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PubMed1999

Effects of static electromagnetic fields on chick embryo pineal gland development.

The effects of static electromagnetic fields on the development of the chick embryo pineal gland were studied. A total of 144 fertilized White Leghorn eggs were sacrificed after 5, 10 and 15 days of incubation. The stage of development was determined in all embryos using the Hamburger and Hamilton method [J Morphol 49: 88-92, 1951]. The various morphometric parameters (diameter and distance of the pineal gland and its lumen) were measured on serial 7-micron-thick sections. The data were obtained in a morphometer and processed statistically. The intensities of the static electromagnetic fields were 18 and 36 mT. Control and exposed embryos were equally distributed and randomly assigned. After 5 days of incubation, 25% of embryos exposed to a static electromagnetic field of 18 mT had a more advanced stage of development than controls and embryos exposed to 36 mT. On the 10th and 15th day, embryos exposed to either 18 or 36 mT tended to be more developed than controls. In the morphometric study, results were similar for the controls and exposed embryos after 5 and 10 days of incubation. However, the values of the 15-day-old embryos exposed to static magnetic fields were lower than the values of the controls (p > 0.01). These differences were more pronounced in the embryos exposed to 36 mT. These results seem to indicate that static electromagnetic fields affect the development and growth of embryos unequally, and that their action can depend not only on the intensity of the static electromagnetic field, but also on the length of exposure and the organ which is developing. It may be interesting to use these data in ultrastructural and physiological studies.

Animals↗
PubMed2003

Evaluation of bovine embryos produced in high performance serum-free media.

This review evaluates the quality of bovine embryos developed from in vitro-matured (IVM) and -fertilized (IVF) oocytes cultured in either serum-free or serum-containing media. Bovine embryos cultured in serum-supplemented medium contain numerous cytoplasmic lipid droplets and immature mitochondria compared to those cultured in serum-free medium. The accumulation of cytoplasmic lipids in embryos developed in serum-containing medium may be a result of incorporation of lipoproteins from the serum and may result in impaired function of mitochondria. The improved serum-free media (IVMD101 and IVD101) offer several advantages over culture in serum-containing medium, including increased rates of blastocyst formation and higher cell numbers. Additionally, the survival and hatching rates of embryos produced in serum-free media after post-thaw culture were superior to those of embryos produced in the serum-containing medium, suggesting that the abnormal accumulation of cytoplasmic lipids in embryos may have a negative effect on the sensitivity of embryos to chilling and freezing. These serum-free culture systems have proven to be beneficial for the production of good quality embryos from IVM-IVF bovine oocytes. Furthermore, recent studies have shown a correlation between mitochondrial function (oxygen consumption) and embryo quality. A new method using scanning electrochemical microscopy may be capable of assessing the viability and developmental potential of bovine embryos.

Animals↗
PubMed2003

Single embryo transfer in IVF to prevent multiple pregnancies.

As the success rates of IVF clinics improve, one of the adverse consequences is the increased incidence of twins, due largely to the number of embryos transferred. Even if the number of embryos transferred is restricted to two, the twinning rate can exceed 40% of the pregnancies. An obvious way to reduce this high twin rate would be to transfer only one embryo. This would require that cryopreservation of the supernumerary embryos be efficacious enough so that the chance of achieving an ongoing pregnancy is not diminished by transferring a single embryo in the stimulated cycle. Previous studies utilising embryos on day 2 and 3 of development have shown that the pregnancy rates can be acceptable (about 40%) and that the cumulative rate can be up to 60%. Most of these studies, however, do not include a comparison with the cumulative pregnancy rate with two embryos transferred in the stimulated cycle. Therefore, the efficacy has not been proven. We present clinical data from the past few years to illustrate the increase in success rates and the concomitant increase in twinning rates. The increased success in the cryopreservation program has enabled us to trial a single embryo transfer program and compare the results to the transfer of two embryos. The results strongly suggest that the transfer of a single embryo is the better clinical option.

Embryo Transfer↗
PubMed1997

Viability of transgenic rat embryos after freezing and thawing.

