bluuebunny/crossref_metadata_2025_split huggingface dataset:
Postimplantation development of CB-induced triploid mouse embryos
Authors: Niemierko Anna 
Published: April 2021

ABSTRACTBy subjecting A strain eggs at the time of fertilization and polar body extrusion to 5 μg/ml cytochalasin B, digynic triploidy was produced in 80 % fertilized eggs. Triplonucleate eggs were transplanted to recipients and examined between 9–11th day of pregnancy. Development of triploid mouse embryos up to day 7 is normal and most embryos form early egg cylinder. At day 8 the embryonic part of the cylinders is under-developed and later development fails to form an embryo. Development of foetal membranes is much less affected, CB-induced triploids survive to 10th-day of pregnancy.
Time-lapse film analysis of cytoplasmic streaming during late oogenesis ofDrosophila
Authors: Gutzeit Herwig O. , Koppa Roswitha 
Published: April 2021

ABSTRACTCytoplasmic streaming in follicles of Drosophila has been analysed in vitro by means of time-lapse films. Late vitellogenic follicles develop normally in vitro as judged by morphological criteria. Furthermore, follicles (stage 10 and younger) which were cultured in vitro for the same length of time as follicles which were filmed, developed normally in vivo after injection into a host fly. The recorded cytoplasmic movements are, therefore, unlikely to be an in vitro artefact.At early vitellogenic stages (up to stage 9; King, 1970) no cytoplasmic streaming can be detected, but at stage 10A cytoplasmic movements are initiated within the oocyte. At stage 10B, when the nurse cells start degenerating, nurse cell cytoplasm can be seen to flow into the growing oocyte. At stage 11 a central stream of nurse-cell cytoplasm reaches the oocyte within a minute. The ooplasmic streaming is most rapid at stage 10B and stage 11 and only an oocyte cortex up to 7 μm thick remains stationary. Once the bulk of the nurse-cell cytoplasm has poured into the oocyte (stage 12) the cytoplasmic movement ceases, first in the nurse cells and later in the ooplasm. In mature oocytes no cytoplasmic streaming can be detected.
Preferential paternal X inactivation in extraembryonic tissues of early mouse embryos
Authors: Harper Mary I. , Fosten Mandy , Monk Marilyn 
Published: April 2021

ABSTRACTThe preferential expression of the maternal X chromosome seen in certain extraembryonic membranes of the mouse was studied by investigating the tissues from which these membranes are derived during early development. The electrophoretic variant of the X-coded enzyme PGK-1 (phosphoglycerate kinase) was used to distinguish the expression of the maternal from the paternal X chromosome in heterozygous females.Both the extraembryonic ectoderm and primary endoderm of -day female egg cylinders gave almost exclusive expression of the maternal form of the enzyme whereas the epiblast gave near equal expression of the two parental alleles. No paternal PGK-1 band could be detected in samples of pooled -day blastocysts, but after 3 or 4 days of culture in vitro a faint paternal band was seen in the resultant outgrowths. The activity of the maternal band in these latter samples had increased greatly from that of the blastocysts, consistent with preferential expression of the maternal Pgk-1 allele in the trophoblastic cells of the outgrowths, while both alleles are expressed in inner-cell-mass cells. The results strongly support the idea that non-random X-chromosome expression is due to preferential paternal X inactivation in trophectoderm (from which extraembryonic ectoderm is derived) and in primary endoderm, and not to cell selection.
Localization of microfilament bundles in the upper layer of the primitive-streak-stage chick blastoderm
Authors: Vakaet L. , Vanroelen CH. 
Published: April 2021

ABSTRACTTransmission electron microscopy of medium-streak-stage chick blastoderms revealed the presence of 4-6 nm microfilament bundles just under the apical surface of upper layer cells, in close association with the junctional complex. The presence of these microfilament bundles was not restricted to the centre of the primitive streak, but they were also observed in the presumptive neural plate and lateral to the anterior half of the primitive streak. The microfilament bundles are thought to be involved in every morphogenetic movement in the upper layer and not to be restricted to groove formation.
Influence of a temporary embryonic testis graft on the regression of Müllerian ducts in female chick embryo
Authors: Maraud R. , Rashedi M. , Stoll R. 
Published: April 2021

