bluuebunny/crossref_metadata_2025_split huggingface dataset:
Teratogenic Effects of Trypan Blue on Amphibian Embryos
Authors: Waddington C. H. , Perry M. M. 
Published: April 2021

ABSTRACT
Trypan blue, at concentrations around 0·025 per cent., was allowed to act on cleavage, gastrula, and early neurula stages of Xenopus, Axolotl, and Triturus alpestris and palmatus for various periods (about 24 or 48 hours). A variety of abnormalities were produced, of which the most striking were: (a) Oedema, (b) Microcephaly, (c) Prevention of elongation of the tail bud. (d) Vacuolation and swelling of the epidermal cells and fusion of the epidermis to the mesoderm, (e) Degeneration of the neural tissue (and to a lesser extent of the mesoderm) with appearance of vacuoles in the cells, (f) Suppression of gastrulation. (g) Mesodermalization of the notochord, similar to that produced by lithium. It seems unlikely that all these effects are consequences of one single original action. Some of the abnormalities (particularly (d) and (e), and to a lesser extent (b) and (g)) can be produced when the exposure to the dye occurs after gastrulation. In view of the lithium-like effect, Professor S. Ranzi of Milan has tested the action of trypan blue on the viscosity of protein solutions and their resistance to the action of urea, and found that it behaves similarly to other ‘vegetalizing’ agents. The incidence of these types of abnormality differs in the different amphibia investigated, as it also appears to do in the various stocks of mice which have been studied.
Analysis of the Determination of the Olfactory Placode in Amblystoma punctatum
Authors: Haggis Alex J. 
Published: April 2021

ABSTRACT
This study deals with the tissue factors engaged in the induction of the nasal organs in embryos of Amblystoma punctatum. Isolations and heterotopic transplantations of a large area of head ectoderm, including all the nose primordium of one side, demonstrate that the nose primordium is not determined before stage 21. By unilaterally excising nasal primordia, and either allowing the surrounding head ectoderm to heal over the wound, or replacing the excised primordium with anterior flank ectoderm from embryos at stages 13 to 25, it was demonstrated: (1) that heterotopic head ectoderm of all the stages studied is competent for nose formation, (2) that anterior flank ectoderm from stage 13 is able to react to nose-inducing stimuli, while (3) anterior flank ectoderm from stages beyond 14 no longer has this ability. The nose competence of heterotopic head ectoderm progressively decreases with increasing age. Transplantations of competent ectoderm in place of the excised nasal primordium at stages 15 to 27 show that nose-inducing capabilities are retained within the nasal region until the latest stages studied here. In some instances, early flank ectoderm, grafted into the nose region, was induced to form a brain fragment associated with a nasal organ. The latter was evidently induced secondarily by the former. Isolates of the prospective nasal ectoderm, previous to stage 21, differentiate a nose only if part of the adjacent forebrain anlage is included in the explants. Removal of the presumptive forebrain, with or without the underlying archenteron roof, could result in (1) complete absence of noses if the telencephalon is absent, (2) absence of one nose if the cerebral hemisphere is absent or very small, or (3) synrhiny or monorhiny if the forebrain is a small medial vesicle. The removal of the anterior one-seventh of the archenteron roof alone did not directly affect the number of noses present but tended to produce hypomorphic forebrains which in turn were associated with subnormal nose formations. The capability of prospective forebrain and the most anterior portion of the archenteron roof to induce nose was tested by wrapping these tissues, separately or together, in competent ectoderm. Nose inductions occurred only in those explants which contained brain, whether mesoderm was present or not. On the other hand, ectodermal explants enclosing head mesoderm alone showed no inductions. The frequency of nose inductions in explants containing presumptive forebrain was much higher than in those with mesoderm in addition to brain. Mesenchyme seemed to prevent rather than promote nose induction. The data taken together support the view that inductive stimuli emanating from the prospective forebrain are solely responsible for the emergence of the olfactory organs.
Differentiation and Metamorphosis of the Imaginal Optic Glomeruli in Drosophila
Authors: Shatoury H. H. El 
Published: April 2021

