bluuebunny/crossref_metadata_2025_split huggingface dataset:
An experimental investigation into the possible origin of pancreatic islet cells from rhombencephalic neurectoderm
Authors: Andrew Ann , Kramer Beverley 
Published: April 2021

ABSTRACTTo determine whether or not any pancreatic islet cell type arises from rhombencephalic levels of neurectoderm, lengths of presumptive rhombencephalon (containing potential neural crest) of Black Australorp chick embryos at 6-to 9-somite stages were replaced iso-topically and isochronically by neural tube of Japanese quail embryos. Some transplants included mesencephalic regions. In some cases various levels of the rhombencephalon were deleted and not replaced.The quail nuclear marker was detected in cranial ganglia in operated embryos sacrificed at days of incubation and in enteric ganglia and cells accompanying some pancreatic nerves, in embryos killed at 7 days of incubation. This provided evidence of normal migration of crest cells from the grafts. Dopa was administered to the younger embryos, which were submitted to the formaldehyde-induced fluorescence procedure to demonstrate APUD (Amine Precursor Uptake and Decarboxylation) cells. No pancreatic APUD cells exhibited the quail nuclear marker. In 9-to 11-day embryos, A and B cells were identified by specific light and electron microscopic features. None showed the quail marker. The marker was also absent from those D cells seen and from cells of an as yet unidentified type, but not enough of these were found to warrant a conclusion. All islet cell types were found in embryos from which various levels of the rhombencephalon had been deleted.It is concluded that at least A and B islet cells are not derived from the rhombencephalic neurectoderm and probably not from mesencephalic levels. Their most likely origin remains the endoderm, which was the accepted source until recently.
The development of hepatogenic potency in the endoderm of quail embryos
Authors: Fukuda Sumiko 
Published: April 2021

ABSTRACT
Hepatogenic potency of the endoderm is detectable in the anterior half of the endoderm of quail embryos older than 2-somite stage when endodermal fragments are cultured with or without heterologous chick mesenchymes, in the coelomic cavity of 3-day chick embryos. On the other hand, the posterior half of the endoderm never has hepatogenic potency. The hepatogenic potency of the endoderm is gradually stabilised with increasing age. However, expression of hepatogenesis can be affected when the endoderm is associated with inductively active digestive tract mesenchymes.
Mesenchyme taken from the presumptive cardiac region (‘cardiac’ mesenchyme) of chick embryos is necessary for the uncommitted anterior endoderm to acquire hepatogenic potency, and this effect is specific for the ‘cardiac’ mesenchyme. The ‘cardiac’ mesenchyme, however, fails to induce hepatic epithelium in the allantoic endoderm, which can differentiate heterotypically when cultured in combination with digestive tract mesenchymes. The evidence presented in this study suggests that the effect of ‘cardiac’ mesenchyme on the acquisition of hepatogenic potency in the endoderm is limited.
Étude autoradiographique de l’incorporation de 14CO2 dans des gastrulas d’Axolotl
Authors: Tencer R. 
Published: April 2021

ABSTRACT
Regional incorporation of 14CO2 into Amphibian gastrulae has been followed by autoradiography. Differences in uptake of the tracer in different parts appear already in the early gastrula. These differences only affect the cytoplasm while the nuclei, heavily labelled, show very similar radioactivities. In the late gastrula, however, the nuclei show the same gradients of activity as the cytoplasm.
Interaction ectoderme-mésoderme dans la formation des invaginations uropygiennes des Oiseaux
Authors: Gomot Lucien 
Published: April 2021

ABSTRACT
The culture in vitro of the tail-bud of duck embryos aged 8,9, and 10 days permits the formation of uropygial invaginations (rudiments of the preen gland) that normally appear on the 11th day of incubation. The separation of the various tissues of the tail-bud of 10-day duck embryos and their culture in association with some other duck embryonic tissues has made it possible to locate, at this stage, the ‘organizer’ of the preen gland in the superficial stratum of the dermis. The formation of the glandular invaginations results from an interaction between ectoderm and mesoderm, in which, at the beginning, only the mesoderm is specific. The ectoderm of chick embryos and rabbit embryos is able to react to contact with this mesoderm in the same way as the ectoderm of duck embryo.
The Formation of the Second Maturation Spindle in the Eggs ofLimnaea, Limax, andAgriolimax
Authors: Raven Chr. P. , Escher Frouke C. M. , Herrebout W. M. , Leussink J. A. 
Published: April 2021