ABSTRACT
Whole testes of 13-day-old chick embryos grafted according to an original method into the extraembryonic coelom of 3-day-old recipients were next removed up to day 6.
The temporary presence of a testis allowed the Müllerian ducts to retrogress, from day 8, in a high percentage of female hosts. It can be concluded that the graft secreted into the blood of the embryo enough ‘anti Müllerian hormone’ to provoke regression of ducts at least 2 days after its removal and that the reaction of ducts depends on the appearance of their sensitivity to this hormone.
Investigation of cell lineage and differentiation in the extraembryonic endoderm of the mouse embryo
Authors: Gardner R. L. 
Published: April 2021

ABSTRACTThe technique of injecting genetically labelled cells into blastocysts was used in an attempt to determine whether the parietal and visceral endoderm originate from the same or different cell populations in the early embryo. When the developmental potential of 5th day primitive ectoderm and primitive endoderm cells was compared thus, only the latter were found to colonize the extraembryonic endoderm. Furthermore, single primitive endoderm cells yielded unequivocal colonization of both the parietal and the visceral endoderm in a proportion of chimaeras. However, in the majority of primitive endodermal chimaeras, donor cells were detected in the parietal endoderm only, cases of exclusively visceral colonization being rare. Visceral endoderm cells from 6th and 7th day post-implantation embryos also exhibited a striking tendency to contribute exclusively to the parietal endoderm following blastocyst injection.The above findings lend no support to a recent proposal that parietal and visceral endoderm are derived from different populations of inner cell mass cells. Rather, they suggest that the two extraembryonic endoderm layers originate from a common pool of primitive endoderm cells whose direction of differentiation depends on their interactions with non-endo-dermal cells.
A genetic analysis of the determination of cuticular polarity during development inDrosophila melanogaster
Authors: Gubb D. , García-Bellido A. 
Published: April 2021

AbstractThe polarity mutants pk, sple, mwh, fz and in alter the orientations of cuticular processes in several regions of the body. The mutant polarity patterns are constant and do not result from alterations in cell lineage. Polarity patterns are locus specific rather than allele specific (new alleles express the same polarity patterns as the original alleles). In the wing, polarity formation is largely cell autonomous and is independent of the anteroposterior compartment boundary. By genetic and physiological manipulation it is shown that the mutant polarity patterns are unaffected by the size of the wing blade or the number of cells that form it. Mutants which remove parts of the wing margin or alter the distribution pattern of wing veins do not alter the mutant polarity patterns. Thus, neither the wing margins nor the pattern of vein tissue act as spatial references for polarity formation. The determination of mutant polarity patterns is not dependent on the overall topology of the wing blade but is region-specific. The mutants affect several independent functions. The possible wild-type function of the loci in polarity formation is discussed.
Regulation of ciliary pattern in Dileptus (Ciliata).:I. Sensory cilia and their conversion into locomotor cilia
Authors: Golinska Krystyna 
Published: April 2021

ABSTRACT
The surface of Dileptus contains three different regions: locomotor, oral and sensbry. Each region has cilia with a specific structure and arranged in a characteristic pattern. In the morphogenetic situation when a sensory region transforms into a locomotor one, sensory cilia undergo structural changes converting them into locomotor cilia. The evidence for this is that cilia are found in the transforming region with an inner microtubular pattern intermediate between that of sensory and locomotor cilia. There are also changes in distribution of sensory units leading to a pattern characteristic of locomotor cilia. The conversion of sensory cilia into locomotor ones is also confirmed by a complete lack of evidence for resorption of sensory units within the transforming region, although the resorption is usually very easily observed with the transmission electron microscope. Transformation lasts about 5 h after the operation ; afterwards locomotor cilia of normal appearance occupy the transformed region.
This way of regulation of ciliary pattern has not been previously described. Its most surprising feature is the regulation of inner structure in an already differentiated ciliary unit. Some aspects of mechanisms which could control this kind of pattern regulation, are discussed.
Preimplantation development of gynogenetic diploid mouse embryos
Authors: Borsuk Ewa 
Published: April 2021