ABSTRACT
A description has been given of the differentiation and metamorphosis of the optic glomeruli. The giant ganglion cells of the larval brain degenerate at the end of the third instar after differentiation to the imaginal brain primordia is completed. The outer eye glomerulus was found to differentiate from the brain and not from the optic bud. The ‘fenestrated zone’ of the outer eye ganglion is an artefact, and develops from the histolytic products of the larval tissues in the head. The condition in the mutant eyeless is discussed.
Régénération du tissu musculaire strié dans des pertes de substance expérimentales de l’œsophage chez le chien
Authors: Picard D. , Henry E. , Cotte G. , Inglesakis J. A. 
Published: April 2021

ABSTRACT
When part of the dog’s thoracic œsophagus is surgically removed, and the defect is covered by a graft of pericardium, sutured to the adventitia without drawing together the edges of the wound, there occurs a very rapid reconstitution of the striated muscle tunic. The regeneration involved in this reconstitution occurs exclusively by a process of outgrowth, which initially gives rise to thin strands of little differentiated muscle, growing rapidly in length. These observations, made on the region of junction which can confidently be declared to be free from pre-existing musclefibres or fragments of muscle-fibres, throw doubt on the existence of the mode of regeneration called ‘discontinuous’, particularly on muscle-fibre neogenesis by differentiation of mesenchyme in situ. On the contrary, they support the opinion of Pfuhl, of Clark, and of Adams, Brown, & Pearson, that regeneration of mammalian striped muscle occurs exclusively by ‘continuous’ outgrowth. In these experiments, besides the immediate regeneration which re-establishes muscular continuity, there is a delayed outgrowth (lasting up to 7| months). We do not know the significance of this: it may be the consequence of continuous micro-trauma from the sutures, or it may be a very slow perfection of the anatomical and functional reconstitution of the muscular tunic.
Cell proliferation during morphogenetic change; analysis of frontonasal morphogenesis in the chick embryo employing DNA labeling indices
Authors: Minkoff Robert , Kuntz Amy J. 
Published: April 2021

ABSTRACTThe role of cell proliferation was analyzed in the chick embryo system employing DNA labeling indices during the invagination of the olfactory placode and the development of the lateral and medial nasal processes. Chick embryos were labeled for 1 h with [3H]thymidine and processed histologically and autoradiographically. The percentage of labeled mesenchymal cells in delineated areas within and adjacent to the nasal processes was determined. From analysis of labeling indices of each area at successive developmental stages, it was concluded that cell proliferation of mesenchyme, as measured by DNA labeling indices, did not appear to increase during the formation of the nasal processes, and that cell proliferation actually declined during the later stages of nasal process formation.Differences were also found between the labeling indices of the mesenchyme of the nasal processes as compared to that of adjacent areas. These differences tended to become greater as development progressed. In all of the areas studied, cell proliferation declined during the later stages of development but the magnitude of the decline was greater in the areas adjacent to the nasal processes. Differential rates of decline, rather than acceleration of cell proliferation, therefore, appears to be operative as a morphogenetic mechanism during early primary palate formation.
Development of interspecific hybrids ofMus
Authors: West John D. , Frels William I. , Papaioannou Virginia E. , Karr James P. , Chapman Verne M. 
Published: April 2021

ABSTRACTArtificial insemination has been used to produce interspecific mouse hybrids. Mus musculus × Mus cervicolor cervicolor hybrids failed to complete more than a few cleavage divisions but both M. musculus × M. dunni and M. musculus × M. caroli hybrids completed preimplantation development. These hybrid embryos are heterozygous for various X-linked enzymes and may provide a useful genetic system for studying X-chromosome inactivation during early development. Further development of M. musculus × M. caroli hybrids was studied: several completed foetal development; a few survived to maturity but none has yet reproduced.
Embryonic malformations in rats, resulting from maternal diabetes: preliminary observations
Authors: Deuchar Elizabeth M. 
Published: April 2021

