bluuebunny/crossref_metadata_2025_split huggingface dataset:
La Régénération caudale des Urodèles (Induction et réactivité du territoire)
Authors: Kiortsis par V. , Droin A. 
Published: April 2021

ABSTRACT
The role played by the spinal cord and other tissues in the regeneration of the tail was studied in larval salamanders.
Transverse tail-slices, with or without spinal cord, grafted to the back may undergo a reduction in size, or remain stationary, or even regenerate new structures. A more marked reduction was observed in the despinalized grafts. After partial amputation of the tail, a despinalization of the stump was performed without injuring the other tissues. In all cases where the absence of the spinal cord was proved histologically, no regeneration of the mesodermal axis occurred. Only a fin-like regenerate without muscles or skeleton appeared at the amputation surface. Spinal ganglia or brain (telencephalon), substituted for the spinal cord of the tail, were unable to replace it in its inductive action. An increase of the nerve supply, by introducing the two sciatic nerves into the despinalized tail-stump, also had no effect. It seems that the inductive action exerted by the spinal cord on tail regeneration is specific. The lateral deflexion of the spinal cord was enough to induce a supernumerary tail. If the deflexion was done dorsolaterally, instead of laterally, the induced supernumerary tail formed a half-fin too. Segments of the spinal cord, grafted dorsally or ventrally into the tail-fin, at some distance from the main axis, did not induce any muscular or skeletal structures. It is believed that the organ district of the tail contains at least two zones of different morphogenetic potencies : one mesodermal, which regenerates the main axis of the organ, under the inductive influence of the spinal cord, and one, derived from the neural crest, which produces, even in the absence of the spinal cord, a fin-like structure.
The Effect of Delayed Brain Extirpation and Replacement on Caudal Regeneration in Nereis diversicolor
Authors: Clark R. B. , Evans S. M. 
Published: April 2021

ABSTRACT
Extirpation of the supra-oesophageal ganglion of Nereis diversicolor before or up to 48 hours after amputation of a number of posterior segments inhibits caudal regeneration. Extirpation of the ganglion 3 or more days after amputation of segments retards but does not inhibit regeneration. Injection or implantation of supra-oesophageal ganglia of regenerating worms into decerebrate hosts 48 hours or more after amputating the posterior segments results in segment proliferation in some of the recipients. Replacement of ganglionic material before 48 hours has no effect. The types of regeneration observed following replacement therapy on the 3rd or 4th days is characteristic of that when there has been a limited migration of coelomic cells to the wound. ‘Regeneration’ hormones appear to be present in the ganglion 48 hours after the loss of posterior segments, but they do not circulate in the body in effective quantity until 24 hours later.
Réaction de l’embryon de Poulet au bleu trypan
Authors: Stéphan par F. , Sutter B. 
Published: April 2021

ABSTRACT
En 1941, Ancel & Lallemand signalaient que le bleu trypan était tératogène pour l’embryon de Poulet. Depuis lors de nombreux chercheurs ont utilisé le même produit avec des résultats quelque peu différents suivant les groupes de vertébrés testés : Oiseaux, Mammifères et Batraciens.
Perturbations indirectes de l’organogénèse cardio-vasculaire obtenues par la destruction aux rayons X de territoires situés en arrière de l’ébauche du cœur
Authors: Douarin par Nicole Le 
Published: April 2021

ABSTRACT
De nombreuses techniques permettent de perturber l’organogénèse du cœur et des arcs aortiques chez les embryons de Vertébrés. Les unes agissent sur l’ensemble de l’organisme embryonnaire: action de la thyroxine (Bauman & Pfister, 1936), carence vitaminique de la femelle gestante (Wilson & Warkany, 1949) ou hypoxie temporaire de l’œuf en incubation (Rubsaamen & Schellong, 1953). D’autres techniques, au contraire, ont été appliquées directement sur le système artériel. Elles ont consisté en des destructions par l’électrocautère (Bremer, 1928) ou en des ligatures (Stéphan, 1952). Elles ont eu pour conséquence non seulement des perturbations du système artériel, mais également des malformations cardiaques. Enfin, l’irradiation aux rayons X du cœur de l’embryon de Poulet, réalisée suivant la technique mise au point par Ancel & Ét. Wolff (1934), a permis d’obtenir des embryons présentant d’importantes anomalies du cœur et des vaisseaux (G. Le Douarin & N. Le Douarin, 1959; G. Le Douarin, 1960).
Malformations résultant d’irradiations localisées de différentes parties de l’ébauche cardiaque chez l’embryon de Poulet
Authors: Douarin par Georges Le 
Published: April 2021

