Craniofacial abnormalities induced by retinoic acid: a preliminary histological and scanning electron microscopic (SEM) study

Exogenous retinoic acid has been found to be teratogenic in animals and man. Craniofacial defects induced by retinoic acid have stimulated considerable research interest. The present report deals with scanning electron microscopical observations of the craniofacial region concurrent with histological examination of craniofacial dysmorphism induced in rat embryos following maternal treatment treated with varying dosages of all-trans-retinoic acid (tretinoin). Two groups of pregnant rats were treated with rat embryos exposed to retinoic acid suspended in corn oil (100 mg/kg b.w. on gestational day 11.5 and 50 mg/kg b.w. on gestational day 10, 11 and 12 respectively). A third group was treated with corn oil (vehicle) while a fourth group remained untreated. A wide spectrum of congenital abnormalities, including exophthalmos, microphthalmia and anophthalmia, maxillo-mandibular dysostosis, micrognathia of both maxilla and mandible, cleft palate, subdevelopment of ear lobe, preauricular tags and macroglossia, were observed in the offspring of retinoic acid treated animals. The abnormalities were both time and dosage dependent, and characteristic of Treacher Collins syndrome when retinoic-acid was administered on gestational day 11.5. In contrast, when retinoic acid was administered were on gestational days 10-12, the defects were similar to those seen in the first and second pharyngeal arch syndrome, as well as in the oculo-auriculo-vertebral spectrum. Whereas our data support the hypothesis that all-trans retinoic-acid disturbs growth and differentiation of several embryonic cell types essential for normal craniofacial development, its mechanism of action remains unclear.

Histological observations of palatal malformations in rat embryos induced by retinoic acid treatment

Malformations of the palate were induced in white rat embryos following maternal exposure to retinoic acid (tretinoin). Five experimental groups and the controls were treated by the following protocol: Group 1: pregnant rats received 100 mg retinoic acid (RA)/kg b.w. suspended in corn oil on gestational day (GD) 11.5; Group 2: 20 mg RA/kg b.w. from GD 8-12; Group 3: 20 mg RA/kg b.w. from GD 7.5-11.5; Group 4: 100 mg RA/kg b.w. on GD 10-11; Group 5: 100 mg RA/kg b.w. on GD 10 and 12; Group 6 received corn oil vehicle from GD 7-14.5; and Group 6: served as non-injected controls. In all retinoic acid treated groups, varying degrees of clefts with occasional attempts of fusion were noted. The severity and frequency of the malformations were dependent on dosage or gestational day of drug treatment. Our results indicate that RA, even at the lowest dose tested (20 mg/kg b.w.) severely affects the various tissues constituting the embryonic palatal shelves by altering cell interaction and possibly programmed cell death. These events would then result in lack of or inadequate differentiation with subsequent formation of aberrant craniofacial architecture.

Influence of rat placental lactogen-I on the development of whole rat embryos in culture

Rat placental lactogen-I (rPL-I), the first prolactin-like hormone expressed in the placenta during pregnancy in the rat, is known to influence maternal functions. In the present study, we have investigated the effects of rPL-I on the growth and development of cultured whole rat embryos. Rat embryos, with or without ectoplacental cone (EPC) attached, were explanted at day 9 of gestation. After 48 h of culture, the embryos, enclosed by the yolk sacs, were assessed by the presence of visible heart contractions ('heart beats'), crown-rump length (CRL) and yolk sac diameter (YSD). When intact embryos with EPC were cultured, the concentrations of rPL-I and rPL-II (products of EPC) in the medium were 850+/-841 and 92+/-181 ng/ml respectively (means+/-s.e.m.). In embryo cultures with the EPC removed, rPL-I levels decreased to</=10 ng/ml, and only 70% of the embryos were viable, with visible heart beats. In the viable embryos, both CRL and embryonic DNA synthesis were reduced compared with controls, and the addition of rPL-I (1 microg/ml) did not prevent this reduction. YSD and yolk sac DNA synthesis were also reduced compared with control embryos, and the addition of rPL-I significantly prevented this decrease by 45%. In embryos cultured without EPC in the presence of neutralizing rabbit anti-rat prolactin serum (anti-rPRL), embryonic and yolk sac DNA synthesis were reduced by 35% compared with embryos exposed to normal rabbit serum. Addition of rPL-I significantly increased (P<0.05) embryonic and yolk sac growth. Thus the effects of rPL-I on embryo growth could only be seen in the absence of prolactin. The addition of human prolactin in the presence of anti-rPRL also resulted in significant increases (P<0.05) in embryonic DNA synthesis and CRL. These results suggest that rPL-I may substitute for prolactin to influence the growth of the rat embryo.

Ethanol effects on postimplantation rat embryos: influence of zinc and methionine

Organic zinc salts and thiols, administered simultaneously, protect mice synergistically against ethanol toxicity. Moreover, chronic ethanol consumption could affect the bioavailability of zinc and amino acids such as methionine. This could result in impaired embryonic growth and development. The influence of zinc and methionine on ethanol-induced embryopathy was investigated by simultaneous administration of ethanol, zinc and methionine to pregnant rats from gestational day 6 through 12. Ethanol was given in the form of a liquid diet; zinc administered i.p., and methionine was given by gavage. The ethanol group received the liquid ethanol diet; the ethanol + zinc and methionine group received the ethanol diet, zinc and methionine; and the pair-fed control group was given an isocaloric control diet. On day 12 of gestation, embryos of ethanol alone treated rats revealed a significantly reduced embryonic protein content, number of somites, crown-rump length, and lower morphological score (embryological differentiation) compared to the pair-fed control embryos. However, embryonic growth and developmental parameters in the ethanol, zinc and methionine treated group were not significantly different from those exposed to ethanol alone.

