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At least 577 records · Page 32Linked to original sources
PubMed1987

Cell transformation and promoter activity of insulation oils in the Syrian hamster embryo cell and in the C3H/10T1/2 mouse embryo fibroblast test systems.

The ability of mineral-oil-based and synthetic cable insulating fluids to transform and promote transformation of mammalian cells in vitro have been studied. In experiments with the Syrian hamster embryo cell transformation assay, it was found that C15-C18 alkylbenzenes were the most potent inducers of transformation, followed by low-viscosity and residual mineral oils. No activity and low cytotoxicity were found for a low-viscosity polyisobutylene-based oil. In the two-stage transformation assay of C3H/10T1/2 cells, promoter activity was obtained with all fluids tested. A blend of residual and low-viscosity mineral oils showed the highest activity. This oil possessed a low cytotoxicity and was tested at a relatively high concentration. The alkylbenzenes were more potent than the polyisobutylene-based fluid. The alkylbenzenes were also found to possess initiating activity in the two-stage assay, when 12-O-tetradecanoylphorbol 13-acetate (TPA) was used as promoter. All the fluids showed low potency compared to benzo[a]pyrene and the tumor promoter TPA.

Animals↗
PubMed2000

Embryo implantation and GnRH antagonists: GnRH antagonists in ART: lower embryo implantation?

Recently, concerns have been raised regarding possible adverse effects of gonadotrophin-releasing hormone (GnRH) antagonists on extra-pituitary reproductive cells and organs, i.e. ovarian cells, oocyte, embryo, endometrium. These concerns are based on numerous in-vitro studies suggesting decreased biosynthesis of growth factors caused by local action of GnRH antagonists. Clinically, it has been shown that the use of high doses (< or =1 mg daily) of GnRH antagonists is associated with low implantation rates in IVF. Although such direct adverse effect of GnRH antagonists cannot be ruled out at this time, so far clinical experience points to profound LH suppression as the major caveat associated with the use of high doses of GnRH antagonists. Very low LH concentrations are associated with aberrant concentrations of oestradiol during ovarian stimulation, which may in turn adversely effect implantation potential. The clinical data available thus far on the use of GnRH antagonists originate from protocols designed for clinical studies. It is predicted that as more clinical experience is gained, and with protocol modifications to suit individual patient response, GnRH antagonists will be comparable with the agonists in terms of cycle outcome.

Embryo Implantation↗
PubMed1999

In vitro production of sexed embryos for gender preselection: high-speed sorting of X-chromosome-bearing sperm to produce pigs after embryo transfer.

The objectives for the present experiments were to apply sperm sexing technology to an in vitro production system with porcine oocytes obtained from slaughterhouse material. On six experimental days, ovaries were obtained from an abattoir, and cumulus-oocyte-complexes were matured in vitro. Semen was collected from mature boars of proven fertility and was sorted for X-chromosome-bearing sperm, using the Beltsville Sperm Sexing Technology incorporating the use of high-speed sorting. A total of 5,378 oocytes were submitted for in vitro fertilization (IVF). Of these, 559 ova were stained for cytogenetic analysis 18 h after IVF. From the remaining 4,819 ova, 1,595 cleaved, and 1,300 of the cleaved embryos were transferred into 26 synchronized recipients (5 control gilts for unsorted sperm, 21 gilts for X-sorted sperm). In a test of two fertilization media (FERT-A vs FERT-B) higher cleavage rates (P<.05) were obtained when FERT-B was used as a fertilization medium for unsorted (43.4+/-5.1%) and sorted sperm (43.1+/-1.1%;), whereas in FERT-A unsorted sperm gave a cleavage rate of 17.9+/-4.4% and sorted sperm gave 30.4+/-1.4%. Additionally, cleavage rates were higher (P<.05) after fertilization with sorted sperm vs unsorted sperm, independent of fertilization medium. Cytogenetic analysis of ova revealed that more oocytes with unsorted than with sorted sperm remained in Metaphase 2 arrest (P<.05). This was also independent of the fertilization medium. Monospermic fertilization rates were the same for IVF with unsorted or sorted sperm, independent of the fertilization system, except FERT-A with unsorted sperm (P<.05). Polyspermic fertilization rates were highest in FERT-B (37.6+/-6.6). A total of 57 pigs were born from nine litters. Six litters from sexed sperm (X-sorted) produced 33 females (97%) and one male. Three litters from control transfers produced 23 pigs, 11 of which were female (48%). The sex ratio of the offspring was predicted based on the sort reanalysis of the sorted sperm for DNA content.

Animals↗
PubMed1976

[Growth of eye and orbit in chick embryo. IX. Developement of eye and skull origin in 3-9 day old embryos with experimental bilateral microphthalmia].