In-vivo viability of frozen-thawed embryos derived from transgenic rats, as well as the transmission and the expression of transgenes in the resultant newborn rats, was investigated. Three strains of transgenic rats, carrying human growth hormone gene connected downstream to the promoter region of the bovine alpha-lactalbumin gene (alpha LA/hGH), bovine beta-casein gene (beta CN/hGH) or bovine alpha-S1 casein gene (alpha S1CN/hGH), were used. Two-cell stage embryos (non-transgenic Wistar female x heterozygous transgenic male) were placed in 10% (v/v) dimethylsulfoxide (DMSO) solution and cooled from -7 to -30 degrees C at -0.5 degree C/min before being plunged into liquid nitrogen. After 2 to 4 years storage, the embryos were thawed by rapid warming. The intact embryos were transferred into the oviducts of Day 1 pseudopregnant recipients. The postthaw survival rate of frozen embryos was high in all 3 transgenic strains (88 to 92%), which was similar to that of control (non-transgenic) frozen embryos (95%). Development to newborn rats following transfer of embryos derived from the 3 strains (64 to 68%) was also similar to that of control embryos (60%). These transgenes (alpha LA/hGH, beta CN/hGH and alpha S1CN/hGH) were detected in the DNA extracts from tail tissue of the newborn rats, but the transmission rates (41, 23 and 32%, respectively) were lower than 50% which is expected in the Mendelian fashion. In a transgenic line carrying alpha S1CN/hGH, hGH levels of secretion into the milk of transgenic newborn rats derived from frozen-thawed embryos and her transgenic offspring were the same mg/ml-level as that of their founder rat. Two-step freezing of embryos derived from transgenic rats was therefore an effective method for the long-term cryopreservation of transgene.

Animals↗
PubMed1995

[Fate of two different stages of embryos transferred to an identical recipient in mice].

To define the developmental fate of two different stages of embryos existing together in the mouse reproductive tract, different stages of fresh and frozen-thawed embryos were transferred separately into the oviducts of identical recipients. ICR and FvB embryos were flushed from the oviducts and/or uterus of superovulated females on Day 1 (2-4-cell stage) and Day 2 (8-cell-morula stage) of pregnancy. Day 1 embryos were transferred separately to the right or left oviduct of recipients, while the other oviduct received Day 2 embryos. There were no significant differences between Day 1 and Day 2 embryos with respect to the number of implantation sites and live fetuses in either the fresh or frozen-thawed embryos. These results concerning to the embryonic stage were similar to those of control experiments, in which Day 1 or Day 2 embryos were transferred to both right and left oviducts of recipients. Furthermore, no strain differences were observed in this study. No developmental retardation or anomalies were observed in fetuses derived from either Day 1 or Day 2 embryos. The embryo transfer in this study revealed that differences in developmental stage at preimplantation were synchronized by the maternal uterine environment.

Animals↗
PubMed2001

Studies on factors affecting superovulation and embryo transfer in Hungarian merino ewes.

The objectives of this study were (a) to assess the ovulatory response and embryo production of Hungarian Merino ewes after superovulation, (b) to investigate the factors influencing the efficiency of embryo transfer (ET) in Hungarian Merino ewes, (c) to compare the results of two ovarian stimulation protocols (PMSG and PMSG + FSH treatment) in Hungarian Merino ewes, and (d) to study how superovulation, laparoscopic insemination and surgical embryo retrieval (ER) affect the subsequent reproduction of Hungarian Merino donor females after an ET programme. There was no significant difference between the ovarian stimulation protocols in the ratio of donor ewes responding to superovulation nor in the average number of corpora lutea. However, the number of transferable embryos recovered per donor ewe was higher in the PMSG + FSH group. The proportion of transferable embryos, unfertilized oocytes and degenerated embryos did not differ between the treatment protocols. The total pregnancy rate was 53.4% (179/335). Neither the developmental stage of the embryo nor the number of transferred embryos affect the implantation of embryos. However, the increased number of transferred embryos positively influenced the pregnancy rate. No difference was found in the pregnancy rate between synchronised and non-synchronised groups of recipients. Thirty-six out of 45 donor ewes (80%) became pregnant within one year after the ET programme, indicating that ovarian stimulation and surgical ER did not affect adversely their reproduction.

