bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sur l’origine du sang et des vaisseaux chez Lebistes reticulatus (Téléostéen)
Authors: Colle-Vandevelde par A. 
Published: April 2021

ABSTRACT
The erythroblasts of the Teleost Lebistes reticulatus, when visualized with the Unna-Brachet technique, appear at the 2-somite stage of development. The earliest visible erythropoiesis is then located in the ventral part of the border of the blastodisc. Along this border it rapidly extends towards the posterior extremity of the embryo, where it appears continuous with the elements of the ‘Intermediare Zellenmasse’ of Oellacher.
The blood-forming rudiment in the embryo itself becomes visible only at the stage of 5 somites, and takes the shape of an inverted Y whose long limb is localized in the midline of the posterior somitic region of the embryo; the two branches of the Y taking their origin in the posterior part of the extra-embryonic tissue on both sides of the terminal node.
Blood-circulation becomes apparent at the 15–17-somite stage, and at the surface of the yolk the blood-cells then move towards the venous side of the heart. The closure of the blastopore occurs around the stage of 18 somites, when the blood-circulation is already established.
These observations do not correspond with what is found in other Teleosts where the blood-forming rudiment appears to be situated only in the dorsal part of the body. It would now seem possible to relate this extraordinary origin to the situation which prevails in other Vertebrates.
Transplantation et Régénération chez la Planaire Dendrocoelum lacteum
Authors: Stéphan-Dubois par Françoise , Gilgenkrantz Fernand 
Published: April 2021

ABSTRACT
A graft of prepharyngeal origin, implanted behind the mouth, tends to dominate the posterior fragment obtained by postbuccal section. If this section runs through the graft, the latter regenerates a head at its free anterior border while the host edges undergo a regulation of form. After a similar section, the graft having previously been irradiated with X rays, the postpharyngeal host region provides the graft with the necessary material for regeneration and the final result is identical with the preceding one, except that regeneration is delayed for about twelve days during which the healthy neoblasts are migrating across the irradiated graft. If the section goes between mouth and graft, no regeneration is possible at the level of section. The graft bulges dorsally, develops eyes, and its movements draw the posterior part along. A graft of postpharyngeal origin, implanted at the anterior level of a decapitated and X-irradiated worm, supplies the host with its own healthy cells, but it remains unable to perform any head regeneration from a free border running through itself.
Comparison of the Different Teratogenic Effects of Three Commercial Samples of Trypan Blue
Authors: Beck F. 
Published: April 2021

ABSTRACT
Three commercial preparations of trypan blue were injected into Wistar rats at days of pregnancy. The amount of azo dye (in terms of titratable azo linkage) administered was the same in each series. Two of the dye preparations were found to have well-marked teratogenic properties while the third was almost totally inactive. Control rats were injected with normal saline. One of the teratogenic dyes had a lower Ld50 (Kärber) than the non-teratogenic dye.
Le rôle du mesonephros de l’embryon de Poulet dans la nutrition de cellules cancéreuses
Authors: Wolff par Etienne , Wolff Emilienne 
Published: April 2021

ABSTRACTNous avons montré que plusieurs souches cancéreuses humaines, HeLa, KB, Osgood, Fogh, peuvent être cultivées sur des organes embryonnaires de poulet explantés in vitro. Le mesonephros de 8 à 9 jours est un des plus favorables à la prolifération des cellules cancéreuses (Et. Wolff & Em. Wolff, 1958, 1959). Rappelons que celles-ci ne se multiplient pas et ne survivent pas, si elles sont placées directement sur les milieux nutritifs propres aux cultures organotypiques. Par contre, elles se nourrissent des tissus du mesonephros cultivés sur ces milieux. C’est donc l’organe embryonnaire, non le milieu de culture, qui est responsable du succès de la culture. Les cellules cancéreuses se comportent comme des parasites vis-à-vis des cellules de l’organe embryonnaire. Elles se substituent à elles, par un processus encore mal élucidé, car les cellules normales au milieu desquelles pénètrent les cellules cancéreuses ne montrent pas de phénomènes de dégénérescence. Pourtant elles disparaissent en grand nombre, car des territoires considérables du mesonephros sont envahis par les cellules tumorales, qui se substituent à elles et n’en laissent subsister aucune.
Membrane organization in the preimplantation mouse embryo
Authors: Pratt Hester P. M. 
Published: April 2021

