bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence inductrice de l’encéphale embryonnaire sur le développement du crâne chez le poulet: II. Influence de l’excision de la chorde et des territoires encéphaliques moyen et postérieur sur le développement crânien
Authors: Schowing Par Jean 
Published: April 2021

ABSTRACT
The inductive influence of the embryonic brain upon the development of the skull in the fowl. II. The effect of removal of notochord and of mid-and hind-brain material upon cranial development
The notochord and the mid-and hind-brain of chick embryos 48 h old were removed with the following consequences.
Excision of the notochord alone leads to a reduction of the basal plate and basioccipital. The other bones of the head are unaffected by the operation. Excision of the mesencephalon alone has a minor effect on the skull. Its action on cranial differentiation is weaker than that of the other parts of the brain. Excision of the rhombencephalon alone leads to a reduction of parietals, which disappear after excision of both mesencephalon and rhombencephalon. In both cases, the basal plate is reduced. Development fails completely if the notochord is excised with the brain tissue. If both rhombencephalon and anterior medullary tube are excised, the parietals are reduced and the lateral and dorsal parts of the occipital complex disappear. The basioccipital and basal plate are differentiated, but remain small. These experiments demonstrate that cranial vault differentiation depends on the brain and show the role of the notochord in the development of the cartilaginous cranial floor.
The effect of removing the polar lobe in centrifuged eggs of Dentalium
Authors: Verdonk N. H. 
Published: April 2021

ABSTRACT
Classical evidence for the existence of morphogenetic substances was provided by experiments with spiralian eggs possessing a polar lobe: Ilyanassa (Crampton, 1896; Clement, 1952, 1956, 1962); Dentalium (Wilson, 1904); Chaetopterus (Tyler, 1930); Sabellaria (Hatt, 1932; Novikoff, 1938); and Mytilus (Rattenbury & Berg, 1954). Eggs from which the polar lobe had been removed developed into embryos with specific abnormalities. In Dentalium, after removal of the polar lobe at the trefoil stage, a trochophore larva is formed without post-trochal region and apical tuft. Removal of the polar lobe at second cleavage causes a larva without post-trochal region, but with an apical tuft. Wilson concluded that specific cytoplasmic materials essential to the formation of the apical tuft are contained in the first but no longer in the second polar lobe.
Mise en évidence du rôle inducteur de l’encéphale dans l’ostéogenèse du crâne embryonnai re du poulet
Authors: Schowing Par Jean 
Published: April 2021

ABSTRACT
Nos expériences d’excision des différents territoires encéphaliques (Schowing, 1959, 1961, 1967) mettent en évidence l’importance du rôle des structures nerveuses dans la différenciation du squelette crânien. Le mécanisme de cette action inductrice, ainsi que la nature de l’inducteur, est mal connu.
Influence inductrice de l’encéphale embryonnaire sur le développement du crâne chez le Poulet: I. Influence de l’excision des territoires nerveux antérieurs sur le développement crânien
Authors: Schowing Par Jean 
Published: April 2021

ABSTRACT
The inductive influence of the embryonic brain upon the development of the skull in the fowl. I. The effect of removal of anterior neural material upon cranial development
Chick embryos 48 h old and possessing 10-20 somites were subjected to the removal of different parts of the brain.
Removal of the prosencephalon alone leads to a reduction of the frontal bones. The other bones of the skull are unaffected. The frontals disappear if both prosencephalon and mesencephalon are excised. Both frontal and parietal bones disappear if the brain is completely removed. In this case, the squamosals alone remain, but are reduced. The cranial floor is also changed. If both brain and anterior medullary tube are excised, not only the frontals and parietals disappear, but also the supraoccipitals. At the same time, the cranial floor is reduced. Depending upon the presence or absence of the face, the palatines are normal or reduced and the parasphenoidal rostrum is present or absent. In the absence of notochord, the cranial floor is reduced or lacks some pieces, particularly basisphenoid and basioccipital. The cranial vault depends directly on the brain which is necessary for its differentiation. The palatines and the parasphenoidal rostrum are independent of nervous tissue but both depend upon the presence of the face. The basisphenoid and the basioccipital are influenced by both neural tube and notochord. This suggests that the latter has an important role, worthy of further study.
Ultracentrifugal and electrophoretic analysis of the water-soluble fraction of chick embryo yolk
Authors: Carinci P. , Manzoli-Guidotti L. 
Published: April 2021