ABSTRACT
Diploid gynogenetic mouse embryos were produced in a three-step procedure : fertilization in vitro, suppression of the 2nd polar body formation by Cytochalasin B, and microsurgical removal of the male pronucleus. The operated eggs were transplanted to the oviduct of recipient females for 72 or 96 h. The overall recovery rate was 73%, but compacted morulae and blastocysts constituted only 28-6% of transplanted eggs. After 72 h blastocysts were rare (3·5%) but 24 h later their incidence increased to 21·2%. In eggs homozygous for T6 chromosome it was possible to prove karyologically that the male pronucleus was effectively removed and that the diploid genome was of purely maternal origin.
An autoradiographic analysis of tissue potency in different regions of the embryonic ectoderm during gastrulation in the mouse
Authors: Beddington R. S. P. 
Published: April 2021

ABSTRACTIn vitro chimaeras have been produced by injecting [3H]thymidine-labelled 8th day embryonic ectoderm, derived from the anterior, distal or posterior regions of the egg cylinder, into unlabelled synchronous embryos. Injected embryos were cultured for 36 h and the distribution of donor cells was analysed autoradiographically. One series of orthotopic injections was carried out and the results indicate that the developmental fate of embryonic ectoderm in the posterior part of the embryo is to form mesoderm, both embryonic and extraembryonic. Heterotopic injections of distal and posterior embryonic ectoderm demonstrate that these tissues readily conform to the colonisation patterns characteristic of their new location. In contrast, anterior embryonic ectoderm showed some preference for definitive ectoderm differentiation following heterotopic transplantation. However, there was no evidence that the normal fate of tissue from the three regions studied could be explained by pre-existing mosaicism in the embryonic ectoderm.
Induction of bone by epithelial cell products
Authors: Hall Brian K. , van Exan R. J. 
Published: April 2021

ABSTRACT
The bones of the head and face of vertebrate embryos only form after their progenitor cells have undergone an inductive interaction with embryonic epithelia. We have investigated whether epithelial cell products can substitute for epithelia in allowing mandibular ecto-mesenchyme to form bone. Mandibular epithelia from embryonic chicks were cultured on Millipore filters for 28 days to allow them to deposit an extracellular matrix, shown by electron microscopy to be a basal lamina-like material. Mandibular ectomesenchymal cells formed bone when placed on to these epithelial extracellular products and grafted to chorio-allantoic membranes of host embryos. Treatment of epithelial cultures with trypsin or L-azetidine-carboxylic acid removed both the extracellular products and their ability to induce bone formation. Hyaluronidase treatment did neither. We concluded that a protein-aceous component of epithelial basal lamina provides a sufficient inductive stimulus to initiate differentiation of bone within mandibular ectomesenchyme.
Regulation of the pattern of basal bodies within the oral apparatus ofTetrahymena thermophila
Authors: Bakowska Julita , Frankel Joseph , Nelsen E. Marlo 
Published: April 2021

ABSTRACTThe number and arrangement of basal bodies included in the four compound ciliary organelles making up the mature oral apparatus of Tetrahymena thermophila ordinarily vary only slightly. Severe starvation brings about formation of oral structures with a reduced number of basal bodies within these organelles, and sometimes with a complete loss of one of the component organelles. Such reductions are stringently specified in spatial terms, but they do not represent simple and proportional shrinkage of the organelle complex. Instead, certain spatial features remain essentially unaltered, while others undergo major quantitative reductions, resulting in large changes in the internal proportions of the structures. This selective regulation can be explained in terms of the different parallel and sequential processes taking place during the development of this organelle complex. There is also no strict pro-portionality between the size of the oral apparatus and that of the cell ; instead, oral apparatuses become relatively larger as cells become smaller. This is due in part to the inherent temporal discontinuity of oral development, but there is probably also a real change in the oral/body size relation at the time of oral development. The ‘French flag’ rule fails when applied to the relative sizes and internal proportions of organelle systems in this and in other ciliates.
Studies on the Mode of Outgrowth of the Amphibian Pronephric Duct
Authors: Overton Jane 
Published: April 2021