ABSTRACT
L’irradiation aux rayons X de la totalité de l’ébauche cardiaque, pratiquée sur l’embryon de Poulet au 3ème jour de l’incubation, provoque des malformations cardiovasculaires qui, en ce qui concerne le cœur, intéressent la morphologie externe de l’organe ainsi que sa constitution interne. Ces résultats ont été décrits dans un travail antérieur (G. Le Douarin, 1960).
A quantitative analysis of regeneration from chimaeric limb stumps in the axolotl
Authors: Muneoka Ken , Holler-Dinsmore Gregory V. , Bryant Susan V. 
Published: April 2021

ABSTRACT
We have analysed the cellular contribution and cellular displacement which occur during regeneration from chimaeric (half triploid, half diploid) lower arms in the axolotl. In general both anterior and posterior halves contribute approximately 50 % of the regenerated limb cells. Deviations from equal contribution were observed only when anterior tissue was grafted, suggesting that anterior tissue is more sensitive to grafting operations. Approximately 25 % of all cells in the regenerated limb were found to be displaced to the opposite side of the limb. Cellular displacement was not random; 63 % of all displaced cells were found in regions adjacent to the tissue of origin.
The differentiation of germ cells and gonads during development of carp (Cyprinus carpio L.). A study with anti-carp sperm monoclonal antibodies
Authors: Parmentier H. K. , Timmermans L. P. M. 
Published: April 2021

ABSTRACT
Gonadal development, germ cell differentiation and the appearance of membrane antigenic determinants, specific for male and female germ cells during gonadogenesis, was studied in larval and juvenile carp (Cyprinus carpio L.) until 25 weeks after fertilization.
Indirect immunofluorescence studies with four monoclonal antibodies raised against carp spermatozoa revealed that monoclonal antibody WCS 29 stained the outer membranes of primordial germ cells in larvae from 3 days after fertilization. The monoclonal antibodies WCS 3 and 17 reacted with the outer membranes of germ cells from 7 weeks after fertilization onwards, simultaneously with the onset of germ cell proliferation. With monoclonal antibody WCS 28 germ cell membranes were clearly stained from 18 weeks after fertilization. Similar reactions were observed in both sexes, however, female germ cells reacted at an earlier developmental stage with the monoclonal antibody WCS 28 than male germ cells.
In the developing testis the monoclonal antibodies stained all types of spermatogenic cells. In the ovary, however, only oogonia and early prophase oocytes showed a positive reaction with the four monoclonal antibodies.
The results indicate that germline-specific antigens are present on the outer membranes of primordial germ cells and their male and female descendants, with the exception of elderly oogenic stages. It is assumed that the appearance and disappearance of these membrane antigens reflect differentiation steps of germ cells during gonadogenesis.
Action of phorbol myristate acetate (PMA) at fertilization of mouse oocytes in vitro
Authors: Niemierko Anna , Komar Aldona 
Published: April 2021

ABSTRACT
Phorbol ester (PMA) in concentration 5 and 10 ng ml-1 blocks cytokinesis of the second maturation division in mouse oocytes. Karyokinesis is not impaired and digynic triploid oocytes are obtained which undergo first cleavage division.
Effectiveness of blocking cytokinesis is dependent on the timing of exposure of oocytes to PMA action. When oocytes are subjected to PMA at the onset of the second maturation division only 14·5 % of eggs are triploid. PMA present during fertilization in vitro (about 1 h exposure to PMA) induces triploidy in 40 % eggs. Extending the time of exposure of oocytes to 2 h produces 76 % tripronucleate eggs.
Applicability of PMA is compared with the use of cytochalasin B to induce triploidy in the mouse.
Contrabithorax and the control of spatial expression of the bithorax complex genes of Drosophila
Authors: Casanova Jordi , Sánchez-Herrero Ernesto , Ginés Morata Ginés 
Published: April 2021