ABSTRACTEgg maturation has been studied in Agriolimax reticulatus, Limax flavus, and Limnaea stagnalis with special regard to the formation of the second maturation spindle. In the three species the second maturation spindle arises by direct transformation from the deep centrosphere of the first maturation amphiaster. In Agriolimax reticulatus and Limax flavus there is a pair of centrioles moving apart to opposite poles of the developing spindle. In Limnaea stagnalis there is only one centriole, which remains undivided and moves as a whole to the outer pole of the spindle. The developing spindle in Agriolimax and Limax is symmetrical and gets an aster at both ends, arising in the cytoplasm outside the original centrosphere. The developing spindle of Limnaea stagnalis is asymmetrical, egg-shaped, and aster formation occurs at its pointed outer end only. The inner aster of the second maturation spindle in Limnaea is provided by the sperm aster, which fuses secondarily with the blunt inner end of the spindle. There are some indications that the fusion between these two structures is accompanied by a certain cytochemical activity in the region of fusion. The sperm aster in Limax flavus appears some time after the extrusion of the first polar body; it does not fuse with the second maturation spindle but disintegrates by vacuolization soon after the extrusion of the second polar body. In Agriolimax reticulatus no sperm aster has been observed. In the three species the dyads apply themselves closely against the centrosphere but do not penetrate into it. In Agriolimax and Limax they lie as a compact group on one side against the equatorial region of the developing spindle. In Limnaea they become arranged into an irregular ring, which encircles the outer pole of the developing spindle and gradually shifts to the equatorial region of the spindle. In the three species the dyads only penetrate into the spindle when the latter has been completely formed. The results are discussed with reference to the relationships in the Pulmonates in general. It is concluded that the sperm aster is a more or less rudimentary structure in this group. In Limnaea the sperm aster has taken on a new function in the mechanism of polar body extrusion. The primary cause of the atypical development of the second maturation spindle in Limnaea is, presumably, the precocious inactivation of the egg cyto-centre, which divides no more after the completion of the first maturation division.
Regional Differences in Catheptic Activity inXenopus laevisembryos
Authors: Deuchar E. M. 
Published: April 2021

ABSTRACTThe total catheptic activity per embryo in X. laevis increases during gastrulation and early neurulation, decreases slightly during late neurulation, then increases again at the early tail-bud stage. When dorsal and ventral parts of gastrulae, neurulae, and tail-bud stages are compared, the catheptic activity per unit dry weight is highest in dorsal parts, but the absolute activity per part, and the activity per cell, are highest in ventral parts of the embryos. The catheptic activity is increased in the presence of 0 0024 M cysteinehydrochloride. The yolk platelets, separated from other cell-constituents by centrifuging, carry a considerable proportion of the catheptic activity, though not as much as the supernatant fraction. The possibilities that the catheptic activity gives rise to increased concentrations of free amino acids and that it assists in yolk breakdown are discussed.
Effect of a Leucine Analogue on Incorporation of Glycine into the Proteins of Explanted Chick Embryos
Authors: Schultz Phyllis w. , Herrmann Heinz 
Published: April 2021

ABSTRACT
Amino acid analogues have been observed to give rise to abnormal forms of development of chick and amphibian embryos (Herrmann, 1953; Rothfels, 1954; Waddington & Sirlin, 1954; Feldman & Waddington, 1955; Herrmann, Rothfels-Konigsberg, & Curry, 1955). Assuming that these disturbances may be due to interference with the utilization of amino acids for protein formation, we have attempted an analysis of this effect by comparison of the protein contents and of the uptake of glycine into the proteins of chick embryo explants in the presence and absence of amino acid analogues. The results of such experiments are reported in this paper.
On Regeneration after the Amputation of Abnormal Structures
Authors: Newth D. R. 
Published: April 2021