Biotin influences palatal development of mouse embryos in organ culture

Maternal biotin deficiency is strongly teratogenic in CD-1 mice. The most common malformations are craniofacial and limb defects such as cleft palate, micrognathia and micromelia. The effect of biotin deficiency on palatal development in mouse embryos on d 12 of gestation was studied by culturing mouse embryonic palates in serum-free medium using a suspension culture system. In control embryos palatal processes developed to the fused stage after 72 h in culture. The fusion of palatal processes was further increased by the addition of biotin (10(-8) mol/L) to the medium. The addition of organic acids such as propionic, beta-methyl crotonic or beta-hydroxy isovaleric acids as well as avidin to the medium did not affect the stage of palatal formation. Cycloheximide completely blocked the fusion of palatal shelves. In embryos from biotin-deficient mice, the incidence of fusion between the palatal shelves was < 7% and increased to > 30% when biotin (10(-8)-10(-6) mol/L) was added to the medium. The addition of fatty acids to the organ culture medium did not have any effect on the fusion of palatal processes. The incorporation of 35S-methionine into protein from biotin-deficient embryo explants was 88% of that in controls. The results indicate that biotin deficiency may interfere directly with synthesis of specific proteins and the formation of palatal processes.

Effects of prenatal exposure to low dose ionizing radiation on the development of the cerebellar cortex in the rat

The effects of maternal exposure to a single dose of whole body irradiation (0.5 Gy) on gestational days (GD) 17, 18, 19, or 20 on the development of the cerebellar cortex was examined in the offspring of Sprague Dawley rats at 21 and 28 days postnatally. No gross cerebellar anomalies were observed in the irradiated animals. However, compared to control animals, rat irradiated on each of GD-17, 18, 19 and 20 showed a significantly higher incidence (p < 0.05) of circumscribed cerebellar lesions (CL) distributed in the inner granular layer of the anterior and posterior lobes. These lesions were characterized by a loss of granule cells and atrophied and/or reduced number of Purkinje cells. In 21 days old rats, irradiation on GD-17 resulted in more CL anteriorly (75%) and in the vermis whereas on GD-20, the CL predominated posteriorly (100%) and in the lateral hemispheres. In 28 day old rats, following irradiation on each of GD-17 and GD-20, there was an equal distribution of CL in both the anterior and posterior lobes. However, with irradiation on both GD-17 and GD-20, these CL occurred more frequently in the lateral hemispheres of the anterior lobe, whereas in the posterior lobe they predominated in the vermis. These results suggest that a direct relationship exists between the proliferation, migration, development, and maturation of granule cells and their induction by Purkinje cells. The findings also support the view that both cell death and the regulation of granule cells by Purkinje cells maximize the effective development and organization of the cerebellum.

Influence of zinc on ethanol-induced placental changes in the rat

For normal fetal growth and development, an ample supply of nutrients and oxygen is essential. The placenta is the conduit for nutrient transfer and thus any factor that alters normal placental structure and function may adversely affect the nutritional status of the fetus. The effect of ethanol ingestion and zinc supplementation on placental structure was investigated by the simultaneous administration of ethanol and zinc to pregnant Sprague-Dawley rats from gestational day 6 through 12. One group of animals was given an ethanol liquid diet, a second group received the ethanol liquid diet plus zinc, and another group was pair-fed a control liquid diet. Placentas were recovered on day 20 of gestation. The mean placental weight in the ethanol group was significantly higher than that in either the pair-fed control or the ethanol plus zinc group. The ethanol-treated group revealed more stagnated blood in the basal-decidual and in the basal-labyrinthine junctions. Intervillous spaces in the labyrinthine zones were markedly dilated and filled with more blood corpuscles compared to the pair-fed control group. The giant cells of the basal zone were also larger in size in the ethanol-treated group. The frequency of occurrence of stagnated blood in either the labyrinthine zone and in the basal-labyrinthine junction was less in the ethanol plus zinc group compared to the ethanol group.

Protective influence of zinc against the deleterious effects of ethanol in postimplantation rat embryos in vivo

Zinc is a cofactor for alcohol dehydrogenase, the ethanol metabolizing enzyme. Ethanol-induced zinc deficiency could decrease ethanol metabolism, resulting in an increase in circulating and tissue ethanol levels. This may cause retardation in embryonic growth and development. The influence of zinc supplementation on ethanol-induced embryopathy was studied by the simultaneous administration of ethanol and zinc to pregnant SD rats from gestational day 6 through 12. Ethanol was given in the form of a liquid diet and zinc was administered intraperitoneally. The ethanol group received the liquid ethanol diet, the ethanol+zinc group received the ethanol diet and zinc and the pair-fed control group was given an isocaloric control diet. Embryos were explanted from all groups on day 12 of gestation. Embryos of animals treated with ethanol alone exhibited a significantly higher rate of resorption and retarded embryonic growth and development compared to the pair-fed control group. The embryonic protein content, crown-rump length, the number of somites and embryonic morphological score were significantly reduced in the ethanol-treated group. In addition, serum zinc concentration also was lower. Compared to embryos from ethanol-treated animals, embryos from ethanol+zinc treated animals showed a significantly higher number of somites; cardiac development was more advanced and embryonic protein content was higher. These observations suggest that zinc supplementation of ethanol-treated pregnant rats may have some protective influence against the embryopathic effects of ethanol.

