Prenatal rupture of a left ventricular diverticulum: a case report and review of the literature

Congenital left ventricular diverticulum is a rare malformation. We report a case of a ruptured congenital left ventricular diverticulum in a 24-week-old fetus. The fetus was referred for a large and circumferential pericardial effusion confirmed by cross-sectional echocardiography in our tertiary fetal cardiology unit. Pericardiocentesis removed 25 mL of old hematic fluid. The fetus died 5 days later. The pathological examination showed a ruptured submitral fibrous diverticulum of the posterior wall of the left ventricle. There is no previous report in the literature of prenatal rupture of a cardiac diverticulum. The submitral location and the fibrous wall of the diverticulum is uncommon. As regards this case, we reviewed the diagnostic criteria and the outcome of 11 cases of prenatal cardiac diverticulum reported in the literature.

Abnormal embryonic development diagnosed embryoscopically in early intrauterine deaths after in vitro fertilization: A preliminary report of 23 cases

OBJECTIVE

To provide data about the phenotypic appearance of the embryo of early failed pregnancies after IVF.

DESIGN

Clinical prospective descriptive study.

SETTING

Tertiary care center.

PATIENT(S)

Twenty-three women who had conceived by IVF and had a missed abortion before 12 weeks of gestation.

INTERVENTION(S)

Embryoscopic examination of the embryo before curettage. Cytogenetic analysis of the chorionic villi by standard G-banding cytogenetic techniques or by comparative genomic hybridization in combination with flow cytometry analysis.

MAIN OUTCOME MEASURE(S)

Embryonic phenotype and karyotype were determined.

RESULT(S)

Twenty-one of 23 IVF embryos showed structural defects on embryoscopic examination. Seventeen of 23 specimens had a chromosomal abnormality. The majority were numerical aberrations such as monosomy X (2 cases). Trisomies for chromosomes 18 (one case), 16 (three cases), 15 (one case), 14 (two cases), 13 (one case), 12 (one case), 11 (one case), 10 (one case), 9 (one case), 8 (one case), and 3 (one case) were observed. A structural chromosome anomaly leading to a chromosomal trisomy was observed in one case. Aneuploidy explained the grossly abnormal embryonic development documented by embryoscopy in 15 of 21 cases.

CONCLUSION(S)

Aneuploidy is the major factor affecting normal embryonic development in missed abortions after IVF. Further investigation is needed to elucidate mechanisms that might prevent normal embryogenesis but evade detection by the cytogenetic techniques used in the present study.

Targeted disruption of the Walker-Warburg syndrome gene Pomt1 in mouse results in embryonic lethality

O-mannosylation is an important protein modification in eukaryotes that is initiated by an evolutionarily conserved family of protein O-mannosyltransferases. The first mammalian protein O-mannosyltransferase gene described was the human POMT1. Mutations in the hPOMT1 gene are responsible for Walker-Warburg syndrome (WWS), a severe recessive congenital muscular dystrophy associated with defects in neuronal migration that produce complex brain and eye abnormalities. During embryogenesis, the murine Pomt1 gene is prominently expressed in the neural tube, the developing eye, and the mesenchyme. These sites of expression correlate with those in which the main tissue alterations are observed in WWS patients. We have inactivated a Pomt1 allele by gene targeting in embryonic stem cells and produced chimeras transmitting the defect allele to offspring. Although heterozygous mice were viable and fertile, the total absence of Pomt1(-/-) pups in the progeny of heterozygous intercrosses indicated that this genotype is embryonic lethal. An analysis of the mutant phenotype revealed that homozygous Pomt1(-/-) mice suffer developmental arrest around embryonic day (E) 7.5 and die between E7.5 and E9.5. The Pomt1(-/-) embryos present defects in the formation of Reichert's membrane, the first basement membrane to form in the embryo. The failure of this membrane to form appears to be the result of abnormal glycosylation and maturation of dystroglycan that may impair recruitment of laminin, a structural component required for the formation of Reichert's membrane in rodents. The targeted disruption of mPomt1 represents an example of an engineered deletion of a known glycosyltransferase involved in O-mannosyl glycan synthesis.

