metabolites by maternal liver microsomes 10‐fold and liver cytochrome P‐450 content 1.8 fold; however, this drug did not alter the activation of Cyclophosphamide by maternal kidney, by placenta or by the fetus. Phenobarbital pretreatment increased the teratogenicity of cyclophosphamide in rats on day 13 of gestation (increased incidence of malformed embryos, decreased fetal weight). Pretreatment with β‐naphthoflavone did not induce liver cytochrome P‐450 in the pregnant rat and did not change the activation of cyclophosphamide to mutagenic metabolites by liver, kidney, placenta or the fetus. Pretreatment with this polycyclic aromatic hydrocarbon had no effect or decreased the teratogenicity of cyclophosphamide. Thus, these experiments suggest that the mother, rather than the fetus, is the site of activation of cyclophosphamide; after phenobarbital pretreatment the predominant site of cyclophosphamide activation is the maternal liver. There appears to be a correlation between the teratogenicity and mutagenicity of cyclophosphamide after induction of the cytochromes P‐450. We can speculate that the “proximate teratogen” of cyclophosphamide may also be the “proximate mutagen”.
Immunohistochemical localization of cyclic AMP during normal and abnormal chick and mouse limb development
Authors: Elmer William A. , Smith Mary Alice , Ede Donald A.
Published: June 2005

This paper describes the immunohistochemical localization of cAMP during limb chondrogenesis in talpid3 chick, brachypod mouse, and normal embryos. Comparisons were made between chick wing buds at Stages 22, 25, and 30, and mouse hind limb buds at Days 11, 12.5, and 14. At Stage 22, the normal mesenchyme in the chick displayed areas of bright fluorescence compared to a lesser intense and more evenly distributed fluorescence in talpid3. Sections of the central region from normal Stage 25 limb buds exhibited an intense fluorescence that was uniformly distributed, whereas, in talpid3 staining was more, mosaic with some areas fluorescing brightly and others showing little fluorescence. At Stage 30 the staining pattern was similar between normal and talpid3, with the fluorescence being brighter in the cartilage tissue than in the surrounding soft tissue. Differences in the staining patterns of normal and brachypod limb tissue were not detectable. At Days 11 and 12.5, tissue from both genotypes displayed a very bright, uniform fluorescence. In the 14‐day hind limb buds, the staining patterns were comparable to those observed in Stage 30 chick wing buds. However, under in vitro conditions conducive for the expression of the chondrogenic phenotype, differences in the intensity and extensiveness of fluorescent staining were detectable in cultures derived from 12‐day normal and brachypod hind limb mesenchyme. Compared to the control, the uneven distribution of immunofluorescence in the talpid3 limb buds and the differences in intensity and extensiveness of fluorescence in the brachypod cultures support the hypothesis that cAMP is involved in limb cartilage differentiation.
Placental findings in spontaneous abortions and stillbirths
Authors: Ornoy A. , Salamon‐Arnon J. , Ben‐Zur Z. , Kohn G.
Published: June 2005

Placentae and membranes of 360 spontaneous abortions and stillbirths were studied by light microscopy and compared to 100 induced abortions of 2–5 months gestation. The placental findings were correlated with morphological and chromosomal studies of the fetuses. A high incidence of hydatid degeneration was found in early spontaneous abortions (less than 12 weeks of age), especially in “blighted ova.” “Atypical” stromal cells were found in the placental villi of early abortions with trisomy and triploidy. In late spontaneous abortions (13–18 gestational weeks) inflammatory lesions of the placentae were observed in over a third of cases and the incidence of hydatid degeneration was very low. The incidence of inflammatory lesions of the placentae was further raised in cases of early fetal death (18–24 gestational weeks), involving 60% of the placentae of fetuses without malformations. In stillborn infants, over 25 weeks of age, the incidence of inflammatory placental lesions dropped again, and the incidence of vascular lesions was raised to 50%. It seems that inflammatory lesions of the placentae may play an important role in the etiology of midtrimester spontaneous abortions. Isolation of the infectious microorganism and subsequent treatment may therefore reduce the rate of fetal losses in this group.