Purkinje and granule cells distribution in the cerebellum of the rat following prenatal exposure to low dose ionizing radiation

The effects of maternal exposure to a single dose of whole body irradiation (0.5 Gy) on gestational days (GD) 17, 18, 19, or 20 on the number of Purkinje and granule cells in the pyramis of the cerebellar cortex was examined in the offspring of Sprague Dawley rats at 21 and 28 days postnatally. The laterolateral distribution of both granule and Purkinje cells in the pyramis were significantly reduced (p < 0.001) from controls in rats irradiated on each of GD-17, 18, 19 and 20. There was a greater deficit in granule cell number with irradiation on GD-20 than on GD17 (p < 0.05). Purkinje cells were reduced in number with irradiation on GD-17 and GD-20; however, the decrease did not correspond to the degree of reduction in the number of granule cells. There was a greater reduction of both granule and Purkinje cells in the vermis with irradiation on GD-17, whereas on GD-20, both granule (p < 0.05) and Purkinje cells (p < 0.001) were more reduced in the lateral hemispheres. The GC/PC ratio was smaller in rats irradiated on GD-20 than on GD-17. The GC/PC ratio between the irradiated animals and the controls were relatively similar. The findings show that irradiation does not affect the population of granule cells directly, but rather indirectly. The reduction in the number of granule cells could be an indirect consequence of reduced critical interaction with Purkinje cells. These results suggest that a direct relationship exists between the proliferation, migration, development, and maturation of granule cells and their induction by Purkinje cells.

In vitro effect of S-adenosyl methionine on ethanol embryopathy in the rat

S-adenosyl methionine (SAM) is a universal methyl donor for biological systems. Chronic consumption of ethanol results in depletion of available SAM and reduces its biosynthesis in the transmethylation pathway. Administration of excess SAM may reduce the embryopathic effects of ethanol. The in-vitro effects of SAM on ethanol embryopathy was investigated by culturing 9.5 day old whole rat embryos for 48 hours in ethanol alone (Group II), 0.05 mM SAM (Group III), ethanol + 0.05 mM SAM (Group IV), ethanol + 0.1 mM SAM (Group V), ethanol + 1 mM SAM (Group VI), and in ethanol + 3 mM SAM (Group VII). In Group VII embryos, cardiovascular, nervous, auditory, visual, craniofacial and musculoskeletal systems were retarded in development; crown-rump length, yolk-sac diameter, as well as morphological scores, were reduced compared to those in embryos treated with ethanol alone (Group II). There were, however, significant differences between Group II and Group IV embryos with respect to crown-rump length, yolk sac diameter and somite number. The mean crown-rump length, yolk sac diameter and somite number in Group II were 2.3 +/- 0.2, 2.8 +/- 0.3 and 22.4 +/- 3.5 respectively, compared to 2.6 +/- 0.2, 3.1 +/- 0.2 and 25.3 +/- 3.1 in Group IV. These results suggest that simultaneous administration of S-adenosyl methionine and ethanol may protect against the embryopathic effects of ethanol.

Effects of in utero exposure to low dose ionizing radiation on development in the rat

Most studies of in utero effects of ionizing irradiation involve high doses and examination at postnatal intervals. Little information is available on the effects of low levels of ionizing radiation on embryogenesis. The developmental effects of in utero exposure to 50 cGy gamma radiation on gestational day-9.5 was investigated using Sprague-Dawley rats. Irradiated rats and appropriate controls were killed at prenatal intervals of 4h, 48h and 10 days after exposure. Fetuses were examined for abnormalities and random samples of tissues were prepared for microscopic study. With the exception of the neuroepithelium, no histopathological changes were observed in embryos 4h after exposure to 50 cGy. In irradiated embryos, mitoses were reduced within the neuro-epithelium; pyknosis and some necrosis of cells were apparent at this gestational interval. Among the gross developmental abnormalities observed in embryos 48h after irradiation, excessive flexion of the embryo and abnormal flexion of the head were the only ones that appeared to be radiation-induced. The mean numerical score (42.3 +/- 0.2, controls; 42.4 +/- 0.1, irradiated) for 17 morphological parameters examined in fetuses at this gestational period compares favorably with other studies. Controls, however, showed greater variability in the extent of development of their forebrain, olfactory system, midbrain, hindbrain, and caudal neural tube. In all cases, there was evidence of slower development in these regions compared to their irradiated counterparts. At term, no significant differences in litter size or resorption rates were observed in irradiated animals compared to the controls, but there was a higher incidence of defective eye development, spinal curvature and visceral anomalies.(ABSTRACT TRUNCATED AT 250 WORDS)

Postnatal development of the rat CNS following in utero exposure to a low dose of ionizing radiation