Thrombophilia is not associated with an increase in placental abnormalities in women with intra-uterine fetal death

BACKGROUND

The aim of this study was to investigate whether women with thrombophilia and intrauterine fetal death have a higher incidence of placental lesions as compared with those without thrombophilia.

METHOD

In a case-control study comprising 50 women with an obstetrical history of intrauterine fetal death, placental histology comparison was made between those with thrombophilia and those without thrombophilia.

RESULTS

Of the women who had an intrauterine fetal death, eight (16%) had a thrombophilia factor. There were no differences in birth weight, gestational age and parity or in placental volume and weight between the eight women with and the 42 women without thrombophilia. There was no statistically significant difference between placentas of the women with and those without thrombophilia.

CONCLUSION

In a group of women who had an obstetrical history of intrauterine fetal death, those with thrombophilia do not have a difference in placental histological lesions compared with the women without a thrombophilia factor. Future thrombophilia research should be focused on placental bed specimens.

An allelic series of mutations in Smad2 and Smad4 identified in a genotype-based screen of N-ethyl-N- nitrosourea-mutagenized mouse embryonic stem cells

Using selectable genes as proof of principle, a new high-throughput genotype-based mutation screen in mouse embryonic stem (ES) cells was developed [Chen et al. (2002) Nat. Genet. 24, 314-317]. If expanded to nonselectable genes, this approach would allow one to proceed quickly from sequence to whole-animal phenotypes. Here data are presented showing that a screen of a cryopreserved library of clonal, germ line competent, N-ethyl-N-nitrosurea (ENU) mutagenized ES cells can identify a large series of allelic mutations in Smad2 and Smad4, two nonselectable genes of the transforming growth factor beta superfamily of signaling molecules. Whole animal phenotypic analyses of some of these alleles provided evidence for novel developmental processes mediated by these components of transforming growth factor beta signaling, demonstrating the utility of non-null alleles created by chemical mutagens. The accurately assessed mutation load of the ES cell library indicates that it is a valuable resource for developing mouse lines for genetic and functional studies. This methodology can conceptually be applied for the generation of an allelic series of subtle mutations at any locus of interest in the mouse.

The origin of monozygotic twinning

The incidence of monozygotic twinning appears to be increasing within the field of assisted human reproduction. Many theories have been put forward as to how and when this occurs. Whatever the cause, the normal events of embryo development, which necessarily involve axis formation, patterning and polarization, need to be adhered to in order to obtain a viable offspring. This paper describes the course of development in terms of axis formation and polarity and offers suggestions as to how either a disruption of this or duplication events in the course of the formation of these parameters could prevent or contribute to a twinning event. The likelihood of twinning occurring at any point is discussed in terms of the establishment of polarity and axes.

Does the fetus lose weight in utero following fetal death: a study in preterm infants

OBJECTIVE

To evaluate whether the fetus loses weight in uttero following fetal death, looking specifically at weight differences according to whether the death occurred during labour or before labour.

DESIGN

Record linkage of maternity data and perinatal mortality data.

SETTING

Scotland, UK. Population A group of 8,069 singleton live and stillbirths without obvious congenital abnormalities delivered at 24-32 weeks.

MAIN OUTCOME MEASURE

Birthweight.

RESULTS

Stillborn infants weighed less than liveborns of equivalent gestational age at delivery. Stillborn infants in whom the death occurred during labour weighed more than those in whom the death occurred before labour; this applied to both vaginal deliveries and those by caesarean section.

CONCLUSIONS

These findings could be attributed to the hypothesis that the low birthweight of stillborn infants is due to weight loss following the death, in addition to any process of growth restriction before the death. The analysis described here contains no data which would negate this hypothesis.