Chick embryos in which on the third day of incubation the lens of both eye primordia was removed, were sacrificed at the ages of 5,7 and 9 days and fixed in a 70 per cent alcohol solution. An analysis was made of the consequences of the absence of normal large eyes upon the structure and growth of the skull. Immediately after the operation no changes in the head mesenchyme could be observed, but during the next days, as growth goes on, abnormal proportions and dimensions develop in the anterior part of the skull. Generally, this part of the skull is depressed and shorter than normal; cartilages around the eye have a different position and smaller dimensions. A perfect symmetry is only rarely maintained. There seems to be a very labile balance in the skull, as may be deduced from the presence of a buckled interorbital septum and the deviation of the upper beak.

Animals↗
PubMed1976

The effects of experimental unilateral anotia on skull development in the chick embryo. III. Chondrocranial development in anotic embryos of 7-20 days of incubation.

The study of the development of of the chondrocranium in chick embryos with unilateral (right-sided) anotia revealed the following main characteristics. 1. The median axes of the chordal and the prechordal part of the cranial base are not in a straight line but show a deviation toward the right side. The angle between the two axes has its vertex in the region of the foramen hypophyseos. 2. The metotic cartilage and the foramina of the IXth and Xth cranial nerves are normal in position. 3. The tectum synoticum develops later and to a lesser extent than normal. 4. Between the basal plate, the metotic cartilage, the occipital arch and the supracapsular cartilage a foramen is formed which, later in development, is closed by outgrowths of the metotic cartilage and the basal plate. 5. The "optic area" shows a practically normal appearance which indicates that the cartilaginous ventral wall of the lagenal capsule is of basal plate origin. 6. The pro-otic process develops practically normal and, hence, is independent of the ear capsule. 7. The quadrate cartilage and the right lower jaw are displaced ventro-posteriorward. The earliest development of the perichondral bones shows some particularities which are closely correlated with the development of the various cartilaginous structures.

Animals↗
PubMed1992

Mock embryo transfer in early luteal phase, the cycle before in vitro fertilization and embryo transfer: a descriptive study.

OBJECTIVE: To investigate visually the uterine retention or sequestration of boluses of radiopaque dye, mimicking embryo transfer (ET). DESIGN: During the cycle before in vitro fertilization (IVF) and ET, patients underwent a mock ET of 40 microL of radiopaque dye into the uterine cavity. The patient was positioned supine for retroverted or axial and knee chest for anteverted uteri. The position of the dye at injection, during and after catheter removal, and during patient roll over and standing was monitored. SETTING: Treatment of infertility in a private practice. PATIENTS: Thirty-four IVF patients. INTERVENTIONS: During the cycle before IVF/ET, patients underwent a mock ET using a bolus of 40 microL of radiopaque dye. MAIN OUTCOME MEASURES: Planned before visual observation began. RESULTS: The dye remained primarily in the uterine cavity in only 68% (optimum ET position is knee chest for anteverted and supine for retroverted or axial uterus) and 48% (nonoptimum position is supine for anteverted uterus) at mock ET; in those groups, a 33% clinical pregnancy rate (PR) per retrieval resulted. Dye motility into the fallopian tube(s), cervix, and/or vagina is 38.2%, 8.8%, and 11.8%, respectively. CONCLUSIONS: If the mock ET had been the actual ET, 32% (optimum ET position) and 52% (nonoptimum ET position) of all patients would have lost their opportunity for pregnancy as a result of the ET procedure. Our 33% PR per retrieval among those patients who retained the dye in utero is more consistent with our expectations, given the advanced technologies of IVF/ET today.

Embryo Transfer↗
PubMed1991

[Crossed graft of embryonic testis between quail and chick embryos: contribution to the study of the mechanism of female bird embryo masculinization].

Quail, or chick embryonic testes grafted respectively in the extraembryonic coelom of chick or quail embryos induce both a Mullerian duct regression and a masculinization of the female host gonads up to the differentiation of two testes, in some cases. Such a result confirms the fact evidenced previously in other bird species (chick and duck) that the testis-inducer is interspecific. Quail cells are not observed in histological sections of embryonic gonads of testis-grafted chicks. This allows to discard a possible influence of cells migrating from the graft to the host. The grafted testes act then through substance/s secreted in the blood stream. Present and previous experimental data strongly suggest that the same substance, i.e. the so-called anti-Mullerian hormone, is responsible for both MD regression and gonadal sex reversal.

Animals↗
PubMed1989

[Effects of IPO-63, Carbaryl, Foschlor and Reglone on Newcastle disease virus replication in chick embryo and chick embryo cell cultures].