ABSTRACT
The bilateral removal of the posterior neural folds of axolotl neurulae may lead to the development of larvae in which a greater or lesser length of the ventral fin of the tail between the cloaca and a point just short of the tail-tip is missing. In other cases regulation permits the development of a normal-looking tail. The later amputation of such ‘normal’ tails, or of defective ones where the plane of amputation lies anterior to the defective region, is followed by the formation of normal regenerates. The amputation of defective tails where the plane of amputation passes through a region lacking ventral fin is followed by the formation of a regenerate lacking ventral fin as far posteriorly as a point just short of the tail-tip. The presence or absence of a ventral tail-fin in the regenerate depends upon its presence or absence in the plane of amputation, and is not otherwise related to the degree of abnormality of primary urogenesis. Tails which have defective ventral fins and poorly developed somitic musculature (as a consequence of simultaneous removal of posterior neural folds and part of the posterior medullary plate) behave in regeneration as do those lacking ventral fin only, even where the plane of amputation passes through a region with deficient somites. The removal of the dorsal half of the tail-bud of embryos of R. temporaria may also be followed by almost normal urogenesis as a consequence of regulation. In most cases, however, the resulting tails are extensively defective lacking a region of the dorsal fin, parts of the spinal cord, and having poorly developed somitic musculature. In nearly every case the amputation of these tails was followed by the formation of a regenerate that was normal if the original tail was ‘normal’ or if the plane of amputation lay anterior to the region of the tail which lacked a dorsal fin. Where the plane of amputation passed through a region lacking dorsal fin the regenerate was formed without one. In a very small number of cases exceptional and defective regenerates were formed, either after a first or a subsequent amputation, where normal ones were to be expected. The occurrence and significance of these exceptions are discussed. It is concluded that the successful completion of normal primary urogenesis in amphibians is not a prerequisite of the formation of a normal regenerate. It remains possible that the formation of normal regenerates from abnormal tails involves regulative properties in the blastema. The need for representation of tail-fin at the plane of amputation if it is to be present in the regenerate is further confirmation of the departure of amphibian tail regeneration from the pattern established for the urodele limb.
Recherches sur l’action tératogène du refroidissement temporaire de l’œuf de Poule au cours de l’incubation
Authors: Ancel P. 
Published: April 2021

ABSTRACT
De très nombreux auteurs ont signalé les effets tératogènes de divers agents physiques sur l’œuf de Poule (incubation à des températures élevées ou basses, vernissage des œufs, secouage, prélèvement d’albumine, réalisation d’une fenêtre dans la coquille, radiations diverses, ultra sons etc.) avant ou pendant les premiers jours de l’incubation. Nous avons cherché à savoir si des malformations différentes de celles qui avaient été ainsi obtenues pouvaient l’être après la soixante-douzième heure de l’incubation. Nous avons choisi comme agent un choc thermique qui n’a pas d’action tératogène dans les premiers jours de l’incubation.
Cell Mixtures of Different Species and Strains of Cellular Slime Moulds
Authors: Bonner John Tyler , Adams Marcia Shaw 
Published: April 2021

ABSTRACT
The cells of various species and strains of cellular slime moulds have been mixed by making grafts at the aggregation stage and by thoroughly mixing the cells at the migration stage. Depending upon the strains used, varying degrees of cell compatibility or adhesion between the cells was observed. There was either (l)a complete separation of the strains; (2) a partial merger to form a double fruiting body, one standing on the sorus of the other; (3) a single fruiting body on which the pre-spores of both strains regrouped to form two cohesive blocks of cells within one sorus.
This regrouping phenomenon is also characteristic of many dissociated animal cells where partially or completely differentiated cells will regroup with their kind. It is suggested that the basis of this regrouping phenomenon is the result of an intermediate degree of surface compatibility—not so great as to produce a complete separation of the cells, and not so little as to permit a random intermingling of the cells.
A Note on the Effects of some Cytotoxic Substances on Amphibian Embryos
Authors: Waddington C. H. 
Published: April 2021