Adverse perinatal outcome of twin pregnancies according to chorionicity: review of the literature

Twin gestations are at significant increased risk for adverse perinatal outcome. As a result, although prospective randomized data is lacking, increased fetal surveillance has been advocated for twins. Growth concordance is considered a reassuring sign in twins and conversely, discordancy to possibly reflect a hostile intrauterine environment at least to the smaller twin. Consequently, increased surveillance of discordant twins is commonly practiced. Monochorionic twins are at further risk for type-specific perinatal complications, for example, twin-twin transfusion syndrome. Recently, precise first-trimester depiction of chorionicity has enabled early antepartum stratification of twin gestations according to chorionicity, in comparison with previous later (mid- and third-trimester) ultrasonographic diagnosis of chorionicity. This immediately leads to the question whether antenatal testing of twins should differ according to chorionicity? Review of the literature supports that despite the existence of complications unique to monochorionic twin gestations, dichorionic twins sustain an increased risk of adverse perinatal outcome (such as fetal growth restriction) in comparison with singletons, and that close antenatal fetal surveillance of twins should be performed, irrespective of chorionicity.

Paternal transmission of the mouse Thp mutation is lethal in some genetic backgrounds

Thp is a large deletion on chromosome 17 which includes the maternal lethal gene Tme. Documentation of inheritance patterns suggests that Tme is an imprinted gene which is required for viability; maternal deletion is lethal while paternal deletion is viable. However, paternal transmission of Thp is rarely the expected 50%. We show here that paternally inherited Thp is lethal in some strains, providing evidence of an incompletely penetrant, dosage sensitive lethal allele of a locus that probably maps to the hairpin tail region of chr. 17. Interpretation of the various phenotypes associated with loss of the putative Tme gene, Igf2r, may need to be revised in view of these observations.

Fetal death after normal biophysical profile score: An eighteen-year experience

OBJECTIVE

It was our goal to determine the false-negative rate of the biophysical profile, characterize an 18-year variation in the false-negative rate, examine the relationship between the last normal biophysical profile score and death, and compare the false-negative rate of 2 disparate populations.

STUDY DESIGN

Biophysical profile scores of 86,955 patients at 2 medical centers were collected and recorded prospectively. All perinatal deaths occurring within 1 week of a normal score were similarly recorded. The annual false-negative rate, the cumulative false-negative rate, and the ratio of false-negative results in cases of subsequent fetal death to the perinatal mortality rate were calculated.

RESULTS

There were 65 fetal deaths among 86,955 fetuses. Over an 18-year study period at one institution, the false-negative rate varied but not significantly. The cumulative false-negative rate was 0.708 per 1000 at one medical center studied and 2.289 per 1000 at the other center. The average interval between last normal score and fetal death was 3.62 days and did not vary significantly between the medical centers.

CONCLUSIONS

False-negative results in cases of subsequent fetal death reflect events that are subsequent to the last normal test result. Fetomaternal hemorrhage was the single most identifiable fetal cause of false-negative results in cases of subsequent fetal death. The ratio of the false-negative rate in cases of subsequent fetal death to the perinatal mortality rate should be used as a more objective approach to reporting this value, because the false-negative rate likely reflects the underlying perinatal mortality.

Tetraploid embryos rescue embryonic lethality caused by an additional maternally inherited X chromosome in the mouse

Mouse embryos with an additional maternally inherited X chromosome, i.e., disomic for XM (DsXM), cease to grow early in development and have a deficient extraembryonic region. We hypothesized that the underdeveloped extraembryonic region is attributed to two copies of XM that escape inactivation due to maternal imprinting. To examine the validity of this hypothesis and throw more light on the significance of X chromosome dosage on cell differentiation, we generated DsXM(XMXMXP and XMXMY) embryos at a high frequency taking advantage of the elevated incidence of X chromosome nondisjunction in female mice heterozygous for two Robertsonian X-autosome translocations, Rb(X.2)2Ad and Rb(X.9)6H. Although two XM chromosomes seem to remain active in both trophectoderm and primitive endoderm, detailed histological examination showed that the polar trophectoderm derivatives (ectoplacental cone and extraembryonic ectoderm) are severely affected, but the primitive endoderm derivatives (visceral and parietal endoderm) are relatively unaffected. Successful rescue of DsXM embryos by aggregation with tetraploid embryos show that X chromosome inactivation occurred normally leaving one X active in epiblast derivatives. Thus, two copies of active XM chromosome in cells of the polar trophectoderm cell lineage seem to be the main cause of early lethality shown by DsXM embryos as a result of failure in formation of ectoplacental cone and extraembryonic ectoderm.