ABSTRACT
Ultracentrifugal and electrophoretic analysis of chick embryo yolk water-soluble fraction (WSF) has been carried out using fertile non-incubated eggs and at 10, 15 and 21 days incubation. Ultracentrifugal and electrophoretic analysis of WSF globulins has been carried out at the same incubation stages. The ultracentrifugal and electrophoretic patterns of both the WSF and its globulin components at 10 days incubation are very similar to those observed in non-incubated eggs. Ultracentrifugal and electrophoretic patterns at 15 and 21 days incubation undergo marked changes due to the appearance of egg-white proteins in the yolk. The significance of these findings in relation to embryogenesis is discussed.
Analysis of the development of the nervous system of the zebrafish, Brachydanio rerio: I. The normal morphology and development of the spinal cord and ganglia of the zebrafish
Authors: Weis Judith Shulman 
Published: April 2021

ABSTRACT
In embryos and young fry of the zebrafish, Brachydanio rerio, the sensory function of the nervous system is fulfilled by a primitive transitory system of Rohon-Beard cells. These are replaced 2 or 3 weeks after hatching by the developing spinal ganglia. The spinal ganglia are typically tear-drop-shaped and occupy a dorsolateral position relative to the spinal cord, with the exception of the first three pairs of ganglia which are large, round, and lie ventrolateral to the cord. As the fish grow, the spinal ganglia grow in size, due to an increase in cell size, and an increase in cell number. This is different from the situation in mammals and chicks, for example, in which the number of cells reached in embryonic stages remains constant, and growth of ganglia is achieved only by means of cell enlargement.
Differentiation ofalkaline phosphatase and glucose-6-phosphatedehydrogenase in rat yolk-sac
Authors: Johnson E. Marshall , Spinuzzi Ralph 
Published: April 2021

ABSTRACT
Electrophoretic and biochemical techniques were applied to homogenates of the visceral yolk-sac of rat embryos at various gestational ages. Alkaline phosphatase was shown by starch gel electrophoresis of normal yolk-sacs to undergo specific sequential changes from day 10 to day 20 of gestation. The isozyme repertory on any given day of gestation was achieved by deletions from, or additions to, that of the previous day. Glucose-6-phosphate dehydrogenase was shown, by polyacrylamide gel electrophoresis of normal yolk-sacs, to achieve early in gestation a qualitatively constant number of enzyme forms. Quantitative changes among the enzyme forms occurred as gestation proceeded. A teratogenic folic acid deficiency resulted in the delayed appearance of some enzyme forms as well as the premature disappearance of others in the two enzyme systems studied. The effects of the treatment were selective in that not all of the enzyme forms of the treated material were affected.
The origin of vertebrate limbs
Authors: Coates Michael I. 
Published: April 2021

ABSTRACT
The earliest tetrapod limbs are polydactylous, morphologically varied and do not conform to an archetypal pattern. These discoveries, combined with the unravelling of limb developmental morphogenetic and regulatory mechanisms, have prompted a re-examination of vertebrate limb evolution. The rich fossil record of vertebrate fins/limbs, although restricted to skeletal tissues, exceeds the morphological diversity of the extant biota, and a systematic approach to limb evolution produces an informative picture of evolutionary change. A composite framework of several phylogenetic hypotheses is presented incorporating living and fossil taxa, including the first report of an acanthodian metapterygium and a new reconstruction of the axial skeleton and caudal fin of Acanthostega gunnari. Although significant nodes in vertebrate phylogeny remain poorly resolved, clear patterns of morphogenetic evolution emerge: median fin origination and elaboration initially precedes that of paired fins; pectoral fins initially precede pelvic fin development; evolving patterns of fin distribution, skeletal tissue diversity and structural complexity become decoupled with increased taxonomic divergence. Transformational sequences apparent from the fish tetrapod transition are reiterated among extant lungfishes, indicating further directions for comparative experimental research. The evolutionary diversification of vertebrate fin and limb patterns challenges a simple linkage between Hox gene conservation, expression and morphology. A phylogenetic framework is necessary in order to distinguish shared from derived characters in experimental model regulatory systems. Hox and related genomic evolution may include convergent patterns underlying functional and morphological diversification. Brachydanio is suggested as an example where tail-driven patterning demands may have converged with the regulation of highly differentiated limbs in tetrapods.
Growth factors in development: the role of TGF-β related polypeptide signalling molecules in embryogenesis
Authors: Hogan Brigid L. M. , Blessing Manfred , Winnier Glenn E. , Suzuki Noboru , Jones C. Michael 
Published: April 2021

