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At least 55 records · Page 3Linked to original sources
PubMed1992

Ellagic acid protects rat embryos in culture from the embryotoxic effects of N-methyl-N-nitrosourea.

Ellagic acid is a naturally occurring plant phenol that has demonstrated anticarcinogenic and antimutagenic activity in several test systems. Given the common proposed etiopathogenic processes of mutagenesis, carcinogenesis, and teratogenesis induced by genotoxic chemicals, the present study was initiated to determine whether ellagic acid would protect rat embryos in culture from the teratogenic effects of N-methyl-N-nitrosourea (MNU). Ellagic acid alone (as used in these experiments; 50 microM in DMSO) was not embryotoxic. Ellagic acid (50 microM) significantly (P less than 0.01) prevented MNU (75 microM)-induced effects including mortality (absence of heart beat), abnormal formation of the cephalic neural tube derivatives, and delayed differentiation as assessed by a morphological scoring system. These embryoprotective effects were dose responsive. Sequential treatment of embryos with ellagic acid followed by MNU in fresh media also was embryoprotective with no diminution of effect. The site at which ellagic acid interrupts the critical teratogenic events induced by MNU is apparently within the embryo and/or placenta. This model of chemical embryoprotection may be useful in determining the role of cell death and/or mutation in the teratogenic mechanism of action of methylating agents.

Abnormalities, Drug-Induced↗
PubMed1992

Genetic differences in heat-induced tolerance to cadmium in cultured mouse embryos are not correlated with changes in a 68-kD heat shock protein.

Heat-induced cross-tolerance to cadmium was investigated in two inbred strains of mice, BALB/c and SWV, using a whole embryo culture system. Embryos were exposed to a pretreatment of 5 min at 43 degrees C and subsequently to an embryotoxic concentration of cadmium, 1.75 microM. The two types of embryos responded differently to the heat pretreatment, as cross-tolerance was induced in SWV but not in BALB/c mice. In SWV embryos, prior exposure to 43 degrees C for 5 min essentially eliminated the negative effects of cadmium on embryonic development and growth. However, in BALB/c embryos, no protection was observed. The variation in development of cross-tolerance in embryos from the two strains of mice was not correlated with differences in the induction of a 68-kD heat-shock protein (hsp68). There was a rapid increase in this protein in both strains after the initial heat exposure but not excess induction in the SWV strain that developed tolerance. The induction of hsp68 is therefore not sufficient to elicit cross-tolerance, and other mechanisms are likely to be important in the protective response of the embryo.

Animals↗
PubMed1996

Osteogenic protein-1 is required for mammalian eye development.

Osteogenic Protein-1 (OP-1/BMP-7) is a bone morphogenetic protein in the transforming growth factor-beta superfamily and has been shown to be expressed temporally and spatially during epithelial-mesenchymal interactions mediating tissue morphogenesis in early embryogenesis. In order to identify the primary role(s) for OP-1 in development, we carried out whole rat embryo cultures, over a 72-h period from primitive streak stages to early limb bud stages, in rat sera containing either OP-1 blocking antibodies (10 micrograms/ml) or nonreactive IgG. Rat embryos cultured with control antibodies developed normally, while those cultured with anti-OP-1 antibodies consistently exhibited over-all reduced size and absence of eyes. Histological sections revealed a greater reduction in neural retina development in the embryos treated with anti-OP-1 blocking antibodies. In situ hybridization and immunolocalization analyses indicate that OP-1 is expressed in the neuroepithelium of the optic vesicle at E11.5, is limited to the presumptive neural retina and developing lens placode, and is subsequently expressed in the neural retina, lens and developing cornea at E12.5-E13.5. Our results indicate that OP-1 mediates the inductive signals involved in mammalian eye development.

Animals↗
PubMed1996

Positional determination of the naso-temporal retinal axis coincides with asymmetric expression of proteins along the anterior-posterior axis of the eye primordium.

We used two different methodologies to examine at what stage development retinal positional specificity is established and which molecules are responsible. The first goal was achieved by removing parts of the presumptive temporal primary optic vesicle at stage 11 (40 to 45 hr of incubation) and fate mapping of tissue with presumptive nasal properties that shifted into the wound during the events of wound-healing. Participation of the shifted tissue in the healing resulted in assembly of a temporal retina with mosaic-like projection properties, as examined by retrograde double staining of the retinal ganglion cells from the optic tectum. In addition to cells with normal temporal-rostral projections, clusters of ganglion cells with nasal-like projection identities appeared labelled within the temporal hemiretina. The number of clusters increased with the amount of resected tissue, and by almost complete ablation of the presumptive temporal anlage, a temporal hemiretina with predominantly nasal retinotectal specificity was created. These neuroanatomical results suggested that neuroepithelial cells had fixed nasal and temporal positional specificities at stage 11. To examine differences in the cells derived of either half of the eye cup, we performed biochemical one- and two-dimensional gel electrophoresis of the hemianlagen at stage 11. In addition, incorporation of 35S-methionin into newly synthesized peptides was investigated. Both techniques revealed the exclusive expression of one major and three less-abundant proteins within the presumptive nasal anlage. The most abundant of these proteins has a molecular weight of about 40 kDa and is clearly distinguishable both in gel electrophoresis and autoradiography. The asymmetric protein patterns had disappeared when the retina was analysed with the same methods at the more advanced embryonic days E4 and E6. The asymmetry in the expression of proteins in the retinal primordium may be the biochemical correlate of an early positional specification of the retinal neuroepithelium. The difference in the protein expression may explain that mixing the positionally specified cells of either origins results in projection mosaics.