Antenatal diagnosis of brain damage in the survivor after the second trimester death of a monochorionic monoamniotic co-twin: case report and literature review

At 28 weeks of amenorrhea, 1 fetus of a monoamniotic twin pregnancy died. Ultrasound and Doppler investigations of the surviving twin were normal. Three weeks later, endovaginal ultrasound and magnetic resonance imaging revealed massive bilateral cerebral ischemic necrosis in the surviving twin. In utero fetal blood sampling carried out before the termination did not reveal either anemia or thrombopenia. Current data suggest that cerebral or renal ischemic complications could set in immediately after the death of the first twin as a result of a period of acute hypotension. At least 2 weeks are necessary for them to be identifiable by ultrasound. It seems that they cannot be prevented by prompt delivery of the second twin.

Mummified fetus in a mare

A 12-year-old Arabian mare with a history of repeated early embryonic losses gave birth to a mummified fetus. The fetus was not the result of a pregnancy with twins. The mare had been given a progestogen throughout gestation and expelled the mummified fetus at about 325 days of gestation, 2 weeks after progestogen treatment was discontinued. We estimate that the size of the fetus was consistent with a fetal age of 5 months. The mare and mummified fetus illustrated that progestogen administration after 100 days of gestation can promote retention of a nonviable fetus. When the fetoplacental unit is incapable of producing progestogens in adequate amounts for pregnancy maintenance at that stage of gestation, then it is also unlikely to provide sufficient oxygen and nutrients to meet the needs of the growing fetus. Monitoring fetal viability would enable practitioners to prevent prolonged retention of a nonviable fetus.

The absence of the blood clotting regulator thrombomodulin causes embryonic lethality in mice before development of a functional cardiovascular system

We have targeted the murine thrombomodulin (TM) gene in embryonic stem cells and generated embryos as well as mice with TM deficiency. The heterozygous TM-deficient (TM+/-) mice as compared to wild-type (TM+/+) littermates exhibit 50% reductions in the levels of TM mRNA and TM protein. However, TM+/- mice appear normal and are free of thrombotic complications. The homozygous TM-deficient (TM-/-) embryos die before E9.5. An overall retardation in growth and development of TM-/- embryos is first evident on E8.5 (8-12 somite pairs). However, no specific pathologic abnormalities are observed. These initial changes take place at a time when TM is normally expressed in the endoderm of the parietal yolk sac. The removal of E7.5 TM-/- embryos from maternal decidua and their subsequent culture in vitro allows development to proceed to stages not observed in vivo (13-20 somite) with the appearance of normal blood vessels in the visceral yolk sac and embryo. The results of our studies suggest that the failure of TM-/- embryos to survive at mid-gestation is a consequence of dysfunctional maternal-embryonic interactions caused by the absence of TM in the parietal yolk sac and demonstrate that the receptor is necessary for normal embryonic development in utero.

Death before birth: clues from gene knockouts and mutations

A survey of mouse gene knockouts, transgene insertions and spontaneous mutations that are lethal prenatally reveals that surprisingly few developmental disturbances lead to death of the embryo and early foetus. These disturbances include failure to establish and maintain a vascular circulation, and failure to make the transition from yolk-sac-based to liver-based haematopoiesis. The embryo must also establish gestation-dependent routes of nutritional interaction with the mother, including implantation, formation of a yolk-sac vascular circulation, and formation of a chorioallantoic placenta. A number of embryonic organ and body systems, including the central nervous system, gut, lungs, urogenital system and musculoskeletal system, appear to have little or no survival value in utero.