ABSTRACTDiabetes mellitus was induced in female Wistar rats by injections of either alloxan or streptozotocin, and their embryos were found to have significantly higher incidences (7·5%) of brain and heart abnormalities (non-closure of neural folds, and deformities of heart chambers) at mid-gestation than controls (2·2%). There were also increased numbers of resorptions (25% in diabetic animals: 7·2% in controls). Both drugs produced similar abnormalities. External and X-ray examination of 488 foetuses from streptozotocin-treated animals at 20 days showed eight cases of exomphalos, two cases of micrognathia with tongue protrusion, and 34 cases of incomplete sacral ossification. This last deformity occurred also in foetuses of mildly diabetic animals, and has been seen occasionally in infants of human diabetic mothers. Other evidence suggests that skeletal deformities may be due to hyperinsulinism in the foetuses of diabetic mothers. Even a mild or pre-diabetic condition may set the foetus at risk.
DNA synthesis during the first stages of anterior regeneration in the polychaete annelid Owenia fusiformis (dedifferentiation and early phases of differentiation)
Authors: Marilley Monique , Thouveny Yves 
Published: April 2021

ABSTRACT
We have analysed DNA synthesis in early phases of regeneration in a marine Polychaete Annelid, Owenia fusiformis. The length and efficiency of the prereplicative phase was found to vary with the diurnal rhythm of activity of the animal; that is, it depends on the initial state of the cell population at the moment of the onset of proliferative stimulation. When animals were operated on at 12 a.m., the duration of the prereplicative phase of the first cells stimulated to proliferate was found to be 12 h. The remaining cells entered the S-phase progressively in waves until the 3rd day following amputation when nearly 100% of the blastema cells were stimulated. At that time the cell-cycles of these dividing cells were found to be highly synchronized. Blastema differentiation takes place on the 4th day and is initiated by stomodeum formation. During the differentiation phase, DNA synthesis is restricted to small areas of the regenerating part. The system described is viewed as a new instrument for investigating the control of the cell cycle in synchronized and subsequently differentiating tissue cells.
In vitro development of inner cell masses isolated immunosurgically from mouse blastocysts: II. Inner cell masses from 3·5- to 4·0-day p.c. blastocysts
Authors: Hogan Brigid , Tilly Rita 
Published: April 2021

ABSTRACT
This paper describes the development in culture of inner cell masses isolated immunosurgically from C3H/He mouse blastocysts immediately after collection between 3 ·5 and 4 ·0 days p.c. By 24 –48 h most of the inner cell masses isolated from half-expanded blastocysts, and about 50 % of those from expanded blastocysts, regenerate an outer layer of trophecto-derm-like cells and so resemble mini-blastocysts. With further in vitro culture these structures attach to the substratum and give rise to trophoblast-like giant cells, together with clusters of parietal endoderm cells or inner cell masses surrounded by visceral endoderm.
Many of the inner cell masses from the remaining expanded blastocysts develop into floating structures with an outer layer of endoderm cells, and by 7 days consist of a large fluid filled cyst surrounding a collapsed vesicle of epithelial cells. Mesodermal cells line the cysts and form numerous blood islands. When mechanically disrupted, and grown as attached sheets of cells, these cystic structures give rise to patches of trophoblast-like giant cells similar to those described in the previous paper.
These results suggest that the inner cell mass of normal mouse blastocysts contains cells which are capable of giving rise to trophoblast in culture.
A method for isolating uncontaminated nuclei from all stages of developingXenopus laevisembryos*
Authors: Farzaneh F. , Pearson C. K. 
Published: April 2021

ABSTRACTA method for isolating nuclei from Xenopus laevis embryos has been developed. This procedure enables the isolation of nuclei, free from contamination with yolk and pigment granules, at all stages of embryonic development. Using this method the nuclear yield is 60– 70% of the estimated number of cells in the embryo. The DNA, RNA, histone and non-histone protein content of these nuclei during embryogenesis (from early cleavage to the swimming tadpole stage) has been measured.
In vitro studies of mouse embryos bearing mutations in the T complex: t6
Authors: Wudl Linda R. , Sherman Michael I. 
Published: April 2021