Animals↗
PubMed2002

A simplified biopsy method for precompacted mouse embryos: a technical report.

This article presents a new, simple and rapid embryo biopsy method. The blastomere for genetic analysis can be separated from a precompacted mouse embryo after a partial zona digestion with the use of a holding pipette. For the micromanipulation only two microcapillaries and micromanipulators are needed. The development of the biopsied embryos was studied during in vitro culture and in utero following embryo transfer. There was no significant difference between the treated and the control groups in the ratio of embryos that developed to the blastocyst stage, although the biopsied embryos were delayed in their development because they contained significantly fewer cells compared to the control ones at the same stage. Although there was no difference in the ratio of implantation, the development of the biopsied embryos in utero was also delayed 12-24 hours on the 9th day of pregnancy. No difference in development was visible from the 13th day of pregnancy. Statistically, no differences were found in the developmental ratio (number of developed fetuses/transferred embryos) of the control and treated embryos during gastrulation (9th day of pregnancy), at the beginning of organogenesis (13th day of pregnancy) and before birth (19th day of pregnancy). The embryo biopsy method presented here can be a new and useful tool for preimplantation genetic diagnosis.

Animals↗
PubMedDate not supplied

Ultra rapid freezing and vitrification of human embryos derived from abnormally fertilised zygotes.

The present study was undertaken to compare the developmental capacity of human embryos derived from abnormally fertilised zygotes (1 PN, > 3 PN; 16-18 hours after ICSI) cryopreserved using two techniques: ultra rapid freezing and vitrification. At 2-4 cell stage, (48 hours after ICSI), these abnormally fertilised embryos were then distributed in three groups: a) embryos that were cryopreserved by ultra rapid freezing (URF Group), b) embryos cryopreserved by vitrification (V Group) and c) embryos that were not cryopreserved (Control group). Survival rates and embryo development after 24 hours of in vitro culture (72 hours after ICSI) were compared. 42 embryos were cryopreserved by ultra rapid freezing in 0.5 mL straws, using a mixture of dimethyl sulphoxide (3M) and sucrose (0.25M) in a base solution consisting of IVF medium plus 20 percent (v/v) of Human Serum Albumin (HSA), and 24 embryos were vitrified in 0.25 ml straws, using a two step protocol with an equilibration solution consisting of 10 percent ethylene glycol (1.79 M) and 10 percent dimethyl sulphoxide (1.41 M) in a base solution of modified phosphate buffered saline (PBS) with 20 percent of HSA and a vitrification solution consisting of 20 percent ethylene glycol (3.58 M), 20 percent dimethyl sulphoxide (2.82 M) and 0.5 M sucrose in base solution. The recovery rate after thawing/warming was lower for the vitrification group (75 percent V; 83 percent URF). The number of embryos with less than 50 percent of intact blastomeres after cryopreservation was significantly higher for the URF group (0 percent V; 34 percent URF). After in vitro culture, the rate of embryos not cryopreserved (Control group) that developed in vitro (72 hours after ICSI) was the highest (86 percent), followed by group V (50 percent), while group URF was the lowest (13 percent). These differences were statistically significant. This straw method of vitrification is successful and safe.

Blastomeres↗
PubMed1991

Production of embryos by oocyte cytoplast-blastomere fusion in domestic animals.

Embryos of amphibians, sheep, cattle, pigs and rabbits have been multiplied by nuclear transfer. Successful nuclear transfer in these species has been accomplished by transfer of a blastomere from a late-stage embryo into an enucleated oocyte with large scale multiplication by repeating the procedure using blastomeres from the embryos produced from nuclear transfer. This allows the production of clonal lines which, when appropriately selected for performance in a given trait, can be reproduced to capture in the offspring expression of additive and non-additive inheritance. The efficiency of these procedures is high only for amphibian embryos for which as many as 1000 offspring can be made from a blastula- or gastrula-stage embryo and the process repeated 60-100 times with descendant embryos. In domestic animals the largest number of offspring from one embryo has been 8 calves. Embryos as late as the 64-cell stage in cattle and 120-cell blastocyst in sheep have been used successfully as donors of blastomeres. Recloning has also been done in cattle. Nuclear transfer potentially provides a mechanism for multiplication and production testing of clonal lines, a method for rapid genetic improvement and rapid propagation of a selected genotype. Unfortunately the present efficiencies of subsequent embryo development, pregnancy and embryo survival are less than normal. This paper reviews variables contributing to reduced efficiency and research to improve nuclear transfer.