[Morphological changes in the primordia of the deciduous teeth during an exacerbated course of the antenatal period]

Histologic examination of 380 rudimentary deciduous teeth of 91 stillborn babies or corpses of newborns dead within 16 days after birth and comparison of the results with clinical data brought the authors to a conclusion that the diagnosis of enamel hypoplasia is erroneous because all dental tissues are involved during this condition. Pathohistologic changes in the enamel, dentin, and tissues adjacent to dental rudiment are described in detail, all these tissues developing under unfavorable conditions of antenatal odontogenesis.

[The ultrastructure of the pancreatic endocrinocytes of human fetuses in postmortem autolysis]

The method of electron microscopy was used to study the morpho-functional state of pancreatic islands of human fetuses at different terms (10-54 h) after clinical death. Within the periods of time in question the island secretory cells preserve the structure characteristic of each type (B, A, D). The development of symptoms of postmortem autolysis of the pancreatic island is not a chaotic fleeting physico-chemical reaction and is characterized by a definite sequence of cytological changes of endocrinocytes. A conclusion is made that cadaveric material of the pancreas is good for preparing the pancreatic island culture for using it in the following tissue substituting therapy of patients with diabetes mellitus.

[Observations on the maturity of stillborn calves]

Organ weight and trace element analyses were performed on 75 stillborn calves from the same dairy cow herd. The elements Fe, Mn, Zn and Cu were measured in the livers of 66 of the calves. The calves ranged in age from 259 to 299 days of gestation, and in weight from 18 to 58 kg. Based on the quotients of organ and other body parts, stage of growth of the humerus and age, the animals were grouped as either preterm (P), term but light (TL), and term with appropriate weight (TA) calves. In P group calves the heart, lungs, liver, kidneys, thymus, spleen and thyroid glands were relatively heavy. In the TL group calves the brain, heart, lungs and thyroid glands were relatively heavy whereas the spleen and thymus were comparatively light. The liver Fe and Zn values were lower in this group than in the other 2 groups.

[Adrenal structure in the fetuses of humans living in the European North]

The adrenals of 194 human fetuses of 17-40 weeks and newborn infants were studied by histological and morphometrical methods. The abortive material was taken at hospitals in the city of Arkhangelsk and regions beyond the Polar circle. The mass of adrenals was found to be reliably less as compared with the norms in middle latitudes, and the rate of increase of this index decreased in the dynamics of pregnancy. The microscopic and stereometric investigations have revealed decreased thickness of the cortex, adaptational and pathological changes of adrenocorticocytes. Little mass of the adrenals was associated in some cases with a premature formation of the cortex zones.

The effect of intrauterine growth retardation on the development of renal nephrons

OBJECTIVE

To investigate the effect of Type II (asymmetrical) intrauterine growth retardation (IUGR) on renal development.

DESIGN

A prospective descriptive study.

SETTING

Department of Fetal and Infant Pathology, Liverpool Children's Hospital.

SUBJECTS

Six (severely) affected IUGR stillbirths of known gestational age with a control group of stillbirths with birthweight greater than 10th centile, and eight liveborn IUGR infants who died within a year of birth with a control group of appropriately grown infants who died within a year of birth (postnatal groups).

TECHNIQUES

The kidneys from all the groups studied were analysed using unbiased, reproducible and objective design-based stereological techniques.

MAIN OUTCOME MEASURES

Total renal nephron (glomerular) numbers and average volumes of total nephron and cortical and medullary nephron segments.

RESULTS

Nephron number estimates lay below the control group's 5% prediction limit in five out of the six growth-retarded stillbirths, and were significantly (P less than 0.005, IUGR at 65% of the control mean) reduced in the postnatal group. Estimates of nephron (segment) volume did not differ between control and IUGR groups.