ABSTRACT
Cbx 1 is a dominant mutation of the bithorax complex (BX-C) of Drosophila partially transforming the second thoracic (T2) segment towards the third one (T3). Molecular analysis has shown that Cbx1 arose from a transposition within the BX-C of a DNA fragment of 17 kb containing pbx+ inserted into the Ubx area. In addition to the dominant phenotype, the Cbx1 mutation produces a set of recessive homeotic transformations that we show are characteristic of the Ubx mutations. We present evidence that the dominant and the recessive transformations arise from different mechanisms and suggest the dominant transformation is caused by an alteration of the normal regulatory role of pbx+ resulting in an adventitious expression of some Ubx+ products in T2, while the Ubx phenotype is caused by the breakpoint of the insertion.
A Monoclonal antibody against mouse oocyte cytoskeleton recognizing cytokeratin-type filaments
Authors: Lehtonen E. 
Published: April 2021

ABSTRACT
Monoclonal antibodies were raised to detergent-extracted cytoskeleton preparations of mouse oocytes. In immunofluorescence microscopy, one of the antibodies, OCS-1, localizes exclusively to epithelial cells in frozen tissue sections, including various simple and stratified epithelia. The antibody decorates a keratin-type of fibrillar, vinblastine-resistant network in various cultured, epithelial-type cells, but not in myoid or fibroblastoid cells.
In mouse oocytes and cleavage-stage embryos, the OCS1 antibody gives a diffuse, spotty staining pattern. In blastocyst-stage embryos, the antibody reveals a keratin-type filamentous organization in the trophectoderm cells. In immunoelectron microscopy, the OCS-1 antibody decorates 10 nm-thick filaments, often identifiable as desmosome-attached tonofilaments, in detergent-treated trophectoderm cells.
The antigen(s) recognized by the OCS-1 antibody is apparently present in, or closely associated with, cytokeratin filaments. In addition to mouse oocytes and early embryos, a wide variety of epithelial cells in various species seem to share this antigen(s). The present results suggest that at the early stages, the cytokeratin-related antigen(s) defined by the OCS-1 antibody are stored in a non-fibrillar form which is then converted into a fibrillar network at the blastocyst stage. A pre-existing supply of cytokeratin-related protein may be essential for the development of the blastocyst.
Induction of cell–cell adhesion by monovalent antibodies in a germ cell culture
Authors: Ho Wai Chang , Bechtol Kathleen B. 
Published: April 2021

ABSTRACT
Four monoclonal antibodies, XT-I, MT-23, MT-24 and MT-29, that bind the XT-1-differentiation-antigen of male germ cells have been used to investigate the biological role of the XT-1-molecule of germ cells in short-term primary culture. Cultures from 10 days postpartum mice demonstrate increasing numbers of antigen-positive germ cells and increased antigen expression per cell with succeeding days of culture. Treatment of the antigen-positive cultures with three of the monoclonal antibodies, XT-I, MT-23 and MT-24, increases germ cell-germ cell adhesion in a dose-dependent fashion. Treatment with the fourth monoclonal antibody, MT-29, does not induce cell adhesion. The monovalent, Fab fragment of XT-I-antibody also elicits tight cell adhesion, thus ruling out antibody cross linking of molecules or cells. Saturating or near saturating amounts of the positive antibodies are required to produce adhesion, a result consistent with perturbation of a function that is performed by the sum of action of many of the XT-1-molecules on the cell. The ability of germ cells to undergo antibody-elicited tight adhesion is dependent on germ cell age and/or XT-1-antigen concentration. We hypothesize that the XT-1-molecule is involved in regulation of cell adhesion, an event which must occur in normal development.
Factors guiding regenerating retinotectal fibres in the frog Xenopus laevis
Authors: Fawcett J. W. 
Published: April 2021

