Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Embryos”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2Linked to original sources
PubMed1978

Measurement of metabolites in single preimplantation embryos; a new means to study metabolic control in early embryos.

Methods are described for preparing and analyzing single preimplantation mouse embryos for a variety of metabolites and cofactors (glucose-6-P, fructose-6-P, fructose-1,6-bisphosphate, ATP, AMP, Pi, citrate, isocitrate, alpha-ketoglutarate, and malate). Oil-well and enzymatic cycling techniques are combined to provide the sensitivity needed to measure the amounts present (10(-12) to 1o(-15) moles). After experimental treatment, embryos are collected on glass slides and freeze-dried. They can then be stored indefinitely under vacuum at -25 degrees C without deterioration. With these procedures, the embryos were collected at successive stages of development and subjected to starvation and refeeding with glucose, pyruvate or both. The results confirm the existence of a block at early stages at the P-fructokinase step. This may be due to inhibition by the very high citrate levels present. The data suggest that glycolysis is turned on late in preimplantation development by the rise in fructose-6-P, a deinhibitor of P-fructokinase. In the citrate cycle, no step between citrate and alpha-ketoglutarate is rate-limiting, but a step between alpha-ketaglutarate and malate appears to impede the flux at early embryonic stages.

Adenosine Monophosphate↗
PubMed1977

Pre-implantation embryos of Chinese hamster. I. Incidence of karyotype anomalies in 226 control embryos.

Karyotyes were determined in 226 pre-implantation embryos (4--8-cell stages) of Chinese hamster. The study was carried out under controlled natural breeding conditions, without superovulation and with the embryos developing in their mothers. A total of 5.3% karyotypically abnormal embryos were found. Over half, 3.1%, were due to ploidy mutations, 5 cases of triploidy and 2 cases of haploidy. Only 0.9% genome mutations were present, consisting of one autosomal trisomy and one autosomal monosomy. Structural aberrations were found in 1.8%, half of these probably due to a balanced maternal aberration and the rest appearing the mosaic condition only. These results are compared with the scarce body of mammalian data from the literature. Compared with the situation in man, the spontaneous aberration rates in the Chinese hamster and other experimental mammals are extremely low. This may be due, in part, to optimal timing of copulation in respect to estrus and ovulation prevailing in these animals but not in man. The low spontaneous aberration rate in the reported system is a valuable asset for purposes of mutagen testing.

Animals↗
PubMed1977

Wheat embryo ribonucleates. VII. Rapid, efficient and selective formation of 5S-18S and 5.8S-26S hybrids in an aqueous solution of the four ribosomal polynucleotides, and the results of a search for the corresponding hybrids in wheat embryo ribosomes.

(1) If wheat embryo 5S and 5.8S rRNA are differentially labelled, it can be shown that there is highly selective association of 5S [14C]RNA with 18S rRNA, and of 5.8S [3H]RNA with 26S rRNA when a solution (0.3 M NaCl) that contains approximately equimolar amounts of the four ribosomal polynucleotides is heated briefly (3 min) at 60 degrees C. (2) Comparison of Tm values and melting profiles for laboratory-prepared and natural 5.8S-26S rRNA hybrids suggests that restoration of the natural union between 5.8S and 26 rRNA can be achieved with facility and fidelity in the laboratory. (3) Union between 5.8S rRNA remains intact when wheat embryo ribosomes are disintegrated either by digestion with pronase or by treatment with sodium dodecyl sulphate, but the same treatments release 5S and 18S rRNA as freely migrating electrophoretic components. (4) Intact 18S and 26S rRNA can be prepared from small and large subunits, respectively, when wheat embryo ribosomes are dissociated by treatment with 0.5 M KCl. (5) Incidental to the principal investigation, it has been shown that, even after storage for more than 6 years at -70 degrees C, commercial supplies of roller-milled wheat germ yield S23 extracts that are very active in the cell-free translation of globin mRNA. (6) The physicochemical and possible biochemical significance of various types of intermolecular complexing between pairs of ribosomal polynucleotides is a subject of discussion.

Molecular Weight↗
PubMed1977

Wheat embryo ribonucleates. VIII. The presence of 7-methylguanosine 'cap structures' in the RNA of imbibing wheat embryos.