CONCLUSIONS

Type II intrauterine growth retardation may exert a profound effect on renal development. The reduced nephron number at birth, together with the lack of any early postnatal compensation in either nephron number or nephron size, emphasizes the need for vigorous antenatal surveillance for IUGR and consideration of elective preterm delivery of affected fetuses. A systematic review of other organs, which develop in a similarly rapid fashion during the late intrauterine period, is indicated by this work. With one exception, all birthweights in the growth-retarded groups were below the third centile, thus the precise quantitative relation between progressive IUGR and renal function requires further assessment.

Fetal disruptions: assessment of frequency, heterogeneity, and embryologic mechanisms in a population referred to a community-based stillbirth assessment program

The Wisconsin Stillbirth Service Project (WiSSP) is a community-based program for the investigation of the cause of fetal death. From its inception in 1983 through July 1988, 629 referrals were made to WiSSP. All referrals were assessed for the presence of disruptional characteristics, and 23 were found to have major or primary disruptive effects. Most of these were either early amnion disruption/limb-body wall disruption (treated as a single group, since analysis suggests a continuum of clinical characteristics) and twin-twin disruptions. Therefore, disruptions accounted for 3.6% of all referrals (including liveborn and miscarriage referrals) to WiSSP. When only stillborn fetuses are considered, approximately 2.4% appear to have died because of disruptions. This makes disruptions one of the most frequent, identifiable causes of late intrauterine death. We estimate that 0.6-1.4% of all stillborn fetuses die because of early amnion disruption/limb-body wall disruption which, when taken with previous estimates of the frequency of such problems in early miscarriages and liveborn infants, suggests that these disruptions result in a 95% prenatal mortality rate. We suggest a unified model of likely pathogenetic mechanisms which may help explain the continuum of multisystem involvement seen in those with early amnion disruption/limb body wall disruption. In addition, 3 patients with atypical disruptions are reviewed who exemplify the difficulty and importance of differentiating disruptional and malformational processes.

A population study of the relationship between fetal death and altered fetal growth

In order to describe the relationship between fetal death rate and impaired fetal growth, we examined over 850,000 births in Illinois between 1980-1984 (using the state computer data file) and assessed the mean/modal birth weights at each gestational age and the relationship between birth weight and fetal death rate at each gestational age. We were interested in the following questions: 1) Is the relationship between impaired fetal growth and fetal death rate the same at each gestational age? and 2) What birth weight would result in a quadrupling of the fetal death rate at each gestational age? Using exponential regression analysis, we determined for each gestational age the fetal death rate at the modal birth weight and similarly, the birth weight expected to result in a quadrupling of the fetal death rate. As gestational age advanced, the birth weight percentile resulting in the constant outcome also increased (second percentile at 25 weeks; 17th percentile at 42 weeks). We also compared these data with similar data from Denver. The findings indicate the following: 1) Fetal death rate increases exponentially as birth weight decreases at each gestational age; 2) the birth weight percentile that results in a constant outcome is not consistent at each gestational age; and 3) if assessment of risk is to be inferred based on the relationship between birth weight and gestational age, the tenth percentile (whether Denver, Illinois, or elsewhere) does not predict stillbirth accurately. The implications point to the use of outcome-oriented risk assessments to predict fetal death when examining the relationship between birth weight and gestational age.

[Surfactant surface activity and ultrastructural changes in the type-II alveolocytes of fetal and neonatal lungs in experimental inflammation of the maternal lungs]

The lungs of 19 guinea pigs, born from 8 females in which acute and chronic pneumonia had been modelled by transtracheal introduction of sterile fishing-line were investigated. It was established, that in guinea pigs, born in females with acute and chronic pneumonia, the functional immaturity of pneumocytes of the 2-nd type took place. The functional immaturity of pneumocytes of the 2-nd type results in suppression of the surface active characteristics of surfactant.