Animals↗
PubMedDate not supplied

[Intracytoplasmic injection and embryo quality: comparison with conventional in vitro fertilization].

We report here the results of a study comparing the quality of the embryos obtained after conventional IVF and after ICSI (respectively 872 and 459 embryos for 184 and 108 cycles). In the ICSI group, the female age was lower than in the IVF group, the oestradiol level on the day of hCG injection was higher, so that the number of retrieved oocytes and the number of mature oocytes. The policy of transfer being the same in the two groups, the mean number of transferred embryos was identical. The percentage of embryos without anucleate fragments, the percentage of embryos without irregularities, the percentage of 1, 2, 3, 4 or 5-cell embryos and the distribution of embryos in the 5 embryo scores were similar. In both IVF and ICSI groups, the transfer score (sum of the embryo scores of each transferred embryo) was higher for the patients who achieved pregnancy.

Adult↗
PubMed1995

Extracellular matrix interactions in early human embryos: implications for normal implantation events.

OBJECTIVE: To study the role of the extracellular matrix (ECM) proteins in supporting the development and implantation competence of human embryos. DESIGN: Expression of an implantation site adhesive glycoprotein, oncofetal fibronectin, and basement membrane collagen-degrading matrix metalloproteinase-2 and -9 were studied in cultured human embryos. The ability of exogenously added laminin and fibronectin to enhance hatching and matrix metalloproteinase-2 expression was quantitated also. PATIENTS: Fifty-four women with tubal factor infertility enrolled in the IVF program at the University Hospital of Oulu agreed to participate by providing 20 residual oocytes and 227 residual early embryos for this study. MAIN OUTCOME MEASURES: The presence of oncofetal fibronectin immunoreactive protein was assayed by immunocytochemical staining with two specific monoclonal antibodies, FDC-6 and X18A4. These antibodies bind to specific and distinct epitopes within tumor and trophoblast-derived oncofetal fibronectin. Changes in embryo matrix metalloproteinase-2 production were measured by zymography and confirmed by immunocytochemical staining. RESULTS: Intracellular oncofetal fibronectin was identified within blastomeres of early stage embryos. The immunoreactivity of oncofetal fibronectin in the zona pellucida was associated with fragmentation and dissolution of the zona. Exogenously added laminin or adult-type fibronectin significantly increased the hatching rate of the cultured embryos. Embryos cultured with added adult-type fibronectin or trophoblast-derived oncofetal fibronectin stimulated the matrix metalloproteinase-2 production (72-kd type IV collagenase) by 2.25 +/- 0.16-fold when compared with control embryos (mean +/- SD). CONCLUSIONS: Embryonic production of specific ECM proteins, such as oncofetal fibronectin, appears to be important for the morphological and biochemical development of human preimplantation embryos. Moreover, ECM proteins promote acquisition of the adhesive and degradative properties required by human embryos for successful implantation.

Adult↗
PubMed1994

Cryopreservation of supernumerary multicellular human embryos obtained after intracytoplasmic sperm injection.