ABSTRACT
The mode of outgrowth of the pronephric duct has been investigated by examining the mitotic index and migratory propensities of duct cells. There is no indication of duct elongation through terminal proliferation or of high proliferative activity throughout the duct that does not merely reflect the generally high growth rate of the embryo as a whole. Explants of the trunk region cultured in plasma clots showed cylindrical extensions of pronephric duct cords into the clot prior to outgrowth of other cell types. It is concluded that in the species studied, duct outgrowth is an essentially migratory phenomenon, and that the nephric epithelial cells have the ability to form cords of roughly normal diameter in a non-cellular environment.
The Adhesive Properties and Expansion of the Chick Blastoderm
Authors: New D. A. T. 
Published: April 2021

ABSTRACTChick blastoderms during the first 2 days of incubation are unable to expand if the blastoderm edge is detached from the vitelline membrane. The edge can, however, reattach, and then expansion continues. The blastoderm edge is very sensitive to the nature of the substrate surface. It did not form normal adhesions with, or expand normally over, vitelline membranes that had been boiled or (with one exception) treated with formalin. Neither will it expand over the outer surface of the vitelline membrane (i.e. the surface which in ovo faces the albumen). It will, however, expand over alcohol-treated vitelline membranes. The blastoderm is sensitive to lines of tension in the vitelline membrane, extending fastest along lines of greatest tension. The marginal cells of the blastoderm adhere to the vitelline membrane as a result of their intrinsic properties, and not because of their peripheral position. Expansion of the blastoderm is dependent on a mechanical tension produced by the outward-moving margin. Expansion can occur without protein synthesis, but if yolk protein is available it will be utilized. Albumen protein is not used at this stage. Cell proliferation is particularly active in the marginal region of the blastoderm (though not at the extreme edge). The ectoderm in the marginal region becomes several cells thick if blastoderm expansion is prevented. Blastoderms inverted on the vitelline membrane develop into hollow vesicles. Blastoderms grown on inverted vitelline membranes adhere abnormally strongly to the membranes and fold the membranes at the region of attachment.
Differentiation of Cells of the Rana pipiens Gastrula in Unconditioned Medium1
Authors: Barth Lester G. , Barth Lucena Jaeger 
Published: April 2021

ABSTRACT
A method has been devised for the culture of gastrular cells of R. pipiens. Histological and functional differentiation of nerve, muscle, and pigment cells is described as well as the differentiation of ciliated, mucus-secreting, and notochord cells. The inner layer of the presumptive epidermis differentiates into nerve-cells, ciliated cells, and ‘giant’ cells, in addition to an unidentified cell type X. Brief lithium treatment of presumptive epidermis results in a permanent transformation into pigment cells and mesenchyme.
The developmental potential of a euploid male teratocarcinoma cell line after blastocyst injection
Authors: Rossant J. , McBurney M. W. 
Published: April 2021

ABSTRACTA karyotypically normal male embryonal carcinoma (EC) cell line, P19, produced large numbers of chimaeras in midgestation after groups of cells were injected into mouse blastocysts. A wide variety of apparently normal tissues were colonized by the EC cells but most chimaeras were also morphologically abnormal. Few live chimaeras were produced and all contained tumours of EC cell origin as well as EC contributions to normal tissues. This apparently incomplete regulation of the EC cells by the embryonic environment was not due to EC cell variation, since a clonal subline, P19S18, produced similar patterns of colonization. It was also not caused by the inability of the blastocyst to regulate large numbers of injected EC cells, since a single P19S18 cell could contribute to both normal and tumour tissue in the same mouse. Neither a high rate of colonization of the embryo nor a normal karyotype is, therefore, sufficient to ensure reversion of EC cells to normal embryonic behaviour.
The effect of teratogenic antiserum on yolk-sac function in rat embryos cultured in vitro
Authors: Freeman Stuart J. , Brent Robert L. , Lloyd John B. 
Published: April 2021