In utero exposure to ionizing radiation is of importance because of its potential health risks. The developing nervous system is particularly vulnerable and the consequences of exposure to low levels of radiation (< or = 1 Gy) are not well established. The developmental effects of maternal exposure to 50 cGy gamma-radiation on gestational days (GD) 9.5, 15, and 18 were investigated in Sprague Dawley rats. Rats exposed on GD-9.5 along with appropriate controls were killed at 4 h, 48 h, and 10 days post-irradiation while those irradiated on GD-15 and GD-18 were killed postnatally (PN) on days 7 and 26. All were examined for developmental anomalies and representative samples of brains were processed for microscopic study. No significant developmental differences were observed between irradiated and control embryos killed 48 h after irradiation on GD 9.5. However, in irradiated fetuses a larger number of developmental anomalies were observed at term. Defects of the eye and of spinal curvature were the most common malformations encountered. Mitoses were reduced within the neuroepithelium of embryos irradiated on GD-9.5 and evidence of pyknosis and necrosis was seen 4 h after irradiation. The capacity of surviving primitive neural cells for repair, however, was such that by 48 h after exposure the irradiated nervous system no longer differed from controls. Rats irradiated on GD-15 and GD-18 and examined on PN-26 exhibited clusters of small, dark, pyknotic neurons within the hippocampal and dentate gyri, often bilaterally.(ABSTRACT TRUNCATED AT 250 WORDS)

Ossification of the vertebral column in the offspring of rats exposed to alcohol, acetaldehyde and caffeine

The embryopathic effects of alcohol have been widely studied in humans and laboratory animals. However, the role of risk factors remains largely unknown. Whereas skeletal abnormalities are often present in the offspring of alcoholic mothers, these have not been fully documented. This report is concerned specifically with the development of the vertebral column in rats exposed in utero to ethanol, its primary metabolite acetaldehyde, and caffeine. Our results indicate a possible causal association between alcohol abuse and ossification anomalies of the vertebral column. Maternal treatment with caffeine accelerated ossification in the sacro-caudal vertebrae. Caffeine combined with ethanol only moderately affected the development of the centra and arches.

Embryonic development in the chick following exposure to ethanol, acetaldehyde and cyanamide

The influence of cyanamide, an inhibitor of aldehyde dehydrogenase, on the embryopathic effects of ethanol and acetaldehyde, was investigated in the chick embryo. Both ethanol and cyanamide significantly increased embryonic mortality, but did not affect embryonic growth, compared to treatment with either ethanol or cyanamide. Acetaldehyde combined with cyanamide increased embryonic mortality and retarded embryonic growth. Cyanamide influence on embryonic development was minimal. The extent of acetaldehyde involvement in ethanol teratogenicity remains unclear from the present findings.

Prenatal influence of alcohol following a single exposure in two inbred strains of mice

The effect of a single dose of ethanol on embryonic development was investigated in two inbred strains of mice. Ethanol (25% v/v solution, 0.02 ml/g body weight) was administered intraperitoneally on either gestational day 6, 9 or 12 to C57BL/6J and DBA/2J mice. All fetuses recovered near term were alive and appeared normal. The incidence of fetal death was not affected. Fetal weight was significantly reduced in the C57BL/6J strain of mice. Maternal exposure to a single and moderate dose of ethanol did not have any profound effect on the conceptus. For the development of laboratory models to mimic fetal alcohol effects in humans, the selection of appropriate genotype is important.

New familial syndrome of unilateral upper eyelid coloboma, aberrant anterior hairline pattern, and anal anomalies in Manitoba Indians

We report on 6 (3 male, 3 female) Manitoba Indian children with hypertelorism and variable combinations of unilateral eye malformations, aberrant anterolateral scalp hairline, and nasal and anal anomalies. These children belong to 4 related families. The parents and 7 other sibs are clinically unaffected. The family histories are otherwise unremarkable. The presence of 2 major malformations in sibs and related individuals (with unaffected parents) suggests that this is a newly described pleiotropic autosomal recessive syndrome. The differential diagnosis includes cryptophthalmos syndrome and several other related malformation syndromes. Although multifactorial determination cannot be excluded, the inbred, isolated population and distribution make autosomal recessive inheritance more likely.

Effects of alcohol and caffeine on cultured whole rat embryos

The direct effects of ethanol and caffeine on embryogenesis were investigated using the whole rat embryo culture system. Compared to control embryos, the crown-rump length, number of somites, branchial bars, and morphological score were significantly reduced in embryos exposed to ethanol, caffeine, or both substances. Development of the craniofacial region, cardiac primordium and forelimb was delayed following ethanol treatment. Compared to the controls, the anterior neuropore lagged in development following caffeine treatment; closure of the posterior neuropore was significantly delayed in each of the treatment groups. The optic and olfactory primordia were not affected. The results indicate that alcohol and caffeine independently affect the embryo, but when combined their effects were not potentiated.

Can methionine and zinc prevent the embryopathic effects of alcohol?

Alcoholism is a major and world-wide health problem. A characteristic pattern of congenital defects, known as the fetal alcohol syndrome, has been detected in the offspring of mothers who are chronic alcoholics. The mechanism underlying the teratogenic effects of ethanol is not known. An important hypothesis is that ethanol becomes teratogenic by inducing maternal/fetal nutritional deficiencies. Nutrients affected by ethanol consumption include methionine and zinc. Epidemiological and experimental studies have shown that zinc deficiency is associated with both fetal growth retardation and developmental defects. Furthermore, the ethanol metabolizing enzyme, alcohol dehydrogenase, is a zinc metalloenzyme. Zinc deficiency decreases alcohol dehydrogenase activity and thus slows down elimination of ethanol. Methionine, an essential amino acid, is a lipotrope, as well as a universal methyl donor. It is involved in hepatic detoxification. Studies on the effects of methionine and zinc might lead to appropriate therapeutic intervention in pregnancies of alcoholic mothers who are at a risk of giving birth to an impaired offspring. Furthermore, the results of such investigations will provide a better understanding of the mechanism of action of ethanol on the embryo.