OBJECTIVE: To investigate the pregnancy rate of frozen-thawed human supernumerary multicellular embryos that were cryopreserved after intracytoplasmic sperm injection or IVF. DESIGN: A clinical study. SETTING: Consenting patients in an academic research environment. PATIENTS: Couples with severe male infertility, indicated by failed or sporadic fertilization after IVF or subzonal insemination or by < 500,000 progressively motile spermatozoa in the entire ejaculate, and couples for IVF during the same period. INTERVENTIONS: After microinjection or IVF, the three best-quality embryos were transferred, and 1,171 embryos from intracytoplasmic sperm injection compared with 2,495 embryos from IVF were frozen with dimethyl sulphoxide. Of these, 413 and 969 embryos were thawed, respectively. MAIN OUTCOME MEASURE: The survival rate, the total and clinical pregnancy rates, the delivery rate, and the preclinical abortion rate were calculated. RESULTS: Fifty-three percent of the thawed intracytoplasmic sperm injection embryos survived. Twenty-two pregnancies have been established in 101 transfers, corresponding to a total pregnancy rate of 21.8% per transfer. The clinical pregnancy rate was 12.9% per transfer and the delivery rate was 5.9% per transfer. Of the IVF embryos, 51% survived and 37 pregnancies have been established in 253 transfers. The total and clinical pregnancy rates and the delivery rate were 14.6%, 10.7%, and 7.1%, respectively. The preclinical abortion rate was 40.9% for cryopreserved intracytoplasmic sperm injection embryos and 27.0% for IVF embryos. CONCLUSIONS: The high incidence of preclinical abortions after transfer of human embryos cryopreserved after intracytoplasmic sperm injection requires extension of the series.

Abortion, Spontaneous↗
PubMed1998

Rat embryos cultured under copper-deficient conditions develop abnormally and are characterized by an impaired oxidant defense system.

Rat embryos (gestation days 9.0 and 10.0) obtained from dams that were fed a Cu-adequate (8 micrograms Cu/g) or Cu-deficient (< 0.5 micrograms Cu/g diet were cultured for 48 hr in Cu-adequate (16.2 microM) or Cu-deficient (1.0 microM) rat serum. Control embryos cultured in control serum were morphologically normal. Embryos from Cu-deficient dams developed abnormally when cultured in Cu-deficient serum; the abnormalities included distended hindbrains, blisters, blood pooling, and cardiac defects. Control embryos cultured in Cu-deficient serum and Cu-deficient embryos cultured in control serum also showed abnormal development, but to a lesser degree than that of the Cu-deficient embryos cultured in Cu-deficient serum. To test the idea that the above abnormalities were due in part to free radical induced damage occurring secondary to an impaired oxidant defense system, a chemiluminescence assay was used to detect superoxide dismutase (SOD) activity in the cultured embryos. SOD activity was lowest in embryos cultured in Cu-deficient serum. When the Cu-deficient serum was supplemented with antioxidants (CuZnSOD or glutathione peroxidase), its teratogenicity was reduced. These data support the idea that an impaired oxidant defense system contributes to the dysmorphology associated with Cu deficiency. However, the Cu-deficient embryos also had low cytochrome c oxidase activity compared to control embryos--thus, multiple factors are likely contributing to Cu deficiency-induced abnormalities.

Adenosine Triphosphate↗
PubMed1997

Transition from maternal to embryonic control of development in IVM/IVF domestic cat embryos.

The timing of the transition from maternal to zygotic control of development (MZT) and the initiation of transcription was studied in domestic cat embryos to determine if there is a temporal association between these phenomena and the development block observed in cat embryos fertilized in vitro. Embryos were derived from in vitro-matured, in vitro-fertilized (IVM/IVF) oocytes. In Experiment 1, embryos (n = 52) were cultured continuously in the presence of 10 micrograms/ml alpha-amanitin (a transcriptional inhibitor) from 12-hr postinsemination (hpi), and cleavage stage was evaluated every 24 hr. The proportion of embryos cleaving to at least the 5-8 cell stage in the presence of alpha-amanitin (32/52) was similar (P > 0.05) to that of controls cultured without alpha-amanitin (25/50). In contrast, only 7.7% of alpha-amanitin-treated embryos cleaved to the 9-16-cell stage, compared with 38.0% of the controls (P < 0.05), indicating that products of embryonic transcription were required for cleavage beyond the 5-8-cell stage. In Experiment 2, embryos were cultured in the presence of 20 microM 3H-uridine for 12 hr beginning at 24, 36, 48, or 60 hpi and subjected to autoradiography. Embryos of 5-8-cell and 9-16-cell stages (14 of 27 and 8 of 12, respectively) clearly demonstrated nuclear labeling, a finding also confirmed by computer-aided densitometry. It is concluded that embryonic transcription and the MZT occur by the 5-8-cell stage of IVM/IVF domestic cat embryo development and the MZT is not directly related to the partial morula-to-blastocyst developmental block observed in cultured IVF cat embryos.