ABSTRACT
The preimplantation mouse blastocyst consists of two differentiated tissues, the troph-ectoderm (a structurally and functionally polarized epithelium) and the inner cell mass. The divergence of these two cell types can be traced back to a contact dependent polarization of the surface and cytoplasm at the 8-cell stage. Membrane/cytocortical organization during this preimplantation period has been studied using freeze fracture in conjunction with the sterol-binding antibiotic filipin in an attempt to discern the molecular basis and origin of these surface asymmetries.
The distribution of filipin reactivity within the different membrane domains showed that the surface polarity exhibited by trophectoderm and by blastomeres of the 8-cell stage is underlain by a heterogeneity in molecular organization of the membrane/cytocortex which may originate prior to the appearance of any overt surface polarity.
The results are discussed in terms of the likely basis of this membrane/cytocortical asymmetry, its probable origins and the use of the preimplantation mouse embryo as a model system for studying the assembly of a polarized epithelium.
Genetic analysis of developmental mechanisms in hydra : XVI. Effect of food on budding and developmental gradients in a mutant strain L4
Authors: Takano Jun , Sugiyama Tsutomu 
Published: April 2021

ABSTRACT
Effect of food was examined on the budding rate and the developmental gradients of a mutant hydra strain L4.
This mutant strain has very high levels of head-inhibition potential gradient along its body axis (Takano & Sugiyama, 1983). It also has a reduced budding capacity when it is cultured using brine shrimp nauplii as food, but its budding capacity is significantly improved when a small amount of tubifex worm tissue is added to its diet of brine shrimp (Takano, 1984).
To test whether or not this change of budding rate is correlated with the change in the levels of the head-activation or head-inhibition potential gradients, L4 animals were cultured on the diet of brine shrimp with or without addition of tubifex worm tissue and the budding rates and the gradient levels were examined in these animals.
The results showed that food affected the budding rate in L4 without affecting its gradient levels. This suggests that the gradient levels and the budding rate in L4 are uncorrelated to each other, and that therefore the high levels of head-inhibition potential are not the cause for the low budding rate in this strain (cf., Takano & Sugiyama, 1983).
Isolation, characterization and localization of a lectin within the vitelline membrane of the hen’s egg
Authors: Cook Geoffrey M. W. , Bellairs Ruth , Rutherford Nicholas G. , Stafford Caroline A. , Alderson Thomas 
Published: April 2021

ABSTRACT
A lectin with an affinity for certain sulphated polysaccharides, such as fucoidin and dextran sulphate, has been isolated from the vitelline membrane of hens’ eggs and purified to hom­ogeneity as assessed by two-dimensional gel electrophoresis. Polyclonal and monoclonal anti­bodies have been raised to the lectin and used in indirect immunofluorescence microscopy to localize the agglutinin in the outer layer of the vitelline membrane, where the lectin persists prior to the breakdown of the vitelline membrane. The qu antity of lectin extracted from the two layers of the membrane, which have been separated by the method of Bellairs, Harkness & Harkness (1963), correlated well with the results of immunofluorescence microscopy. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis of the two layers of the membrane indicates that each layer has a distinctive polypeptide composition, the outer layer containing in particular lysozyme and avidin.
The evidence obtained in this study indicates that the lectin is not involved in adhesion of the blastoderm to the vitelline membrane; neither is it involved in the expansion of the blastoderm nor in maintaining the strength of the membrane. The possible roles in promoting transport of solutes across the membrane as well as providing bactericidal properties to the egg are discussed.
Cell division during intercalary regeneration in the cockroach leg
Authors: Anderson Hilary , French Vernon 
Published: April 2021