Cell cultures and chicken embryos were treated with maximum tolerant concentrations of different compounds and infected with Newcastle disease virus simultaneously or 24 hours after the compounds were introduced. The similar results were obtained in both cases. It was found that Reglone inhibited Carbaryl increased virus multiplication. The study on dynamics of virus multiplication indicates that only in the case of IPO and Carbaryl their stimulatory effect on virus at the final stage was preceded by its inhibition.

Animals↗
PubMed1987

Morphometric study of cartilage dynamics in the chick embryo tibia. I. Methodology and tissue compartments in normal embryos.

Cartilage dynamics during the development of the chick embryo tibia has been studied by means of morphometric methods, from the 11th to the 14th days. The volume densities of the structures enclosed by the perichondrium-periosteum did not change significantly through the age span studied, whereas the absolute volumes of these structures increased during the whole period under investigation. The cartilage volume showed the most rapid increase from Day 12 to Day 13 (by a factor of x1.74). The volume of the invading connective and vascular tissue increased rapidly from Day 11 to Day 14. The rate of cartilage formation decreased from 7.60 +/- 1.02 to 3.82 +/- 0.89 mm3/day (from Day 13 to Day 14), whereas the rate of cartilage resorption increased until Day 13 (by a factor of x2.71), reaching a plateau after this age. Although cartilage formation was higher than resorption during this period, the changes found by Day 13 indicate that shortly after this age cartilage resorption will predominate over cartilage formation, leading to the disappearance of the cartilaginous model.

Animals↗
PubMed1979

Production of erythropoietic colony-forming units and erythrocytes during chick embryo development: an attempt at modelization of chick embryo erythropoiesis.

The enumeration of erythropoietic colony-forming cells in vitro has allowed us to complete previous data on changes in the various erythroid cell populations during chick embryo-genesis. Erythrocytic colony-forming units in culture (CFU-cE) which are sensitive to avian erythropoietin appear in the blastoderm as soon as the 24th hour of development. They represent most likely precursors of the megalocytic erythropoiesis, and do not seem to derive from stem cells common with normocytic erythropoiesis. Data concerning vitelline normocytic erythropoiesis were analysed in a kinetic model based on stochastic change of the stem cells. From this model it appears that 17-20 cell divisions are required for differentiation of erythrocytes from stem cells.

Animals↗
PubMed1984

Actin organization in chick embryo fibroblasts after influenza virus infection. I. Isolation and characterization of actin from chick embryo cells.

Comparison of two starting materials for actin purification has shown that preparation of actin from aceton-dried cytoskeleton was more effective than from native chick embryos (CE). The isolated actin formed a single band of Mr = 42-43000 in SDS-PAGE; less purified samples revealed additional faint bands. G form of actin (non-polymerized) inhibited the activity of DNase I, electron microscopy showed actin filaments and bundles formed upon its polymerization. The freshly purified homogeneous actin has not lost its DNase I-inhibiting activity when incubated for 60 min at 35 degrees or 45 degrees C. Older or less purified actin samples kept under similar conditions showed 18-25% decrease of their DNase I-inhibiting activity and a loss of their polymerization ability. Digestion with trypsin caused a decrease of DNase I-inhibiting activity of fresh as well as for older actin samples.

Acetone↗
PubMed1980

Natural cytotoxicity in the mouse embryo. I. Evidence for the presence of natural cytotoxic function in the yolk sac of the 10-day mouse embryo.

Yolk sac cells from 10-day mouse embryos have natural cytotoxic activity directed against YAC-1 tumor targets but not against P815 tumor targets. Other embryonic tissues tested, including TG-16 embryonal carcinoma, fetal thymus, and fetal liver, do not display natural cytotoxic activity comparable to the yolk sac activity. The correlations between yolk sac natural cytotoxic function, and adult NK and promonocyte cytotoxic functions are briefly discussed.

Animals↗
PubMed1977

The effects of experimental unilateral anotia on skull development in the chick embryo. IV. Development of the bony skull in embryos of 9-20 days of incubation.

The study of the development of the bony skull in chick embryos with unilateral (right-sided) anotia revealed the following characteristics: 1. The perichondral bones initially follow exactly the cartilaginous structures to which they are related. Later, they may expand desmally to fill up the gaps and diminish the degree of pre-existing asymmetry. 2. The desmal bones which develop in close contact with cartilage, develop parallel to its margins and, hence, appear to be greatly dependent on the chondrocranium. 3. Among the desmal bones which arise independently from cartilage, only the bones of the cranial vault proved to be influenced by the unilaterally anotic condition.

Animals↗