Influence of 13-cis and all-trans retinoic acid on rat embryonic development in vitro: correlation with isomerisation and drug transfer to the embryo

In vitro experiments using whole rat embryo cultures show that all-trans retinoic acid (all-trans RA) administered at low concentrations (30 ng/ml culture medium) is 10 times more active than 13-cis retinoic acid (13-cis RA) and 3 times more active when administered at high concentrations (1000 ng/ml culture medium). Morphological investigation of the embryos shows that both substances directly influence embryonic development in an identical manner. Isomerisation products of the administered compounds (all-trans RA from 13-cis RA and vice versa) were detected by HPLC both in the culture medium and the embryo. Correlation of embryonic retinoid concentration with the observed effects led us to suggest that the isomerisation to all-trans RA is crucial in regard to 13-cis RA-induced abnormal embryonic development. A 100% effect can be induced in vitro with very low amounts of all-trans RA (7.2 ng/g) in the embryo.

Maternal and fetal chromosomal aberrations in mice following prenatal exposure to subembryotoxic doses of lead nitrate

Maternal exposure to low levels of lead nitrate (12.5, 25, 50 mg/kg body weight), administered on the 9th day of gestation, did not cause embryonic resorption and fetal lethality, but induced chromosomal deletions and other forms of aberrations in fetal liver and maternal bone marrow cells.

Embryotoxicity and in vivo cytogenetic changes following maternal exposure to cadmium chloride in mice

Cadmium is a well-known teratogen in laboratory animals and a widespread environmental pollutant. The frequencies of sister chromatid exchanges (SCEs), nucleolar organizing regions (NORs) and chromosomal aberrations were analysed in maternal bone marrow and fetal liver and/or lung cells of mice, following maternal treatment with cadmium chloride, on gestational days 8 through 10. The embryotoxic effects and morphological changes on day 18 fetuses were also studied. Cadmium chloride is readily transferred across the placenta and significant levels were detected in both the placenta and fetus. No significant changes in the frequencies of SCEs or NORs in maternal and fetal cells were observed following exposure to cadmium chloride. Fetal tissues showed mitotic inhibition at the highest dose levels (8.4 and 11.4 mg/kg, b.w.). Maternal treatment with cadmium chloride increased embryonic resorptions and fetal lethality, as well as reduced placental weight; however, it did not produce significant chromosomal changes except at the highest dose level (11.4 mg/kg).

Historical development of the concept of a pulmonary circulation

Philosophical speculations and theories regarding the flow of blood through the lungs are reviewed from an historical standpoint. Michael Servetus (1511-1553) described the pulmonary circulation in his book 'Christianismi Restitutio', published in 1553. From manuscripts that were rediscovered and translated in 1924 we now know that Ibn al-Nafis (1210-1288) of Damascus had made the same observations three centuries earlier.

Relationship of embryotoxicity to genotoxicity of lead nitrate in mice

Frequency of sister chromatid exchanges (SCEs), nucleolar organizing regions (NORs) and chromosomal aberrations were analysed, in maternal bone marrow and fetal liver and/or lung cells of ICR Swiss Webster mice, following maternal exposure to lead nitrate on gestational day 9. The number of implantations and morphological changes in day 18 fetuses, following the treatment, were also noted. Chemical analysis of lead in maternal and fetal tissues showed that it is readily transferred across the placenta. Lead caused a moderate, but statistically significant, increase in the frequency of SCEs in maternal bone marrow cells and significant reduction in NORs at the 2 highest dose levels (150 and 200 mg/kg b.w.). Lead treated animals showed several specific chromosomal aberrations, mostly deletions in maternal bone marrow and fetal cells. Aneuploidy was found to be frequently associated with the lowest dose levels of lead nitrate (100 mg/kg). Maternal treatment with lead nitrate also significantly increased embryonic resorptions and reduced placental weights. The results suggest that the embryotoxic effects of lead might be associated with the chromosomal changes.

Influence of nicotine and caffeine on rat embryonic development

The influence on embryonic development of nicotine and caffeine at dose levels approximating human consumption was investigated in Sprague-Dawley rats. One group of animals received nicotine administered subcutaneously by an Alzet mini-osmotic pump from gestational day 6 through 12 (25 mg over 7 days; rate 149 micrograms/hr). Control animals received physiological saline in a similar manner. A second group received a single intravenous injection of caffeine (25 mg/kg) on gestational day 6. Control animals were treated with physiological saline. A further group received both nicotine and caffeine on gestational day 6 as described for the two previous groups. There were no significant differences among any of the groups with respect to maternal weight gain, litter size, embryolethality, fetal weight, or crown-rump length. The offspring of nicotine treated animals showed a significantly higher incidence of hydrocephaly when compared to the controls, but in the combined treatment group no malformed fetuses were observed. Light microscopic examination of maternal liver, kidney and placentas revealed changes in the hepatic sinusoids, glomeruli and intervillous spaces after nicotine and combined treatment. In addition, the decidua basalis was poorly developed compared to the controls. Chorionic villi and fetal kidney appeared normal in all groups. A coteratogenic effect is not evident from these findings.