ABSTRACT
The teratogenicity of rabbit anti-rat visceral yolk-sac antiserum, injected into pregnant rats at either 8 ·5 or 9 ·5 days of gestation, has been confirmed. Normal rabbit serum was found not to be teratogenic.
When conceptuses from 9 ·5-day pregnant rats were cultured for 48 h in heat-denatured homologous serum, to which antiserum was added for the final (or the penultimate) 6 h of culture, embryonic development was normal. The protein contents of embryos and yolk sacs (at harvesting) were however decreased.
When antiserum was present in cultures for the final 6 h, pinocytosis by the yolk sac, as measured by the uptake of 125l-labelled polyvinylpyrrolidone (PVP), was decreased to an extent related to the concentration of antiserum in the culture medium and to a minimum level of about 40%. The presence of antiserum in cultures for the penultimate 6 h only, with 125I-labelled PVP present for the final 6 h only, produced an identical result. No uptake of radioactivity into the embryo was observed, in either the absence or presence of antiserum.
When conceptuses were cultured for the final 6 h in vitamin- and glucose-supplemented dialysed homologous serum whose proteins were [3H]leucine-labelled, the presence of antiserum for either the final or penultimate 6 h again resulted in a decrease in the uptake of radioactivity by conceptuses. Uptake of radioactivity into yolk sac and embryo was decreased by the same amount, indicating that proteolysis in yolk-sac lysosomes was not inhibited.
In parallel control experiments in which normal rabbit serum replaced rabbit anti-rat visceral yolk-sac antiserum, no effects on embryonic development, on protein contents of yolk sacs and embryos at harvesting, or on the uptake of radioactivity by conceptuses were observed.
These results are interpreted as providing evidence that teratogenic antibodies decrease pinocytosis of protein by visceral yolk sac at the early organogenesis stage and consequentially decrease the availability of amino acids and thus protein synthesis in both yolk sac and embryo. It is proposed that this effect constitutes the mechanism of action of teratogenic antisera.
Neuronotrophic effects of skeletal muscle fractions on spinal cord differentiation
Authors: Hsu L. , Natyzak D. , Trupin G. L. 
Published: April 2021

ABSTRACT
Soluble fractions of homogenized skeletal muscle were found to promote neuronal migration and neuritic and glial outgrowth from embryonic chick spinal cord explants. Fractions obtained from skeletal muscle immobilized by prolonged treatment with curare were significantly more effective than normal muscle in accelerating neuronal and glial development. Fractions from other tissues such as brain and lung did not enhance neuronal differentiation, but were effective in stimulating outgrowth of glial cells. Separate measurements of glial and neuronal responses indicate that tissue fractions produce independent effects on the glial and neuronal components.
Incorporation of 5-bromo-2’-deoxyuridine into mesenchymal limb-bud cells destined to die: relationship to polydactyly induction in rats
Authors: Wise L. David , Scott William J. 
Published: April 2021

ABSTRACT
The thymidine analogue, 5-bromo-2’-deoxyuridine (BUdR), given at the proper dose and time to pregnant rats produces preaxial hindlimb polydactyly in a high proportion of near term foetuses. The lack of physiological cell death in an area of preaxial mesenchyme known as the foyer primaire preaxial (fpp) is thought to be important in the pathogenesis of this defect. This study addresses the question of whether BUdR’s well-known antidifferentiative effects, which are due in some way to drug incorporation into DNA, are operative in this in vivo system. The dose and temporal response of BUdR for the induction of preaxial polydactyly inversely parallels the frequency of embryonic hindlimbs with an fpp. Incorporation of BUdR into degenerative fragments within the fpp of these treated limbs is demonstrated with indirect immunofluorescence using an antibody to bromouridine. Hindlimbs exposed to a threshold dose of BUdR at the optimal time for producing polydactyly have incorporated the drug into degenerative fragments within the fpp. This suggests that a higher, teratogenic dose of BUdR might likewise be incorporated. The resulting higher level of incorporation presumably alters the normal course of terminal differentiation for these cells originally destined to die.
Teratogenic doses of BUdR injected at later than the optimal time are also incorporated into dead cell fragments within the fpp, suggesting that presumptive dead cells have additional rounds of DNA synthesis which are BUdR-insensitive. Approximately 12 h prior to overt death presumptive fpp cells no longer incorporate the drug.
Results reported support the hypothesis that incorporation of teratogenic levels of BUdR prevent cell death in the fpp. The extra cells are thought to contribute directly or indirectly to the added digit. Contrary to other views, it is suggested that BUdR-induced teratogenesis can be a result of the drug’s antidifferentiative effects on specific, ‘sensitive’, populations of cells.