ABSTRACT
I have examined the pathways of retinotectal fibres regenerating back to the contralateral tectum, and also to innervated and ‘virgin’ ipsilateral tecta in postmetamorphic Xenopus. The fibres were visualized by HRP labelling of either the whole optic nerve, or a selected quadrant of the retina.
Most fibres grow into either the ipsilateral or contralateral optic tract, although a small proportion go down the outside of the contralateral optic nerve. In the tracts, many fibres grow superficially, close beneath the pia, but a variable proportion runs more deeply. Axonal growth is not, therefore, restricted absolutely to the subpial region in the postmetamorphic Xenopus brain.
Fibres growing onto the contralateral, or a ‘virgin’ tectum mostly grow straight onto the rostral margin of the tectal lobe, without growing around its margin in the form of a medial or lateral brachium. Most of these fibres grow through the deeper part of the tectal layer which normally contains optic neuropil, but a proportion of them grow immediately deep to the pia. Fibres regenerating to an innervated ipsilateral tectum mostly enter either the medial or lateral brachium of the optic tract, and only leave this close to their site of termination. In the brachia the fibres run superficially under the pia, but when they leave the brachia they mostly run through the deeper retinorecipient layers. These observations provide further evidence that ingrowing optic fibres have their pathways influenced by the axons which have preceded them.
Cytological analyses of factors which determine the number of primordial germ cells (PGCs) in Xenopus laevis
Authors: Akita Yasuko , Wakahara Masami 
Published: April 2021

ABSTRACT
Correlation of the number of primordial germ cells (PGCs) at stage 47 with the amount of germ plasm at the 8-cell stage and with the number of the germ-plasm-containing cells (GPCCs) was analysed using two different laboratory-raised colonies of Xenopus laevis, HD and J groups. The average number of PGCs in J group tadpoles was significantly larger than that in HD group tadpoles. The amount of germ plasm in J group embryos was also demonstrated to be larger than in HD group embryos. The amount of germ plasm was related positively to the number of GPCCs at the 8-cell stage and to the resulting number of PGCs; embryos which contained larger amounts of germ plasm developed larger numbers of PGCs at stage 47.
The average number of PGCs in experimentally induced triploid tadpoles was exactly two-thirds of that in normal diploid tadpoles. Furthermore, in somatic cells (e.g. epidermis, muscle, pancreas), the number of cells in the triploid was also two-thirds of that in diploid tadpoles.
These findings suggest that the number of PGCs is regulated by at least two different mechanisms: first, the number of PGCs is primarily specified by the intrinsic amount of germ plasm in the fertilized egg. Second, it is regulated by an unknown mechanism which controls the total number of cells of whole embryos, such as the nucleocytoplasmic ratio.
Changes in the distribution of membranous organelles during mouse early development
Authors: Maro Bernard , Johnson Martin H. , Pickering Susan J. , Louvard Daniel 
Published: April 2021

ABSTRACT
The unfertilized oocyte, fertilized egg and early embryo (2-cell to 16-cell) of the mouse have been examined immunocytochemically for the distribution of antigens associated with the endoplasmic reticulum, the lysosomal and acidic vesicle fraction (100kD antigen), Golgi apparatus (135kD antigen) and coated vesicles (clathrin). The distribution of these antigens has also been examined in isolated 8-cell and 16-cell-stage blastomeres of various ages and phenotypes. Endoplasmic reticulum is detected only weakly in the oocyte and egg, but is seen abundantly at later stages both in association with the nuclear membrane and evenly distributed throughout the cytoplasm, except in regions of cell: cell apposition from which it is excluded. Intracellular clathrin is associated with the spindle in mitotic and meiotic cells. During interphase, clathrin is distributed throughout the cell until the mid-8-cell stage when it is concentrated into the apical region of the cell under the region of membrane at which a surface pole of microvilli will form subsequently. Thus, the cytoplasmic polarization of clathrin precedes overt polarization at the surface. At mitosis, the clathrin relocates to the spindle and is distributed to both daughter cells. It resumes an apical location beneath the surface pole of microvilli in polar daughter 1/16 cells, but remains dispersed in apolar daughter 1/16 cells. Both the lysosomal and Golgi antigens are distributed throughout the cytoplasm until the early 16-cell stage. In pairs of 16-cell blastomeres both antigens aggregate in a single cluster and do so whether the surface phenotype of the blastomeres is polar or apolar. The position of this cluster is not consistently related to the point of contact with the other cell in the pair but there is a suggestion that in cells with a polar surface phenotype the polar foci of Golgi/lysosomal antigens are located between the nucleus and the surface pole at earlier time points, but shift to a position between the basolateral membrane and the nucleus at the later time point. In intact 16-cell embryos also, the aggregated Golgi/lysosomal antigens of polar cells appear to localize to the basal region. The distributions of these various organelles in embryonic cells reported here show a number of differences from those reported previously for mature, differentiated cells.
Saccharide structures of the mouse embryo during the first eight days of development: Inferences from immunocytochemical studies using monoclonal antibodies in conjunction with glycosidases
Authors: Pennington J. E. , Rastan S. , Roelcke D. , Feizi T. 
Published: April 2021