Animals↗
PubMed1978

Expression of lactate dehydrogenase isozyme 5 (LDH-5) in cultured mouse blastocysts in the absence of implantation and outgrowth.

Extensive extraction studies with Triton X-100 revealed only LDH-1 (B4) but no trace of LDH-5 (A4) in one-cell and two-cell mouse and rat embryos. The LDH isozyme pattern of preimplantation mouse embryos changes from the maternally inherited B subunit isozyme (LDH-1) to a pattern dominated by LDH-5 when mouse blastocysts are cultured under conditions that prevent hatching but allow trophoblast giant cell transformation. During differentiation of mouse blastocysts in vitro, implantation is therefore not essential for the appearance of the A subunit form of LDH (LDH-5) coded for by the embryonic genome. Mechanisms controlling the expression of LDH-5 in mouse blastocysts during in vivo development are discussed.

Animals↗
PubMed1976

Plating efficiency of mouse embryo cells as a function of gestational age.

Mouse embryo cells can be plated directly from single-cell suspensions of fresh embryos. For randomly bred Swiss mice, there is an increase in plating efficiency as a function of gestational age. Colony-forming units appear at about day 10 and there is an exponential increase in colony-forming ability up to day 16, after which there is no further increase.

Animals↗
PubMed1985

Effects of beta-hydroxybutyrate on rat embryos grown in culture.

In order to investigate further the relationship between maternal diabetes and fetal malformation, rat embryos were grown in vitro in the presence of beta-hydroxybutyrate, one of the ketone bodies produced by diabetics. At 10 mM, beta-hydroxybutyrate produced minor abnormalities and at 20 mM it produced major abnormalities in rat embryos.

Abnormalities, Drug-Induced↗
PubMed1988

A minichamber device for maintaining a constant carbon dioxide in air atmosphere during prolonged culture of cells on the stage of an inverted microscope.

Construction details are described for a minichamber device that maintains a localized atmosphere of carbon dioxide in air over the stage of an inverted microscope. This device is easily constructed from Plexiglas and its specifications can be adjusted to fit virtually any inverted microscope. A flow of warm, humidified carbon dioxide in air gas mixture can be directed over a petri dish or unsealed culture flask to maintain the pH of bicarbonate-CO2 buffered media. By this means, prolonged culture of cells directly on the microscope stage is made possible without occurrence of detrimental pH changes. If the microscope is fitted with an environmental control chamber to maintain temperature, cells can be maintained on the microscope stage for days, permitting frequent observation of cell growth and activity. Alternatively, continuous cine or video recordings can be made. For example, using this device, hamster and rhesus monkey embryos have been cultured for 2 to 5 d on an inverted microscope while continuous time-lapse recordings were made of cell division and differentiation and activity of cellular organelles.

Animals↗
PubMed1990

Co-culture of two-cell rat embryos on cell monolayers.

Monolayers of 2 different populations of uterine cells and of fetal fibroblasts were evaluated for the support of rat embryo development in vitro. Compared to controls, cultures performed in Earle's buffered saline solution (EBSS) alone, the cleavage rate of 2-cell embryos to the 4-cell stage was significantly increased when the embryos were cocultured for 24 h with mixed uterine stromal and myometrial cells (70.7 vs. 56.0%; P less than 0.01). Coculture of 2-cell embryos with either uterine epithelial-stromal or stromal-myometrial cells in medium TC 199 (M199) for 24 h significantly increased the cleavage rate to the 4-cell stage compared to controls in the same medium (respectively, 78.3 and 77.6 vs. 49.9%; P less than 0.01). The development was not improved when fibroblasts were used as feeder cells. After 48 h, the proportion of 4-cell embryos showing cellular fragmentation was significantly decreased in the presence of either epithelial-stromal or stromal-myometrial cells in M199 compared to controls (respectively, 18.4 and 20.0 vs. 43.8%; P less than 0.01). Coculture in EBSS or with fibroblasts failed to prevent embryo degeneration. In one coculture with stromal-epithelial cells in M199, 6/11 embryos proceeded beyond the 4-cell stage, two of them reaching the 8-cell stage. No embryo developed beyond that stage in our study. Although considerable efforts remain necessary to achieve further growth, these results suggest that coculture offers promise as a means of supporting the in vitro development of rat embryos.

Animals↗