ABSTRACT
In a series of grafting operations on cockroach legs, epidermal cells from different positions or from the same position on the circumference of the femur were placed together. Where cells from different positions were confronted, new cuticular structures corresponding to the positions which would normally have lain between them were formed during the following moults. At the control junctions, where cells from the same positions were placed together, no new structures were formed.
Grafted legs were examined histologically at various times after the operation. The events following grafting fell into four phases: wound healing - when epidermal cells migrated over the wound to re-establish epidermal continuity and cells adjacent to the wound divided to compensate for cell emigration; intercalation - when cell divisions took place at the host-graft borders where there was a positional discrepancy; proliferation - when the general growth of the epidermis occurred by widespread cell division; cuticle secretion - when apolysis occurred, cell division ceased, and cuticle secretion began.
The results show that intercalary regeneration is associated with local cell division at the graft-host borders, and that these divisions are not confined to the normal proliferative phase of the moult cycle, but begin much earlier in the cycle, as soon as wound healing is complete.
These results support epimorphic models (such as the Polar Coordinate Model) of pattern regulation, where change of positional value is tied to cell division, but they do not discount the possibility of a limited initial morphallactic phase.
Eyelid development and fusion induced by cortisone treatment in mutant, lidgap-Miller, foetal mice. A scanning electron microscope study
Authors: Harris M. J. , Juriloff D. M. 
Published: April 2021

ABSTRACT
In normal mice the eyelids grow across the eye and fuse together during days 15 and 16 of gestation, and the mice are born with their eyes closed. In mutant lgM1/lgM1 (lidgap-Miller) foetuses this growth and fusion does not occur and the mice are born with their eyes open. A single prenatal treatment with cortisone on day 14 of gestation masks the genetic defect, and the mice are born with their eyes closed. In the present study, a scanning electron microscope was used to investigate: (1) whether eyelid closure in cortisone-treated lgM1/lgM1 foetuses differs from that in normal foetuses of the CBA/J and ICR/M1 strains and, if so, how; and (2) how developing eyelids of untreated lgM1/lgM1 foetuses differ from normal.
The induced closure differs from normal. During their growth, eyelids of treated mutant foetuses have a deficiency of rounded periderm cells at their margins; the margin cells agglomerate and flatten prematurely. In closed eyes of treated mutants there is a gap between periderm cells of the upper and lower eyelids along part of the fusion line. Fusion is completed late, during day 17. Maturation of the head periderm is advanced in treated lgM1/lgM1foetuses on day 16, relative to normal CBA/J and untreated lgM1/lgM1 foetuses.
Untreated lgM1/lgM1 foetuses differ from normal in that the eyelids never cover the eye and lack rounded periderm cells at their perimeter. The periderm cells present form a flattened band along the eyelid margin rather than, as in normal eyelids, along the fusion line.
The results of the cortisone study suggest that the route to eyelid closure in mice may not be narrowly canalized either in cell morphology or number, or in timing, and that closed eyes may be achieved after cortisone treatment in lgM1/lgM1 foetuses as part of an induced maturation of the periderm.
The precision of pathway selection by developing peripheral axons in the axolotl
Authors: Freeman J. M. , Davey D. F. 
Published: April 2021

ABSTRACT
At the time of hindlimb development in the axolotl there is a well-established but still developing trunk innervation. The trunk innervation is primarily composed of the segmental nerves, each of which consists of a dorsal and a ventral ramus and its branches. At a few segmental levels in the region of the hindlimb a large number of additional axons arise to innervate the limb. To reach the limb, they must grow via the ventral rather than the dorsal rami.
The precision with which this pathway is selected was determined by counting axons in the dorsal and ventral rami at limb segmental levels, prior to and during the period of maximum axon proliferation. If outgrowth is highly directed rather than random, then the ratio of ventral/ dorsal ramus axons should increase significantly during the period when large numbers of additional axons are produced. In addition, since the dorsal trunk varies little in size between limb segments and immediately caudal ‘non-limb’ segments, the number of axons in the dorsal rami can be compared at the two levels. Mistaken projections should result in inordinately large axon numbers in dorsal rami at limb compared to non-limb levels.
The results show that there is approximately a tenfold increase in the ratio of ventral/dorsal ramus axons at the time of maximum outgrowth to the limb, thus the mode of distribution at the ventral-dorsal branch point is significantly altered in favour of growth toward the limb, and outgrowth appears to be highly directed rather than random. Moreover at this time there is no discernible increase in the number of dorsal ramus axons at limb levels while those at non-limb levels increase fourfold. The apparent growth of all axons into the ventral ramus suggests the presence of a strong, non-specific attraction.
The handedness and origin of supernumerary limb structures following 180° rotation of the chick wing bud on its stump
Authors: Javois Lorette C. , Iten Laurie E. 
Published: April 2021