Amanitins↗
PubMed1999

In vitro development and nutrient uptake by embryos derived from oocytes of pre-pubertal and adult cows.

The present study compared the developmental potential and uptake of nutrients by embryos from pre-pubertal and adult cows. Oocytes retrieved from ovaries of 5 to 7 month old calves and adult cows were matured and fertilized in vitro. Embryos were cultured in SOFaa to the blastocyst stage (7 days post-insemination). At successive stages of development, rates of glucose and pyruvate uptake were measured non-invasively by microfluorescence for individual embryos. Fertilization was equivalent in embryos from pre-pubertal and adult cows (P > 0.05), however development to blastocyst was significantly lower in embryos from pre-pubertal cows (9.8% versus 33.7%, respectively; P < 0.05). Total blastocyst cell number was not different between pre-pubertal and adult material (P > 0.05). Glucose uptake was exponential (pre-pubertal, r = 0.82; adult, r = 0. 82; P < 0.05), with an increase in uptake beyond the 8- to 16-cell stage. Glucose uptake was significantly lower in embryos from pre-pubertal cows at the 2- to 4-cell stages (1.5 versus 3.0 pmoles/embryo/hr; P < 0.05), but was equivalent to the adult cow at all other stages of development (P > 0.05). Pyruvate uptake was low until the blastocyst stage. Pyruvate uptake by embryos from pre-pubertal cows was significantly different to adult cows at the 1-cell stage (2.7 versus 4.6 pmoles/embryo/hr, respectively; P < 0. 05) and 2- to 4-cell stages (4.9 versus 3.6 pmoles/embryo/hr, respectively; P < 0.05). Pyruvate uptake was equivalent in the two groups in the later stages of development (P > 0.05). Perturbations in the uptake of nutrients by embryos from pre-pubertal cows were most likely due to the presence of a high proportion of developmentally incompetent embryos. Further, embryos from pre-pubertal cows that did develop to the blastocyst were as viable as blastocysts from adult cows with respect to nutrient uptakes and total cell number.

Animals↗
PubMed1999

Cell allocation and chromosomal complement of parthenogenetic and IVF bovine embryos.

Considerable concerns exist regarding the quality of parthenogenetically activated embryos in terms of sufficient numbers of cells comprising the inner cell mass (ICM) and trophectoderm (TE) and the ploidy. Therefore, these two parameters were used to assess the quality of embryos derived from parthenogenetic activation by using calcium ionophore A23187 (CaI) followed by either 6-dimethylaminopurine (6-DMAP, 3.5 hr or 6.5 hr) or cycloheximide (CHX) plus cytochalasin D (CD). The conventional in vitro (IVF) produced embryos served as a control. Double staining of the parthenogenetic blastocysts showed that the total cell number (TC) of embryos from the 6-DMAP 3.5 hr (87.0 +/- 5.3) and CHX+CD (79.0 +/- 6.1) groups was not different (P > 0.05), but was lower than that of control embryos (116.0 +/- 5.8, P < 0.001). The mean ratios of inner cell mass (ICM) and trophectoderm (TE) cells in the 6-DMAP 3.5 hr group (0.57 +/- 0.04) and the control IVF group (0.50 +/- 0. 02) did not differ significantly. Both were higher than those of the CHX+CD group (0.36 +/- 0.02; P < 0.05). Further analysis of chromosomal compositions of developing stage embryos at day four after IVF or parthenogenetic activation demonstrated that prolonged treatment with 6-DMAP for 6.5 hr resulted in a significantly lower percentage of diploid embryos and a significantly higher percentage of abnormal ploidy embryos compared to treatment with 6-DMAP for 3.5 hr or with CHX and IVF. In conclusion, parthenogenetic activation of bovine oocytes with CaI followed by 6-DMAP for 3.5 hr could produce better quality embryos in terms of total cell numbers, the number of cells allocated to the ICM, and the ploidy of embryos.

Adenine↗
PubMed1997

The effect of pulsed and sinusoidal magnetic fields on the morphology of developing chick embryos.