1. By imbibing wheat embryos in media that contain methyl-labelled methionine, it is possible to label both terminal and nonterminal 7-methylguanosine constituents in NaCl-insoluble (2.5 M, 0 degrees C) RNA (iRNA). 2. Most of the 7-[Me-14C]methylguanosine in wheat embryo i[Me-14C]RNA is present in nonterminal positions of polynucleotide chains, probably in ribosomal RNA. 3. By passage through a column of oligo-dT-cellulose, it is possible, to show that most of the 7-[Me-3H]methylguanosine in a 'bound' fraction of i[Me-3]RNA from imbibing wheat embryos is present in terminal 'cap' structures, probably in messenger RNA. 4. Although most of the 7-[Me-3H]methylguanosine in the 'unbound' (to oligo-dT-cellulose) fraction of i[Me-3H]RNA was present in nonterminal positions, there was also a highly significant fraction of 7-[Me-3H]methylguanosine in terminal 'cap' structures. Although it will be a subject of continued investigation, possible reasons why a large fraction of the total 7-[Me-3H]-methylguanosine was present in the 'unbound' fraction, in this present study, are a subject of discussion. 5. Careful analysis failed to reveal the presence of any N6,O2'-di[Me-3H]methyladenosine in the 'unbound' fraction of i[Me-3H]RNA. 6. Factors that might influence the binding of 'cap' oligonucleotides to DEAE-cellulose are the subject of a brief discussion.

Base Sequence↗
PubMed1979

Wheat embryo ribonucleates. XIV. Mass isolation of mRNA from wheat germ and comparison of its translational capacity with that of mRNA from imbibing wheat embryos.

Commercially milled wheat germ is shown to be a convenient source material for facile recovery of mass (milligram) quantities of highly purified poly(A)-rich RNA. This poly(A)-rich RNA is efficiently translated in a nuclease-treated extract of rabbit reticulocytes. By sucrose density gradient fractionation of bulk poly(A)-rich RNA from wheat germ, it has been possible to show that there is a direct relationship between the molecular weights of the polypeptide products of cell-free synthesis and the molecular weights of the wheat mRNA molecules which program their synthesis. As assessed by SDS -- polyacrylamide gel electrophoresis, the same array of polypeptides is synthesized when nuclease-treated reticulocyte extract is programmed by poly(A)-rich RNA from either commercially supplied or laboratory-prepared wheat embryos. Significantly, there are gross quantitative if not qualitative differences between the translational capacities of poly(A)-rich RNA from dry and imbibing wheat embryos, and the possible importance of these differences for interpreting a changing pattern of polypeptide synthesis in imbibing wheat embryos is the subject of a brief discussion.

Animals↗
PubMed1977

Cell transplantation into immunodeficient chicken embryos. Reconstituting capacity of cells from the yolk sac at different stages of development and from the liver, thymus, bursa of Fabricius, spleen and bone marrow of 15-day embryos.

Cyclophosphamide-treated 18-day-old chicken embryos were transplanted with histocompatible cells from the yolk sac at different stages of development and from the liver, thymus, bursa of Fabricius, spleen and bone marrow of 15-day-old-embryos. At the age of 36 days, the cell recipients were studied to determine the reconstitution capacity of the transplanted cells. The parameters used include the survival pattern, gain of body weight, antibody-forming capacity, response of peripheral blood lymphocytes to Con A, weight and microscopic morphology of the bursa of Fabricius, and weight of spleen and thymus. By all the criteria employed, only bursa cells were capable of a functional and morphological reconstitution of the recipient's humoral immune system. These data indicate that the role of the yolk sac as the first generator of prebursal stem cells remains questionable. In addition, these findings confirm the previous observations that, as a differentiation site of the B-cell lineage, the bursa of Fabricius precedes the bone marrow during ontogenetic development.

Animals↗
PubMed1979

The effects of experimental unilateral anotia on skull development in the chick embryo. V. The development of the brain and its meningeal envelope in embryos of 9-20 days of incubation.

In a total number of 27 normal and 27 unilaterally anotic chick embryos, varying in age from 9-19 days, the morphogenetic relationships between the neurocranium on the one hand and the brain and its meningeal envelope on the other were studied. The results showed that, in general, unilateral anotia slightly interferes with the development of the bain. Only the homolateral nucleus tangentialis and cerebellar auricle proved to be underdeveloped. However, the brain of the anotic embryos progressively develops asymmetrically: In an antero-posterior and a ventro-dorsal direction abnormal flexures are present, and various components of the brain on the anotic side undergo changes in shape and position. These changes in brain morphology are interpreted as secondary features. Hence, the conclusion is drawn that the neurocranium, through the intermediary of the meningeal envelope, controls--or at least is capable to control--the general morphological development of the brain.

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↗
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↗
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↗
PubMed1975

Wheat embryo ribonucleates. V. Generation of N2--dimethylguanylate when 'fully sequenced' homogeneous species of transfer RNA are used as substrates for wheat embryo methyltransferases.