ABSTRACT
The pattern of differentiated wing structures formed following 180° rotation of the undifferentiated wing bud tip on its base was examined in detail. These analyses were performed to determine the handedness and origin of the supernumerary structures which arise. In contrast to the variable classes of symmetric and/or asymmetric limb anatomies observed following the same operation with amphibian regeneration blastemas, wings of predictable handedness were observed. Both the graft and stump contributed cells to the supernumerary structures. These results are discussed in the light of two current models describing the developing chick limb and analysed diagrammatically within the framework of one of these models, the polar coordinate model.
Tetrasomy 16 in the mouse: a more severe condition than the corresponding trisomy
Authors: Debrot Sylvain , Epstein Charles J. 
Published: April 2021

ABSTRACT
Although an understanding of the phenotypic similarities and differences between individuals trisomic and tetrasomie for the same chromosome or chromosome segment is of considerable theoretical interest with regard to the relationship of the phenotypic features of aneuploid states to changes in the dosage of specific genes, the data obtainable from human cases of tetrasomy do not permit firm conclusions to be drawn. However, a mouse model system based on the intercrossing of animals doubly heterozygous for two Robertsonian translocation (metacentric) chromosomes with monobrachial homology can be used to generate both tetrasomie and trisomic embryos simultaneously. With mice carrying the two metacentric chromosomes, Rb(11.16)2H and Rb(16.17)32Lub, which share chromosome 16 in common, embryos with tetrasomy 16 and trisomy 16 have been generated. The rate of non-disjunction in both males and females was 34 to 36 %, and the observed overall frequency of tetrasomies in embryos up to 10 days of age was 3·3 %, very close to the expected 3·1 %. Although trisomy 16 and tetrasomy 16 embryos could not be distinguished by size from one another or from diploid embryos at the sixth day of gestation, the tetrasomy 16 embryos were very small and delayed in development at day 10 and clearly distinguishable from the trisomics. Fusion of the anterior neuropore had not occurred, rotation of the embryo was incomplete, and somite formation was retarded. By day 12, all of the tetrasomy 16 embryos were either dead or dying. By contrast, virtually all trisomy 16 embryos were alive at day 10, although about 60 % were retarded in development. The same was also the case on day 12 for trisomy 16 embryos obtained from mothers that were naturally mated. However, super ovulation of the mothers, which caused a doubling of the number of implants, resulted in a significant decrease in the frequency of trisomy 16 embryos and possibly of tetrasomy 16 embryos as well. This finding is consistent with the suggestion that the viability of aneuploid embryos, which may be at a proliferative disadvantage, is highly dependent upon intrauterine conditions. These exogenous factors notwithstanding, it is clear that tetrasomy 16 has much more deleterious effects on embryonic development than does trisomy 16 and that four doses of the genes on chromosome 16 result in developmental derangements greater than are produced by three doses of the same genes.
Non-random spatial arrangement of clone sizes in chimaeric retinal pigment epithelium
Authors: Schmidt Günter H. , Wilkinson Maureen M. , Ponder Bruce A. J. 
Published: April 2021