ABSTRACT
In connexion with the experiments of Jurand (1958) on the action of TEM on avian embryos, it seems worthwhile describing very shortly some observations on the effects of this substance, and also of Myleran, on early amphibian embryos. Bodenstein (1954 and earlier) has described some of the cytological results of the administration of various ‘radio-mimetic’ substances to amphibian embryos, including nitrogen mustards and TEM. The effects on the development of the eye were particularly considered, and they have also been discussed and illustrated by Töndury (1955). Two main types of damage were noted, the formation of giant cells, and of cellular degeneration accompanied by nuclear breakdown and the formation of deeply staining cytoplasmic lumps. The giant cells presumably arise from the suppression of cell-division followed by the formation of a restitution nucleus. These nuclei stain rather palely, and appear to be lacking in DNA. On the other hand, the cytoplasmic globules which are commonly met with appear to consist of RNA, and to indicate an over-production of that compound.
Experimental Tetraploidy in Newts 1
Authors: Fischberg M. 
Published: April 2021

ABSTRACT
A simple method has been devised for producing tetraploid newts by means of a ‘heat’ treatment. The eggs of T. palmatus (helveticus) and T. vulgaris were at different stages, varying from 3 hours to hours after artificial insemination, exposed to warm water of 34° –38°C. for a duration of 10–12 minutes. A temperature treatment of 35 ·6° –36·0° C. proved to be the most successful for the production of tetraploid embryos and larvae. Treatment at the stage when the first cleavage furrow closes at the vegetative pole was found to be the only effective one. The eggs contain at this stage two interphase nuclei. The described treatment causes up to 24 per cent, of all treated eggs, or up to 93·7 per cent, of all analysed newts to develop into tetraploids. The probable cytological mechanism which leads to tetraploidy is discussed. Factors which seem to be of importance for the production of tetraploidy in other amphibian species, and some important problems which might be investigated with the help of this method, are mentioned.
Intestinal Development
Authors: Coulombre Alfred J. , Coulombre Jane L. 
Published: April 2021

ABSTRACT
A description of chick duodenal morphogenesis is given. It is based on (a) quantitative measures of the change in size and shape of the duodenum, (b) a histogenetic study of the duodenal musculature, and (c) a quantitative description of changes in size, shape, and number of the duodenal villi throughout their development.
Correlation of these data on a developmental time-scale has led to the following hypotheses:
Mesenchymal cells are oriented by mechanical forces acting to distort a tissue. The orientation of smooth muscle is determined by the orientation of the premuscle mesenchyme in which it differentiates. In the wall of a hollow viscus such as the duodenum the contraction of the first layer of muscle to form will orient the remaining mesenchymal cells at right angles to itself, thus determining the orientation of the muscle-layers which subsequently differentiate. The duodenal villi are shaped by mechanical forces which act on the mucosa and which arise from epithelial expansion, on the one hand, and muscular contraction, on the other.
Genetical Studies on the Skeleton of the Mouse
Authors: Deol M. S. 
Published: April 2021

ABSTRACT
A pilot experiment by Weber (1950) established the fact that the minor skeletal variations universally present in strains of tame mice are also encountered in wild populations; and that the incidence of individual variants may differ widely from population to population. In the decade since Weber’s work many new variants have come to light, and it seemed desirable to repeat his observations on the more extensive range of variants now available. An opportunity to do so presented itself in 1956 when wild mice from various localities in the eastern U.S.A, became available for study.
Inherited Retinal Dystrophy in the Mouse: its Appearance in Eyes and Retinae Cultured in vitro
Authors: Lucas D. R. 
Published: April 2021

ABSTRACT
Certain strains of mice, such as C3H, exhibit a recessively inherited retinal dystrophy. This takes the form of a degeneration and complete disappearance of the visual cell layer; it begins on or about the 11th day of life and is nearly complete by the 19th day (Sorsby, Koller, Attfield, Davey, & Lucas, 1954). The process is remarkably uniform from litter to litter (Lucas & Newhouse, 1957).
An Ultra-Violet Light Method for Producing Haploid Amphibian Embryos
Authors: Selman G. G. 
Published: April 2021