ABSTRACT
Monoclonal anti-carbohydrate antibodies have been used in conjunction with glycosidases in immunofluorescence studies to derive information about the structures and in situ distribution of saccharides of the mouse embryo during the first 8 days of development. The salient findings are as follows: Branched poly-N-acetyllactosamine sequences of I-antigen type are detectable from the first day onwards and are widely distributed in cells of the endoderm, ectoderm and mesoderm.Linear poly-N-acetyllactosamine sequences of i-antigen type are detectable from the fifth day onwards in cells of all three lineages, but have a more restricted distribution than the sequences of I-type.Poly-N-acetyllactosamine sequences that are susceptible to digestion with endoβ-galactosidase are the main carriers of the SSEA-1, C14 and the blood group B-like antigens, which have the following structures and are found in endoderm and ectoderm but not in mesoderm cells. In the trophoblast however, these antigens are borne on saccharides that are resistant to endo-β-galactosidase.A proportion of the poly-N-acetyllactosamine structures in the endoderm and the ectoderm of the 5- and 6-day embryos may contain the following novel structures: in which antigenicities of SSEA-1 and C14 determinants are masked.There are several types of sialyl-oligosaccharides: (1) those reactive with anti-Gd, which has a specificity for NeuAc α2 –3Gal β1 –4GlcNAc sequence in the extraembryonic mesoderm and the heart; (2) those reactive with anti-Pr2 but not with anti-Gd, which may correspond to other N-acetylneuraminic acid containing sequences such as NeuAc α2 –3Gal β1 –3GalNAc or NeuAc α2 –6Gal in preimplantation embryos and in the yolk sac, neural ectoderm and mesenchyme of the 8-day embryo; (3) those with other sialic acid forms or linkages that do not react with anti-Gd and Pr2; among these are sialosyl-i sequences in the extraembryonic ectoderm, and sialosyl-I sequences in most cell types during the first 8 days. The latter are the main poly-N-acetyllactosamine structures in the neural ectoderm of the 8-day embryo.The sequence Gal β1 –3GlcNAc β1 –3Gal βl –4Glc/GlcNAc, or cross-reactive structures, which bind FC10.2 antibody occur in the extraembryonic endoderm and yolk sac.
The roles of specific carbohydrate structures as receptors during embryonic development and cell growth are important topics of current research. The cytochemical approach with monoclonal antibodies in conjunction with glycosidases, as in the present study, provides a unique opportunity to visualize the in situ disposition of specific carbohydrate sequences in individual cells of the whole organism, and should facilitate systematic investigations of their functions.
Measurement of biological shape: a general method applied to mouse vertebrae
Authors: Johnson D. R. , O’Higgins P. , Mcandrew T. J. , Adams L. M. , Flinn R. M. 
Published: April 2021

ABSTRACT
A method is described for recording and analysing the projected shape of mouse vertebrae. The image of the shape is captured by a television camera, cleaned, digitized and subjected to mathematical analysis. A visual representation is obtained by reconstructing the shape in polar coordinates about its centre of area. Further statistical analysis of the whole shape is performed after a Fourier transform. This allows the shape to be represented by and reconstructed from 15 numbers. The method does not rely on homologous points or expert opinion and allows mean shapes to be constructed. It successfully distinguished between 92 % of the test data, T1 and T2 vertebrae from two strains of mice.