ABSTRACT
Embryonic induction, the process by which signals from one cell population influence the fate of another, plays an essential role in the development of all organisms so far studied. In many cases, the signalling molecules belong to large families of highly conserved proteins, originally iden- tified as mammalian growth factors. The largest known family is related to Transforming Growth Factor-β (TGF-β related to Transforming Growth Factor-β and currently consists of at least 24 different members.
Genetic studies in Drosophila on the TGF-β related gene, decapentaplegic (dpp), reveal the existence of conserved mechanisms regulating both the expression of the protein during development and the way in which it interacts with other signalling molecules to generate pattern within embryonic tissues. Comparative studies on another TGF-β related gene, known as Bone Morphogenetic Protein-4 (BMP-4), in Xenopus and mouse point to a conserved role in specifying posteroventral mesoderm during gastrula- tion. Analysis of other polypeptide signalling molecules during gastrulation suggests that their interaction in the generation of the overall body plan has also been conserved during vertebrate evolution.
Les effets de la centrifugation sur la blastula et la jeune gastrula des Amphibiens
Authors: Pasteels J. 
Published: April 2021

ABSTRACT
Nous avons montré dans les deux premiers mémoires de cette série que la centrifugation aux stades blastula et jeune gastrula peut provoquer une activation de redoblaste-, c’est à dire que sans aucune intervention d’un inducteur éventuel, l’ectoblaste constitue des tissus nerveux et neuroïdes, de la chorde, des somites, du pronéphros. Le caractère autonome de cette activité a pu être démontré par des expériences d’explantations (Pasteels, 1953a, p. 15) ou de greffes, soit homoplastiques (Pasteels, 1953a, p. 16), soit hétéroplastiques (Pasteels, 1953a, p. 17).
The Inducing Action of the Bone-marrow of the Guinea-pig after Alcohol and Heat Treatment in Implantation and Explantation Experiments with Embryos of Triturus
Authors: Toivonen Sulo 
Published: April 2021

ABSTRACT
In previous implantation experiments (Toivonen, 1953) the alcohol-treated bone-marrow of the guinea-pig had proved to be a very specific inductor of mesodermal structures. 2.The same material has been treated in addition for 10 minutes in hot water at 80°-90° C. and then used as inductor in implantation experiments with whole gastrulae of Triturus vulgaris. The results of this experiment show that the previous mesodermal activity of the inductor has completely disappeared; it now induces purely epidermal formations, such as lenses, lentoids, and balancers. In explantation experiments with the ‘sandwich’ method the alcohol-treated bone-marrow tissue has induced the same mesodermal structures as in the previous series with whole gastrulae. Heat-treated bone-marrow has induced in the ‘sandwiches’ normal epidermis in the neighbourhood of the inductor, and in addition lentoids and balancerlike formations. Because the previously very strong mesodermal activity of the inductor has disappeared as a result of the heat treatment and the treated inductor has only been able to exert a weak epidermal activity, it is assumed that the heat treatment has inactivated the independent, thermolabile mesodermal agent, and the epidermal agents, which are present in the inductor, have consequently been enabled to exert their own effect. The chemical nature of the mesoderm-inducing agent is discussed; and also the similarity of the tissue-specific agents which presumably regulate regeneration in adult vertebrates and the embryonic inducing agent.
The Relation of the Interrenal Blastema to the Origin of the Somatic Tissues of the Gonad in Frog Tadpoles
Authors: Vannini Enrico , Sabbadin Armando 
Published: April 2021