Neuropathology of congenital hydrocephalus in the SUMS/NP mouse

The neuropathology of congenital hydrocephalus in SUMS/NP mice was investigated in this study. Hydrocephalus occurred with an incidence of 16.5% and was evident in the form of an enlarged head soon after birth. The condition was progressive; affected mice gradually became noticeably smaller than normals, acquired functional disturbances and died before ever breeding. Hydrocephalic mice exhibited enormous dilatation of the lateral ventricles, thinning of the cortex and compression and distortion of the diencephalon and striatum. Examination of the midbrain in these animals revealed that the proximal cerebral aqueduct was diminished in size, occluded or absent. Evidence of its anomalous development was seen as early as day 15 of foetal development. This is in substantial agreement with previous reports on this strain. Although the mechanism by which this occurs is still unknown, abnormal development of the adjoining diencephalon and/or rostral midbrain is likely to be involved.

Embryopathic risks of cigarette smoking

Cigarette smoking has been associated with infertility, a higher frequency of spontaneous abortions, intrauterine growth retardation and an increased incidence of birth defects. Nicotine is the major pharmacological component of cigarette smoke. Its potential reproductive and teratological risks are critically reviewed.

Mechanisms of fetal alcohol effects: role of acetaldehyde

Pregnant rats were treated from day 9 through 12 of gestation with 12.5% ethanol, 25% ethanol, 1% acetaldehyde, cyanamide (an inhibitor of the enzyme aldehyde dehydrogenase), or a combination of cyanamide and ethanol. Embryos were recovered on gestational day 12 and were quantitatively assessed on the basis of 16 recognizable developmental endpoints (morphological scores). The head and the crown-rump lengths of the embryos were also measured. Total resorption occurred in two animals treated with cyanamide and two treated with cyanamide and ethanol. Acetaldehyde and ethanol (at both concentrations) were found to reduce the head length of the embryos but had no significant effects on morphological scores and crown-rump length. The combination of ethanol with cyanamide caused a greater reduction in head length and also significantly reduced crown-rump length, as well as the morphological scores. The results suggest that the deleterious effects of ethanol could be attributed to acetaldehyde, its primary metabolite, although other underlying factors cannot be ruled out.

Rat embryogenesis following exposure to alcohol and nicotine

Pregnant Sprague-Dawley rats were treated from day 9 through 12 of gestation with either ethanol (12.5% v/v in physiological saline, 0.015 ml/g, i.p.) and nicotine (16.7 mg/kg, s.c.), alone or in combination. Corresponding groups of animals received physiological saline in a similar manner and these served as controls. Embryos were recovered on gestational day 12 and were quantitatively assessed on the basis of 16 recognizable developmental endpoints (morphological scores). The head and the crown-rump lengths of the embryos were also measured. Embryos exposed to nicotine and to ethanol-nicotine were significantly affected in their development whereas those exposed to ethanol alone were spared.

Hereditary hydrocephalus in laboratory animals and humans

Cerebral ventricle dilatation secondary to disturbed flow of CSF has been observed as an inheritable trait in a variety of laboratory animals as well as in humans. In few groups, however, has the neuropathology been adequately elucidated. In most cases, defective development of the cerebral aqueduct or of the subarachnoid space has been observed. Further study is needed to understand the developmental mechanisms that fail and give rise to hydrocephalus in such models.

In vivo evaluation of teratogenesis and cytogenetic changes following methylmercuric chloride treatment

Mercury is a major environmental pollutant and a proven teratogen in man and animals. Its teratogenicity and effects on fetal chromosomes were investigated in mice. Various dose levels of methylmercuric chloride (MMC) were administered via an intragastric tube to pregnant ICR Swiss/Webster mice on day 9 of gestation. On day 18 of gestation the animals were killed and the fetuses were removed. Fetal lung and liver tissues were processed for cytogenetic studies. Fetuses were also fixed in Bouin's solution for subsequent teratological examination by using Wilson's technique. Mercury levels were determined in maternal blood and randomly selected fetuses. One fetus from each litter was processed for skeletal staining with Alizarin Red S. A significant increase in embryonic deaths and resorptions was observed at all dose levels. The incidence of fetal anomalies was significantly increased following maternal treatment with 10, 15, or 20 mg/kg of MMC. Maternal weight between day 9 and day 18 of gestation decreased significantly. The LD50 of MMC in pregnant mice was determined to be 20 mg/kg of body weight; the LD100 was 30 mg/kg. A significant difference was observed between the mean fetal weights at the various dose levels. Levels of mercury were found to be significantly higher in treated animals and fetuses, and increased in a dose-related manner. The levels of mercury were significantly higher in the fetuses than in the mothers at the same dosage, indicating a correlation between the levels of mercury in maternal mice and corresponding higher levels in their fetuses. Cytogenetic studies revealed significant clumping of chromosomes in metaphase at all dose levels and the frequency of clumping increased as dosage increased. The euploidy number (2n = 40) of chromosomes per cell did not vary between the treatment groups and control groups. The frequency of nucleolus-organizing regions per cell did not change significantly between the treatment groups and the control. The frequency of sister chromatid exchanges increased significantly as the dosage increased.