Normal length of the human fetal gastrointestinal tract

Little information is available on the normal length of the gastrointestinal tract in fetuses or on factors that may affect its growth. To determine normal growth patterns of the fetal intestine, 58 fetuses received in the Central Laboratory for Human Embryology between January 1, 1987, and July 1, 1988, in which no abnormalities were noted on autopsy, were studied. The gastrointestinal tract was removed from the fetus en bloc from the esophagogastric junction to the pelvic floor and dissected. Measurements of stomach, small and large intestines, and appendix length were made and correlated with gestational age as determined by footlength. Overall growth of the gastrointestinal tract as well as that of each component was linear with respect to gestational age. In addition, five fetuses with omphalocele, 16 with cardiac malformations, and 20 with chromosomal abnormalities were studied. The total lengths of the gastrointestinal tracts in the first group were below the normal range in four of five fetuses. Those with cardiac defects had intestinal lengths below the mean, but the measurements were abnormal in only three. In both groups those fetuses with chromosomal abnormalities appeared to have shorter intestinal tracts than those with normal or unknown karyotypes. The gastrointestinal tracts of aneuploid fetuses fell within the normal range until approximately 20 weeks gestation, after which growth decreased. This growth failure may reflect the growth retardation seen in fetuses with chromosomal abnormalities.

The Farber lecture. Prenatal and perinatal death: the future of developmental pathology

It seems evident that most of "humanity" dies before, not after birth and that perhaps only one-third survive from earliest beginnings until birth or the end of the first year of life. As many as 50% of all human ova may have a chromosome abnormality with over 99% mortality, making this type of genetic defect not just the commonest cause of death prenatally and the cause of a substantial proportion of the malformations of abortuses and fetuses, but the commonest cause of death in humans altogether. This study, along with numerous studies before it, is the most convincing justification for doing autopsies on pre- and perinatally dead embryos and fetuses. With appropriate supervisory collaboration from a university pediatric pathology unit, such studies can be done efficiently at secondary-care centers, including some in rather remote locations. Thus, there exists no excuse anymore for not doing such studies which, in a high proportion of cases, will give the parents and attending physicians an explanation of the events and observed abnormalities with a chance in all cases at correct diagnostic and genetic counseling, appropriate monitoring of the next pregnancy, and an improved possibility of population monitoring for teratogens and substantial increases in the mutation rate. These immediate benefits to patients and the quality of medical care are the major, but not the only, justification for doing fetal pathology. Literally thousands of new discoveries still await the investigator with a prepared mind and will afford many research opportunities to those with an interest in normal and abnormal human development. And if it can be resolved in present-day pathology training programs how to attract greater numbers of interested residents and fellows into the field and to motivate them to take the additional training to become expert in developmental and genetic analysis, then "developmental" pathology will be facing a very bright future indeed.

Embryotoxic effects of magnesium deficiency and stress on rats and mice

Pregnant rats an mice received a magnesium (Mg)-deficient diet with different Mg contents from 40 t 360 ppm. The control received 2,000 ppm. At the end of gestation, the Mg concentration in the maternal serum was found to have decreased by up to 0.3 mmole/liter, depending on the Mg content of the food. Mg-dose-dependent embryotoxic effects (resorptions, retardation, disturbed bone development, and skeletal malformations) were observed only below a threshold value of 0.7 mmole/liter of the maternal serum Mg concentration. Noise stress in rats, in addition to a mild Mg deficiency (360 ppm Mg), which by itself had no effects, increased the rate of resorptions only.

[Embryo survival rate of BALB and C57BL line mice in reciprocal transplantations at early stages of development]

Survival rate and weight were studied for the BALB/c and C57Bl/6J mice embryos developed from transplanted 2- and 3-day-old blastocysts. The greatest number of implantations was observed when 3-day-old blastocysts were transplanted to recipient females with two-day pregnancy. The number of implantations and successfully developing transplanted embryos was increased in recipient female with a higher number of corpora lutea.