ABSTRACT
In frog tadpoles the interrenal blastema proliferates from the lateral plates in the zone where the splanchnopleures meet to form the dorsal mesentery. At first the interrenal proliferation appears distinct and separate from the mesonephric blastemata which, in the form of nephrogenic cords, occupy a more lateral site. In later stages the interrenal blastema moves dorsally from its site of origin to join secondarily, under the aorta, the medial faces of the mesonephric blastemata, which are now differentiating their tubular structures. The interrenal blastema in early stages contracts relationships with the primordial germ-cells, when the latter form a median unpaired genital ridge at the mesenteric root; and it provides these cells with the first somatic follicular elements, which will then take part in the genesis of the gonadal cortex. A further participation of the interrenal blastema in the constitution of the gonadal cortex is also observed later, at the stage when paired genital ridges lie one at each side of the dorsal mesentery. In this stage interrenal cells descend towards the gonadal primordia, moving down along the walls of the vena cava, and penetrate between the germ-cells, contributing further to the formation of their follicles. The interrenal blastema later continues to penetrate into the gonadal rudiment, now providing only medullary tissue. Such embryological relationships between the interrenal blastema and the somatic cortical and medullary tissues of the gonads suggest the following points. (a) They appear to be in accord with the chemical and physiological likeness of the steroid hormones which will be secreted by these tissues in the adult. (b) They further suggest that sex differentiation of the Amphibian gonads is not based on a predetermined antagonism between a cortical and a medullary somatic tissue, each different from the beginning both in activity and in embryonic origin. On the contrary, the common embryological derivation of these territories agrees very well with their reported power of partly modulating themselves in either an ovarian or a testicular direction, according to the gonadal sex differentiation. The feminizing potentiality of the cortex on the one hand, and the masculinizing potentiality of the medulla on the other hand, seem thus to establish themselves little by little, during the process of gonad differentiation, under the activity of the genetical factors of sex determination. Analogous powers of transforming their morphogenetic destinies seem also to have already been reported, by other workers, for the cells lying in the boundary zone between the interrenal and the mesonephric blastemata. All the blastemata of the urogenital area, which have a mesodermal origin, seem therefore to be endowed with a certain degree of pluripotentiality, their definitive morphogenetical determination being gradually attained in the course of development.
A quantitative approach to the detection of nuclear activity after differential damage to nucleus and cytoplasm in early development
Authors: Neyfakh A. A. , Rott N. N. 
Published: April 2021

ABSTRACT
For studying nucleo-cytoplasmic relations during development various selective influences on the nucleus and cytoplasm are widely used as the main method of experimental analysis. However, the application of such techniques presents difficulties both in obtaining evidence that shows the specificity of a nuclear or cytoplasmic effect by a chosen agent and in the quantitative evaluation of the extent of damage.
The role of acid phosphatase in the fusion of the secondary palate
Authors: Angelici D. , Pourtois M. 
Published: April 2021

ABSTRACT
Complete closure of the secondary palate must progress through two con-secutive events: the converging movement of the palatal shelves and their subsequent fusion at the line of contact. Each step is indispensable in normal palatal development since, theoretically, a palatal cleft might be the consequence of a failure of either.
Changes in the rate of cell divisions in the course of early development of diploid and haploid loach embryos
Authors: Rott N. N. , Sheveleva G. A. 
Published: April 2021

ABSTRACT
The period of development preceding gastrulation can be divided into two stages. The first is characterized by rapid synchronous cell division. True interphase, which is characterized by the fusion of karyomers and the occurrence of a nucleolus, is absent at this stage. During the second stage the rate of cell division decreases and divisions are asynchronous.
La colonisation des ébauches gonadiques par les cellules germinales de l’embryon de Poulet, en culture in vitro
Authors: Dubois Regis 
Published: April 2021

ABSTRACT
Chez les Vertébrés, la ségrégation de la lignée germinale s’effectue dès les stades les plus précoces du développement. Les cellules germinales primordiales (CGP) apparaissent toujours hors des gonades et se trouvent souvent localisées dans des territoires bien délimités, plus ou moins éloignés des ébauches gonadiques présomptives. La destinée des gonocytes étant liée de façon irréductible à leur installation dans les ébauches génitales, ces cellules entreprennent, à chaque génération, une migration qui les conduit infailliblement aux épithéliums germinatifs.
The effect of rubella and herpesvirus hominis on the pre- and post-implantation stages of pregnancy in laboratory animals
Authors: Oxford J. S. , Sutton R. N. P. 
Published: April 2021