ABSTRACTCultured blastocysts homozygous for the t6 mutation lose their inner cell mass within a few days of attachment to the culture dish. At about the same time it becomes apparent that putative t6-mutant trophoblast cells and their nuclei fail to enlarge to the degree of their normal counterparts. These abnormalities in mutant embryos are reflected by an abrupt drop on the seventh equivalent gestation day in the rate of increase of β-glucuronidase activity. The failure of t6/t6 trophoblast nuclei to enlarge normally appears to be due partially to endoreduplication at a slower rate than normal trophoblast nuclei and partially to pre-mature cessation of DNA synthesis. Analyses indicate that this abnormality is not reversed when mutant embryos are placed in chimeric association with normal ones. Trophoblast outgrowths from mutant and normal trophectodermal vesicles are similarly distinguishable by differences in outgrowth and nuclear size as well as DNA content and synthesis. Despite the fact that t6/t6 embryos and trophectodermal vesicles are phenotypically different from normals from early times in culture, the trophoblast cells in the mutant structures acquire and continue to produce two enzymes characteristic of trophoblast differentiation, Δ 5,3 β -hydroxysteroid dehydrogenase and plasminogen activator.On the basis of these and previous observations, we propose that the primary effect of the t6 mutation is to cause a metabolic lesion which kills inner cell mass cells relatively quickly but which has a more gradual effect upon trophoblast cells. The fact that phenotypically recognizable t6/t6 trophoblast cells can survive for several days before dying makes this a potentially useful system in which to search for the t6 gene product(s).
The Penetration of Phosphate into Whole and Dissected Amphibian Embryos
Authors: Thomason Doreen 
Published: April 2021

ABSTRACT
Embryos of Siredon mexicanum and Xenopus laevis were shown, by the use of 32P, to take up small but measurable amounts of phosphate from the culture medium. The rate of uptake was higher in embryos than in unfertilized eggs, and was related to the stage of development. The rate was proportional to the concentration of phosphate in the medium. Spontaneously occurring microcéphalie embryos took up much more phosphate than normal embryos. Injured embryos and dissected fragments of embryos took up more phosphate than intact embryos. Dissected neurulae took up more phosphate than dissected blastulae, and half-gastrulae took up more than either. Vegetative fragments of blastulae took up more phosphate than animal fragments, particularly towards the end of the 6-hour period studied. Ventral fragments of gastrulae took up the same amount of phosphate as dorsal halves during the first 2 hours after cutting, but subsequently took up more. The phosphate uptake of dorsal fragments of neurulae was at first the same as that of ventral fragments, but from 4 to 6 hours after cutting was about twice as rapid. 10 – 4 M p-dinitrophenol had a slight inhibiting effect on uptake of phosphate by whole embryos, counterbalanced by adsorption of 32P on killed cells. The phosphate uptake of fragments was cut down by the inhibitor to about one-half to one-third the level of the controls.
The Embryology of Cortisone-induced Cleft Palate
Authors: Walker B. E. , Fraser F. C. 
Published: April 2021

ABSTRACT
Cortisone treatment causes cleft palates by interfering with the development of the condition within the palatine shelves that forces them to change their alignment from the vertical to the horizontal plane. The consequent delay in shelf movement, the apparent inability of the shelves to grow wider without the stimulus of being fused, and the continued increase in head width, result in a palate in which the shelves are too far apart to touch and fuse when they finally become horizontal.
The strain difference between C57BL and A/Jax mice in their susceptibility to the teratogenic action of cortisone is due in part to the earlier closing of the palate in C57BL embryos, and in part to the lesser inhibition of shelf movement in C57BL embryos as compared to A/Jax embryos. These differences suggest that the C57BL maternal-embryo complex has a more efficient metabolic system for developing palate shelf movement than exists in the A/Jax strain.
The time of action of three mutations affecting Drosophila eye morphogenesis
Authors: Ransom Robert 
Published: April 2021