Cytostatic action of methylmercuric chloride on mammalian duodenal cells

Adult male mice of the ICR/Swiss Webster strain received a single intragastric administration of methylmercuric chloride 1,000 ppm, at dose levels of 5,10,15,20,25 and 30 mg/kg of body weight. The animals were killed six hours later. Tissue samples from the duodenum were fixed in 10% neutral buffered formalin for light microscopy. Chromosome clumping was observed in dividing cells at all dose levels, resembling a C-mitotic effect. It would lead to reduced mitotic cell formation on account of the subsequent lysis of the arrested metaphases. The cytostatic effect was brought about by the inactivation of the microtubule spindle fiber polymerization mechanism induced by methylmercuric chloride. There was a direct positive correlation between the varying dose levels of methylmercury and the proportion of cells arrested in metaphase in the crypts of the duodenum.

Possible prenatal hydantoin effect in a child born to a nonepileptic mother

We describe a child who was born with marked digital hypoplasia of his right hand. Although the mother was not an epileptic, the child was exposed in utero to diphenylhydantoin.

Light and electron microscopic study of fetal lung following maternal exposure to methylmercuric chloride

Varying dose levels of methylmercuric chloride (MMC), 1000 ppm (5 mg through 15 mg/kg of body weight), were administered via an intragastric tube to pregnant ICR Swiss/Webster mice on day 9 of gestation. The animals were killed on gestational day 18 and the fetuses removed. Fetal lung sections were processed for light and electron microscopy. A group of animals treated with physiological saline in a similar manner served as the controls. The fetal lungs from treated animals were hypoplastic and retarded in development. The severity of pulmonary changes increased with the dose-levels of MMC. Vacuolation and lysis of mitochondria were seen in fetal lungs. Mitochondrial damage increased in severity with dose-level of methylmercuric chloride.

Fetal outcome following maternal treatment with prostaglandin E2

Pregnant Sprague-Dawley rats were treated subcutaneously with PGE2 at doses of 50, 100 and 200 micrograms on gestational days 5 through 8. Control animals received physiological saline in a similar manner. On day 20 of gestation the animals were anaesthetized and fetuses were removed by hysterotomy. All fetuses recovered were alive and appeared normal. The incidence of fetal resorptions was not significantly increased. Visceral abnormalities and skeletal defects were not observed in the offspring. Also, the mean weight of treated fetuses was not significantly different from that of the corresponding controls.

Cardiovascular primordium of the rat embryo following in utero exposure to alcohol and caffeine

The influence of alcohol and caffeine on cardiac embryogenesis was investigated in the rat. No disturbances were detected in the yolk sac circulatory system and allantois of embryos exposed to ethanol, but in several cases the cardiac tube was delayed in its development. Caffeine had no gross morphological effect on the developing cardiovascular system. However, cardiac morphogenesis was significantly impaired in embryos recovered from mothers treated with both ethanol and caffeine.

Embryopathic effects of caffeine in the chick

There is increasing concern about the potential teratogenic effects of caffeine. Laboratory rodents were widely used for the teratological evaluation of caffeine. However, few studies have been carried out in non-mammalian organisms. Caffeine, dissolved in sterile water, was injected into the air sacs of fertile White Leghorn chick eggs at doses of 100, 200, 300, 400, 500, 700, 900, and 1,100 micrograms per egg. Control eggs were injected with an equivalent volume of sterile water (0.1 ml/egg). The embryos were treated at either 48, 72, or 96 hours incubation. On day 9, live embryos were recovered and examined for external malformations after staging and weighing. Treatment with 400 and 1,100 micrograms caffeine at 48 hours incubation resulted in a significantly high incidence of abnormal embryos, compared to the controls. The most common malformations included reduced body, microphthalmia, exencephaly, everted viscera and short neck. A significant number of embryos died following treatment with 1,100 micrograms caffeine at 48 hours incubation, and 400 and 700 micrograms at 72 hours incubation. Embryonic growth was not affected. Even though it is not possible to extrapolate these findings directly to humans, moderation in the consumption of caffeine-containing beverages during pregnancy is recommended.

Early embryonic development in the rat after maternal treatment with PGE2

Pregnant Sprague-Dawley rats were treated subcutaneously with PGE2 at doses of 50, 100, and 200 microgram on gestational days five through eight. Control animals received the solvent in a similar manner. On gestational day 9 the animals were killed by intracardiac perfusion with Karnovsky's fixative, uteri were removed, and a transverse central slice from each implantation site was embedded in araldite. The conceptus was located and 2-3 micron sections were made of each implantation site and examined at the light microscopic level. No significant structural changes were induced in any of the conceptuses, but an unusually wide range of embryonic stages was detected in both the control and the experimental groups of animals.

Further studies on the interaction of ethanol and nicotine in the pregnant rat

Because alcohol and cigarette smoking are considered to be deleterious to the fetus, the combined effect of ethanol and nicotine during pregnancy was investigated. Pregnant Sprague-Dawley rats receiving a liquid alcohol diet at moderate dose-levels from gestational day 1 through 12, and a continuous subcutaneous infusion of nicotine from gestational day 6 through 12, revealed no significant reproductive and developmental disturbances.

Protection against ethanol-induced embryonic damage by administering gamma-linolenic and linoleic acids

Many reports have now confirmed the teratogenic potential of alcohol in humans and in laboratory animals. A characteristic pattern of congenital anomalies is present in infants born to mothers suffering from chronic alcoholism. The pathogenesis of this condition is unclear. Chronic consumption of ethanol causes a depletion of essential fatty acids, partly by blocking gamma-linolenic acid formation and partly by depleting dihomogammalinolenic acid. Whether this action of ethanol on essential fatty acid and prostaglandin metabolism may account for its teratogenic potential was investigated in the rat. Treatment of pregnant rats with ethanol and evening primrose oil (efamol), a rich source of gammalinolenic acid, led to a significant reduction in the embryopathic activity of ethanol.