ABSTRACT
The teratogenic effect of rubella virus in humans has now been well documented (Ingalls, Plotkin, Meyer & Parkman, 1967) and virus isolation studies have suggested that rubella virus causes embryopathy by actually infecting the cells of the developing foetus (Alford, Neva & Weller, 1964). However, a laboratory animal model is required for controlled studies of the teratogenic activity of rubella virus and for the assessment of possible preventative measures. Such an animal system would also be useful for screening attenuated rubella vaccine strains for teratogenic properties. Pregnant primates have been used in preliminary experiments with rubella virus (Parkman, Phillips & Meyer, 1965) but suffer from the disadvantages of size, expense and difficulty of mating. Both the hamster (Ferm&Kilham, 1965) and the rabbit (Gibson, Staples & Newberne, 1966) have proved useful animals for the investigation of teratogenic agents. We have described previously the adaptation of strains of rubella virus to small laboratory animals (Oxford & Schild, 1966; Oxford, 1967) and wish now to report studies of the infection of rabbits and hamsters with rubella virus in the early stages of pregnancy.
Immunoelectrophoresis of egg and plasma proteins during development of the house sparrow, Passer domesticus
Authors: Bush Francis M. , Seibert Charlene A. 
Published: April 2021

ABSTRACT
Differentiation of plasma proteins in avian embryology has been analysed by electrophoresis (Brandt, Clegg & Andrews, 1951; Schechtman, 1952; Heim & Schechtman, 1954; Weller & Schechtman, 1962). Information has been obtained on affinities between plasma and egg proteins by electrophoretic studies (Wise, Ketterer & Hansen, 1964) and by immunochemical studies (Kaminski & Durieux, 1956; Williams, 1962a; Stratil, 1967; Zaccheo & Grossi, 1967).
Endocrine influences on growth and pigmentation of embryonic down feather cells
Authors: Johnson Leland G. 
Published: April 2021

ABSTRACT
Rawles (1960) and Hamilton (1952) have outlined the development of the down feather. Details of the development and interaction of the epidermal constituents and melanocytes of the down feather were reported by Watterson (1942) and Goff (1949) described the development of the mesodermal portions of the feather.
Ultrastructure et cytochimie ultrastructurale de la vésicule germinative et du cytoplasme périnucléaire de l’oocyte mûr de Xenopus laevis
Authors: Gansen Par P. Van , Schram A. 
Published: April 2021

ABSTRACT
Les oocytes et les œufs de Batraciens constituent, depuis longtemps, un material de choix pour les embryologistes. Au cours de ces dernières années, les phénomènes initiaux du développement embryonnaire ont été étudiés avec toute la précision que permettent les techniques biochimiques et cytochimiques actuelles. En particulier, l’étude de la maturation des oocytes de Batraciens a été reprise par plusieurs auteurs depuis que ce phénomène peut être obtenu in vitro (Dettlaff, Nikitina & Stroeva, 1964; Dettlaff, 1966; Brachet, 1965a, b, 1967; Smith, Ecker &. Subtelny, 1966). Brachet a mis en évidence l’apparition, au cours de la maturation, de grains Feulgen-positifs distincts des chromosomes, dans le suc nucléaire de Rana, de Xenopus et de Bufo ainsi que dans le cytoplasme périnucléaire des oocytes de Bufo. Ces grains se rassemblent dans le cytoplasme cortical, puis ils disparaissent (Brachet, 1965a).
Extra-uterine development of mouse blastocysts cultured in vitro from early cleavage stages
Authors: Billington W. D. , Graham C. F. , McLaren Anne 
Published: April 2021

ABSTRACT
Many experiments indicate that oviducal mouse eggs are unable to form embryonic tissues following transplantation to extra-uterine sites; they give rise only to trophoblast and extra-embryonic membranes (Fawcett, Wislocki & Waldo, 1947; Fawcett, 1950; Chester-Jones, 1951; Whitten, 1958; Kirby, 1962; Billington, 1965). Possible rare exceptions exist in the reports by Runner (1947) and Stevens (1967). In contrast, about a quarter of uterine blastocysts form mor-phologically normal embryos when similarly transplanted (Kirby, 1963; Billington, 1965). The conditions under which the mouse eggs reach the blastocyst stage may also have developmental consequences. Eggs cultured in vitro to the blastocyst stage (Whitten, 1956) or tube-locked blastocysts (Kirby, 1962) did not develop embryonic tissue in extra-uterine sites, but were capable of complete development following transfer to a receptive uterus.