ABSTRACT
Clonal analysis of whole-mount preparations of entire retinal pigment epithelium (RPE), using SWR↔C57BL/6JLac and DDK↔C3H/Bi mouse aggregation chimaeras in which one of the two parental components predominated, revealed a markedly non-random spatial arrangement of patch (clone) sizes. Single-cell and small patches predominated in an area around the optic nerve head while large patches occurred most frequently near the periphery. Mechanisms are discussed which may explain these results. Patch size frequency distributions were concave and skewed. Singletons were the most frequent size class, but a wide range of sizes and a smaller number of much larger patches were also always found. The results preclude the use of statistical methods previously employed to calculate clone sizes from the geometric means of observed patch sizes. Instead, the median and interquartile range may provide the best summary of the observed patch size frequency distributions. Our findings support a stochastic model of tissue growth.
Interaction between the leg and surrounding thorax in the beetle
Authors: French Vernon 
Published: April 2021

ABSTRACT
Interactions between the insect leg and surrounding thoracic epidermis were studied in the beetle, Tenebrio, by grafting the entire larval prothoracic leg into the metathoracic leg site in various orientations.
Control grafts simply heal, but A/P reversed grafts lead to regeneration of supernumerary legs of host orientation in A and P positions. M/L reversed grafts also give supernumeraries, again with host orientation but in M (or MP) and L (or LA) positions. The differences in structure between adult prothoracic and metathoracic legs allow the origin of these super-numeraries to be analysed at coxa and tarsus level. The A/P supernumeraries are consistent and complementary in structure, of host origin on the host side and graft origin on the graft side, and with the borders in apparently constant midmedial and midlateral positions. The M/L super- numeraries, however, are variable and often non-complementary in structure. The results of the A/P and M/L reversals are similar to those found at a more distal level in Tenebrio legs and the legs of several hemimetabolous insects, suggesting that the arrangement of positional values and A and P compartments extends from the epidermis of the leg onto the surrounding thorax.
The results of a 180° rotation of the entire leg, however, differ from those found at a more distal level in that the grafted leg rarely derotated and two (or occasionally one or three) supernumeraries are formed in a wide variety of positions, some with constant and others with variable orientation. These results are not readily explained by current models of insect leg formation and regeneration.
Distribution of fibronectin, laminin and entactin in the environment of migrating neural crest cells in early mouse embryos
Authors: Sternberg J. , Kimber S. J. 
Published: April 2021

ABSTRACT
The distribution of the extracellular matrix molecules fibronectin, laminin and entactin was studied in frozen sections of -day mouse embryos in order to relate their presence to neural crest cell migration. It was found that all three components were present in basement mem-branes, laminin and entactin being mainly restricted to these. Fibronectin was present at high levels in basement membranes and extracellular spaces throughout the embryo, including the regions of neural crest cell migration. Fibronectin is known to affect migration in a variety of cell systems, so its presence in the.embryo at the time of migration may indicate that it is influencing cell movement. This influence is likely to be via the cell surface through interactions with other matrix components such as glycosaminoglycans, and possibly entactin and laminin.
Comparison of the effects of vitamin A on limb development and regeneration in Xenopus laevis tadpoles
Authors: Scadding S. R. , Maden M. 
Published: April 2021

ABSTRACT
The purpose of these experiments was to compare the effects of vitamin A on developing and regenerating limbs in Xenopus laevis tadpoles. Each tadpole had one hindlimb amputated to induce regeneration while the contralateral developing limb was left intact. Tadpoles at stages 50 through 54 were treated by immersion in retinol palmitate at doses ranging from 0·3 to 75i.u.ml−1, for periods ranging from 1 to 14 days. Developing limbs usually became hypomorphic as a result of the treatment, with results varying with stage and treatment from slight phalange derangements to total disruption of pattern, or complete inhibition of limb development. Regenerating limbs gave a variety of responses including hypomorphic regeneration, proximodistal or anteroposterior duplication of skeletal elements, or complete suppression of regeneration. The response to retinol palmitate of developing limbs was clearly different from regenerating limbs. Hypotheses which might explain the results were discussed and a hypothesis which proposed a dual action of vitamin A affecting both the cell cycle and the mechanism of pattern regulation was proposed.