ABSTRACT
Histology and clonal analysis are used to look at the time of action of the mutant Drosophila genes eyeless2, eyeless dominant and sine oculis. The findings suggest that eyeless dominant has its effect during the first two larval instars, whilst eyeless2 and sine oculis act during the third larval instar.
Differential mitosis and degeneration patterns in relation to the alterations in the shape of the embryonic ectoderm of early post-implantation mouse embryos
Authors: Poelmann R. E. 
Published: April 2021

ABSTRACTThe shape of the embryonic ectoderm of early post-implantation mouse embryos changes greatly in the period of 6 ·2–7 ·3 days post coitum. The subcellular morphology of the embryonic ectoderm remains unchanged, except in the primitive-streak region. Cell kinetics differ between ectodermal regions. These differences may be related to the changes in the shape of the ectoderm. The increase in cell number in the lateral ectoderm (the prospective surface ectoderm) exceeds that in the frontal ectoderm (the future neurectoderm). This is not due to differences in the duration of the cell cycle. It can be explained, however, by the occurrence of different relative numbers of dividing and non-dividing cells. These numbers vary between the two regions. The percentage of non-dividing cells in the frontal ectoderm may reach 45, whereas in the lateral ectoderm this percentage is not higher than 15. Autoradiography in tritiated thymidine-treated embryos combined with the mitotic indices gave us all of the parameters necessary to present a model capable of clarifying the growth of the ectoderm during gastrulation, as well as the changes in the shape of the ectoderm.
Origin and cytochemistry of the animal dimple granules inDiscoglossus pictus(Anura) eggs
Authors: Andreuccetti Piero , Campanella Chiara 
Published: April 2021

ABSTRACTAt the centre of the animal hemisphere of the 1000μm ovarian oocytes of Discoglossus pictus there is the germinative area, a slightly depressed disc, 700 μm wide. During the passage of the oocyte through the oviduct this area becomes invaginated to form the ‘animal dimple’, which is the only site where successful sperm entrance can occur. Granules (G) with a central electron-dense core and a peripheral portion containing sparse fibrous material are found in the peripheral cytoplasm of the animal dimple.The origin and the cytochemistry of G’s have been investigated. G’s originate from Golgi complexes located in the peripheral cytoplasm of the germinative area only. Recently formed G’s migrate to the oocyte cortical region, where vesicles appear to participate in G’s maturation. The core of G’s can be digested by pronase, is negative to a test for acid phosphatase detection, and contains a few polysaccharide complexes. In view of their origin from Golgi complex, their location in the oocytes and their exocytosis upon activation, G’s seem to correspond to the typical cortical granules of Anurans. However, they appear to have a macromolecular content different from that of the cortical granules.
Formation of marrow cavity and ossification in mouse limb buds grownin vitro
Authors: Johnson D. R. 
Published: April 2021

ABSTRACTExplanted mouse limb buds aged 12, 13 or 14 days cultured for 9 days in vitro failed to develop a marrow cavity or show endochondral ossification.Explants aged 15 days developed a marrow cavity and showed signs of endochondral ossification. The periosteum in these limbs was perforated and laminated and cells appeared to be passing between the laminae to populate the marrow cavity. This suggests that there is a periosteal contribution to the bone marrow even in the absence of a blood supply.
The initiation of pupariation in Drosophila : dependence on growth of the imaginal discs
Authors: Simpson P. , Berreur P. , Berreur-Bonnenfant J. 
Published: April 2021

ABSTRACT
Regeneration was induced in the imaginal discs in situ following lesions caused by heatsensitive cell-lethal mutations. A clonal analysis of this event demonstrated that the subsequent delay in pupariation was correlated with the amount of extra growth that occurred during the regeneration. Pupariation of heat-treated gynandromorphs bearing the mutations was also retarded, and the duration of larval development increased with greater amounts of mutant tissue, it was therefore correlated with the extent of the lesions in the imaginal discs. Elimination of entire imaginal discs, or the presence of very small amounts of lethal tissue, did not result in prolonged larval life.