Pregnancy and fetal development in hamsters treated with prostaglandin F2 alpha

The influence of PGF2 alpha on pregnancy and fetal outcome was investigated in the hamster. Following subcutaneous treatment with 50, 100, 200, 400, and 800 micrograms PGF2 alpha prenatal loss was significantly increased only at the highest dose level. The offspring of the treated animals were all alive and normal. Fetal weight was not affected. However, following intravenous injection of 100 and 200 micrograms PGF2 alpha there was a significant reduction in fetal weight, and at the 400 micrograms dose level an increase in fetal indicate that PGF2 alpha is not teratogenic in hamsters despite the apparent greater sensitivity of the hamster embryo to prostaglandin.

Prostaglandin F2alpha conceptus-endometrial interaction during early gestation in the mouse

Pregnant Swiss-Webster mice were treated subcutaneously with 50, 100 or 200 microgram PGF2alpha on day 4, 5 or 6 postcoitum (p.c.). Twelve hours later, the animals were killed by intracardiac perfusion with Karnovsky's fixative, uteri were removed and a transverse central slice from each implantation site was embedded in Araldite. The conceptus was found by thick sectioning. Thin sections were taken of each implantation site and examined at the electron microscopic level. PGF2alpha administered at a dose of 100 microgram per animal on day 4 p.c. altered the normal attachment of the blastocyst to the endometrium, as well as formation of the implantation chamber. Cytology of the epiblast and hypoblast was adversely affected by this change. Dosages of 100 or 200 microgram PGF2alpha per animal adversely affected the apical trophectoderm cell of the blastocyst. Treatment with PGF2alpha on day 4 p.c. at a dose of 50 microgram per animal reduced the decidual reaction around the implantation chamber while treatment on day 5 p.c. at a dose of 50 or 100 microgram per animal was associated with an advanced stage of development. Treatment on day 6 p.c. did not appear to have any influence on implantation or blastocyst development.

Development of the chick embryo following PGE1 treatment

Chick embryos were treated with prostaglandin E1 (10, 20, 30, and 50 micrograms) at 48 and 72 hours incubation. Live embryos were recovered on day 9, staged, and examined for external malformations after weighing. There was no significant increase in embryonic mortality and malformation rates compared to the controls. Embryonic growth was also not affected.

Embryopathic effects of thromboxane B2 in the chick

Several prostaglandins of the E and F series are now known to be involved in reproduction and developmental events. However, there is as yet no such evidence for any of the other arachidonate metabolites. Thromboxane B2 is the stable metabolic end product of the biologically active but unstable intermediate thromboxane A. Administered to developing chick embryos at 48 and 72 hours incubation, thromboxane B2 caused growth retardation and induced a high incidence of anomalies, in particular, everted viscera.

Prostaglandin F2 alpha effects on the early mouse embryo

Subcutaneous treatment of pregnant mice with 50, 100 and 200 micrograms PGF 2 alpha on gestational day 5 and 200 micrograms on gestational day 3 or 6 resulted in fetal growth retardation. Litter size was significantly reduced following treatment with 50 micrograms or 100 micrograms PGF 2 alpha on day 6 of pregnancy and the incidence of resorptions was increased following treatment with 50 micrograms on gestational day 6.

Distribution of prostaglandin F1 alpha in the pregnant rat

The placental transfer and tissue distribution of tritium-labelled prostaglandin F1 alpha was investigated in rats on day 14 of gestation. Low levels of radioactivity were detected in the embryos and placentas 5, 10, 60, and 120 minutes after administration of the prostaglandin, but the concentration in amniotic fluid was extremely high at all time intervals. Maternal serum, kidney, liver and lung revealed a greater uptake of the isotope compared to the uterus, ovary, spleen and brain. It is conceivable that the high levels of prostaglandin accumulated in the amniotic fluid may act directly on the conceptus.

Pregnancy and progeny in rats treated with prostaglandin F1 alpha

Studies on the influence of PGF1 alpha on reproductive processes in humans and laboratory animals are lacking. PGF1 alpha was administered s.c. to pregnant Sprague-Dawley rats at doses of 50, 100, and 200 micrograms, respectively, from days 12 through 15 of gestation. The offspring, recovered by cesarean section on gestational day 20, were all alive and showed no anomalies. The incidence of fetal resorptions was not significantly increased. However, PGF1 alpha caused intrauterine growth retardation and placental damage. There was no morphological evidence of luteolysis.

Effect of ethanol and nicotine in the pregnant rat

Treatment of pregnant Sprague-Dawley rats on day 9 of gestation with both ethanol (0.02 ml/gm of a 12.5% or 25% solution, i.p.) and nicotine (5 mg/kg, s.c.) resulted in no significant adverse effects on embryonic development and fetal viability.

Influence of pyrazole, an inhibitor of alcohol dehydrogenase on the prenatal toxicity of ethanol in the rat

Pyrazole, a potent inhibitor of alcohol dehydrogenase, induced a high incidence of ocular and urinary bladder anomalies in the offspring of rats following treatment on gestational day 9. A single moderate dose of ethanol potentiated the teratogenic action of pyrazole, but alone did not affect embryonic development.