Several investigators have reported robust, statistically significant results that indicate that weak (approximately 1 microT) magnetic fields (MFs) increase the rate of morphological abnormalities in chick embryos. However, other investigators have reported that weak MFs do not appear to affect embryo morphology at all. We present the results of experiments conducted over five years in five distinct campaigns spanning several months each. In four of the campaigns, exposure was to a pulsed magnetic field (PMF); and in the final campaign, exposure was to a 60 Hz sinusoidal magnetic field (MF). A total of over 2500 White Leghorn chick embryos were examined. When the results of the campaigns were analyzed separately, a range of responses was observed. Four campaigns (three PMF campaigns and one 60 Hz campaign) exhibited statistically significant increases (P > or = 0.01), ranging from 2-fold to 7-fold, in the abnormality rate in MF-exposed embryos. In the remaining PMF campaign, there was only a slight (roughly 50%), statistically insignificant (P = 0.2) increase in the abnormality rate due to MF exposure. When the morphological abnormality rate of all of the PMF-exposed embryos was compared to that of all of the corresponding control embryos, a statistically significant (P > or = .001) result was obtained, indicating that PMF exposure approximately doubled the abnormality rate. Like-wise, when the abnormality rate of the sinusoid-exposed embryos was compared to the corresponding control embryos, the abnormality rate was increased (approximately tripled). This robust result indicates that weak EMFs can induce morphological abnormalities in developing chick embryos. We have attempted to analyze some of the confounding factors that may have contributed to the lack of response in one of the campaigns. The genetic composition of the breeding stock was altered by the breeder before the start of the nonresponding campaign. We hypothesize that the genetic composition of the breeding stock determines the susceptibility of any given flock to EMF-induced abnormalities and therefore could represent a confounding factor in studies of EMF-induced bioeffects in chick embryos.

Abnormalities, Radiation-Induced↗
PubMed1995

Altered mitochondrial morphology of rat embryos in diabetic pregnancy.

BACKGROUND: Previous studies in vivo and in vitro have suggested that the oxidative metabolism of the embryo may have a role in the teratogenicity of diabetic pregnancy. In particular, the production of reactive oxygen species by the embryonic mitochondria has been implicated in the teratological process. The induction of congenital malformations by the diabetic milieu occurs during the early embryonic development. The present study aimed to estimate the role of the embryonic mitochondria in the teratological process of diabetic pregnancy by studying mitochondrial morphology in the embryos exposed to a diabetic environment in vivo or in vitro during early organogenesis and late fetal development. METHODS: For studies in vivo embryos of control or streptozotocin-diabetic rats were taken at gestational days 9-11 and subjected to light and electron microscopical analysis. The brain, heart, and liver of day-15 fetuses were also observed. For studies in vitro day-9 embryos of normal rats were cultured in a whole-embryo culture system for 48 hours. The culture media were supplied with high concentration of diabetes-related substrates and metabolites, and their effect on structure of embryonic neuroepithelial cells determined. RESULTS: The light microscopical observations demonstrated numerous cytoplasmic vacuoles in the ectoderm of day-9 embryos and in the neuroepithelium and blood cells of day-10 and day-11 embryos of diabetic rats. Ultrastructurally, these vacuoles were found to be mitochondria undergoing large-amplitude swelling with loss of matrix density and disturbed cristae. In contrast, no mitochondrial differences were found in the brain, heart, and liver, when day-15 fetuses from normal and diabetic rats were compared. Ultrastructural analysis of day-9 embryos cultured for 48 hours in the presence of high concentrations of D-glucose, pyruvate, beta-hydroxybutyrate, and alpha-ketoisocaproate also showed high-amplitude mitochondrial swelling in the neuroepithelium. The mitochondrial swelling was, however, not found in embryos cultured in a high concentration of L-glucose, excluding simple osmotic effects of the diabetes-related substrates and metabolites. CONCLUSIONS: The mitochondrial morphological changes appeared in embryos subjected to a diabetic environment during a time period when the congenital malformations in diabetic pregnancy are induced. The results support the notion that embryonic mitochondria are involved in the teratological process of diabetic pregnancy.

Animals↗