When S-adenosly[methyl-14-C]methionine and various species of transfer RNA are used as substrates for wheat embryo methyltransferases, the principal site of guanylate-N-2 methylation can be shown to be a G-residue between the stems of the dihydrouridine and anticodon loops. This common site of guanylate-N-2 methylation is referred to as the interstem target site. 2. When the interstem target site is the non-terminal G-residue in a G-C-G-C sequence, as in the cases of Escherichia coli tRNA1-Leu, tRNA-Ile, and tRNA3-Ser, there is preponderant dimethylation to yield N-2-dimethylguanylate. 3. When the interstem target site is part of a U-C-G-U sequence, as in the case of E. coli tRNAf-Met, there is diminished dimethylation and correspondingly increased monomethylation to yield N-2-monomethylguanylate. 4. When the interstem target site is the non-terminal G-residue in an A-U-G-G sequence, as in the case of yeast tRNA-Asp, there is negligible dimethylation and almost exclusive monomethylation to yield N-2-monomethylguanylate. 5. The concerted way in which the primary, secondary, and tertiary structures of tRNA molecules might influence the efficacy of these methylations is the subject of a brief discussion. Attention is also focused on the evolutionary and molecular basis for the generally non-random distributions of methylated oligonucleotide sequences in ribosomal and transfer ribonucleates.

Base Sequence↗
PubMed1977

Fine-structural studies of the gametes and embryo of Fucus vesiculosus L. (Phaeophyta). III. Cytokinesis and the multicellular embryo.

Condensation of the chromosomes during the first cell division following fertilization of the brown alga Fucus vesiculosus L. is accompanied by the almost complete disappearance of the nuclear envelope. Golgi vesicles and other small vesicles appear within the spindle, which has paired centrioles at each end. A large amount of rough endoplasmic reticulum is in the surrounding cytoplasm during mitosis, and many vesicles at the spindle margin are encircled by stacks of endoplasmic reticulum. Annulate lamellae are observed during mitosis. The envelope which initially reforms around the chromatin in telophase has unevenly spaced nuclear pores. Cytokinesis results primarily by vesicle addition to a centripetal furrow. Mitochondria and chloroplasts concentrate around the partition site, possibly in association with microfilaments. Fibrillar material is added rapidly to the space between the daughter cells from vesicle discharge of both cells and seems to spread into the older cell wall surrounding the embryo. The rhizoid daughter cell contains numerous mitochondria and hypertrophied Golgi bodies whose vesicles increasingly pack the cell. The thallus daughter cell is packed with a variety of vesicles, and the nucleus is surrounded by many dilated cisternae of rough endoplasmic reticulum. By the four-cell stage, chloroplasts of the rhizoid cells have weakly staining lamellae, while chloroplasts of the thallus cells are actively dividing with deeply staining lamellae.

Cell Division↗
PubMed1975

Mouse embryo development in vitro: effects of inhibitors of RNA and protein synthesis on blastocyst and post-blastocyst embryos.

The effect of inhibitors of RNA synthesis (Cordycepin, Actinomycin D) and protein synthesis (Cycloheximide) on the development and growth of mouse blastocysts in vitro was explored. Blastocysts exposed in vitro for 24 hours to 50 mu-g/ml Cordycepin, 0.005 mu-g/ml Actinomycin D, or 0.1 mu-g/ml Cycloheximde grew and began to attach to the dish in the similar manner as did the controls. Cell number, 3-H-thymidine-labeling index and mitotic index in treated blastocysts were also similar to controls. Cell number, 3-H-thymidine-labeling index and mitotic index in treated blastocysts were also similar to controls. Control blastocysts grown in vitro for six days attached to the dish, trophoblastic layer was spread and inner cell mass continued to grow and formed an egg-cylinder like structure. Blastocysts grown in constant presence of 50 mu-g/ml of Cordycepin in themedium or those exposed to inhibitor only for the first 24 hours failed to develop inner cell mass derivatives in culture, although the growth of trophoblastic cells was as in controls. The same results were obtained if blastocysts were exposed to 0.005 mu-g/ml of Actinomycin D or to 0.1 mu-g/ml of Cycloheximide either continuously or for the first 24 hours. Higher concentrations of Actinomycin D (0.05 mu-g/ml) or Cycloheximde (1 mu-g/ml) were toxic for the blastocysts causing their degeneration within 24-48 hours. Our results suggested that appropriate concentrations of RNA or protein synthesis inhibitors could prevent the development of inner cell mass derivatives with essentially no effect on the development of primary trophoblast. This would indicate that the process of differentiation of inner cell mass cells is much more sensitive to metabolic inhibitors than the differentiation of giant trophoblastic cells.

Animals↗