ABSTRACT
For several years in this laboratory, ultra-violet light has been used to produce haploid amphibian embryos, sometimes to provide haploid nuclei for transplantation experiments, as in Pantelouris & Jacob (1958). The ultra-violet method gives a high proportion of haploids, is very simple and speedy to carry out and involves the use of only inexpensive apparatus. Our method and results are described here to help others choose between this and alternative methods such as the use of toluidine blue by Briggs (1952), or X-rays by Lehman (1955) and Rugh (1939). Other methods are reviewed in Fankhauser (1937) and Drebinger (1951).
Cell differentiation in a temperature-sensitive stalkless mutant of Dictyostelium discoideum
Authors: Amagai Aiko , Ishida Shuji , Takeuchi Ikuo 
Published: April 2021

ABSTRACT
A temperature-sensitive aggregateless and stalkless mutant was isolated from Dictyostelium discoideum NC-4. The mutant cells cannot aggregate at 27 °C, but aggregate and form normal fruiting bodies at 21 °C. When the temperature was shifted to 27 °C after aggregation at 21 °C, almost all of the cells in the aggregate differentiated into spores. Neither stalk cells nor stalk tubes formed at 27 °C. Inhibition of stalk formation was not lifted by addition of cyclic AMP.
Nevertheless, the proportion of prespore to total cells within the mutant slugs was normal, at both 21 °C and 27 °C. At 27 °C, a slug was transformed into a spherical cell mass at the end of migration, within which pre-existing prespore cells differentiated into spores. The remaining prestalk cells were then converted to prespore cells which later became spores. As the celltype conversion continued, formation of a spore mass resulted. The development of the mutant is thus consistent with the idea that the presumptive cell differentiation is directly related to the terminal cell differentiation.
During migration at 27 °C, the number of prestalk cells decreased in the anterior part of the slug but instead increased at the foot or the rear part, whereas the prestalk-prespore pattern remained normal at 21 °C. The fact that a normal proportion of prespore cells was maintained in spite of their deranged distribution at 27 °C indicates that the regulation of proportion is independent of the formation of pattern.
Growth and morphogenesis of the fibula in the chick embryo
Authors: Archer Charles W. , Hornbruch Amata , Wolpert Lewis 
Published: April 2021

ABSTRACT
The development of the avian fibula was studied both histologically and experimentally. It was found that from the onset of chondrogenesis, the fibula possessed a smaller diameter than the neighbouring tibia. The truncated growth of the fibula was a result of the loss of its distal epiphysis between stages 27– 31. This epiphysis subsequently became fused to the tibia and formed the fibulare of the tibiotarsus. The experiment of Hampé (1960) was repeated by inserting tantalum barriers into the limb between stages 18 and 23: this sometimes prevented the separation of the fibula distal epiphysis, thus giving rise to an elongated element. A similar result was obtained from grafts of polarizing region into the leg bud at stages 18– 20. It was concluded that there was no evidence for competitive interaction between the blastemata of the tibia and fibula. In addition, the differential growth in diameters between the tibia and fibula was largely a result of differential osteogenesis rather than chondrogenesis as previously thought.
Proportion regulation without pattern formation in Dictyostelium discoideum
Authors: Oyama Masakazu , Okamoto Koji , Takeuchi Ikuo 
Published: April 2021

ABSTRACT
When shaken in a glucose-albumin-cAMP medium, dissociated aggregative cells formed small clumps, in which both prespore and prestalk cells differentiated in essentially the same proportions as in a slug. Immunocytochemical staining of sections of such clumps revealed that the two types of cells showed no particular pattern of distribution, unlike the two-zoned prestalk-prespore pattern as observed in the slug.
Cells dissociated at stages later than the onset of aggregation always produced a constant proportion of prespore cells, irrespective of the initial proportion when transferred to the culture. Furthermore, prestalk cells fractionated from slugs and transferred to the culture restored almost the normal prespore proportion through conversion of the cell types, whereas proportion of unfractionated slug cells remained unchanged. We conclude from these findings that the normal prestalk-prespore pattern is not required for proportion to be regulated.