bluuebunny/crossref_metadata_2025_split huggingface dataset:
The influence of ‘hypophysectomy’ on bone growth and alkaline phosphatase activity in the chick embryo
Authors: Mcwhinnie D. J. , C. Thommes Robert 
Published: April 2021

ABSTRACT
Wet weights, total bone alkaline phosphatase activity and specific alkaline phosphatase activity were determined on demarrowed femurs of normal, ‘hypophysectomized’ and pituitary-grafted chick embryos at selected intervals of incubation. In normal bones, all parameters noted above increased progressively through developmental time. ‘Hypophysectomy’ by means of surgical decapitation significantly retarded the normal increase of femur wet weight, total and specific alkaline phosphatase activity; in embryos bearing pituitary transplants, there was a return towards normal values. The possible role(s) of the pituitary in skeletal maturation and enzyme synthesis or activation is discussed.
Abnormal development of pre-implantation mouse embryos grown in vitro with [3H]thymidine
Authors: Snow M. H. L. 
Published: April 2021

ABSTRACT
Mouse embryos were grown in vitro from the 2-cell stage to blastocysts in the presence of [3H]thymidine. Methyl-T-thymidine and thymidine-ó-T(n) were used and both forms found to be lethal at concentrations above 0 · 1 μ Ci/ml. Both forms of [3H]Tdr at concentrations between 0 · 01 and 0 · 1 μ Ci/ml caused a highly significant (P &lt; 0·001) reduction in blastocyst cell number. The reduction in cell number, which was positively correlated with specific activity and tritium concentration, was associated with cell damage typical of radiation damage caused by tritium disintegration. Thymidine-6-T(n) also significantly reduced the number of 2-cell embryos forming blastocysts whereas methyl-T-Tdr did not. This difference in effect is assumed to be caused by contamination of one form of [3H]Tdr with a by-product of the tritiation process.
A study of the cleavage stages showed that almost all the reduction in cell numbers could be accounted for by selective cell death occurring at the 16-cell stage. Cells which survive that stage cleave at a normal rate. The cells that are most susceptible to [3H]Tdr damage were found to normally contribute to the inner cell mass. The [3H]Tdr-resistant cells form the trophoblast. It is possible to grow blastocysts in [3H]Tdr such that they contain no inner cell mass but are composed entirely of trophoblast. Comparatively short (12 h) incubation with [3H]Tdr at any stage prior to the 16-cell stage will cause this damage. Possible reasons for this differential effect are discussed, and also compared with damage caused by X-irradiation.
The effect of X-radiation on spermatogenesis and the fertility of Schistocerca gregaria (Forsk.)
Authors: Coggins Peter B. 
Published: April 2021

ABSTRACT
Normal spermatogenesis and the effects of X-radiation on the male locust germ cells have been studied with the aid of light and electron microscopy. Adult insects were irradiated with doses of 100–500 rad (i.e. 1–5 J kg−1) and subsequently examined, at intervals, up to 55 days later. In secondary spermatogonia all doses caused nuclear fragmentation and necrosis, and in primary spermatogonia and a few spermatocytes caused a delay in division. Spermatids and the majority of spermatocytes developed into spermatozoa which were passed from the follicles to the seminal vesicles. The supply of sperm was, subsequently, temporarily stopped. The follicles were eventually repopulated by the division of the primary spermatogonia. Radiation-induced abnormalities, e.g. the formation of supernumerary centrioles, flagella and definitive mitochondria, were most common in the cytoplasm. The Golgi bodies and acrosome seemed to be unaffected. Abnormal outgrowths of the late spermatid and sperm nuclei appeared to be caused by the presence of the numerous centrioles and flagella. The bright yellow coloration of the cuticle, which is characteristic of sexually mature males, was not fully developed in irradiated males. Breeding experiments showed a significant reduction, when compared to the controls, in the number and percentage hatchability of eggs obtained from females mated to irradiated males. The doses of radiation employed did not appear to affect the longevity of the adults.
The migration of neural crest cells to the wall of the digestive tract in avian embryo
Authors: Douarin Nicole M. Le , Teillet Marie-Aimée 
Published: April 2021

ABSTRACT
Isotopic and isochronic grafts of quail neural primordium in chick embryos have been made. Due to the particular structure of their nuclei, quail cells can be distinguished from chick cells and so be used as natural markers to study the migration of neural crest cells. We have been able to demonstrate by this technique that the parasympathetic enteric ganglion cells arise from two different levels of the embryonic neural axis which correspond to the vagal and lumbo-sacral parasympathetic centres. The main source of the enteric neuroblasts is located at the level of the somites 1 – 7. It gives rise to ganglion cells which migrate in the whole gut including the large intestine and rectum. The other region from which enteric neuroblasts originate is situated behind the level of the 28th somite and gives rise only to some post-umbilical gut ganglion cells. In this region of the intestine the ganglia are made up of a mixture of cells arising from the vagal and the lumbo-sacral levels of the neural axis. The part of the neural primordium between the 8th and the 28th somite does not participate in the formation of the enteric ganglia. The chronology of the enteric neuroblast migration has been studied. Most cells of vagal origin leave the neural crest before the 13-somite stage but the migration lasts sometimes until after the 16-somite stage. Those cells which have to reach the hind-gut level accomplish a long-term migration which can be evaluated at 6 days or more. The presumptive neuroblasts of lumbo-sacral origin are not found in the hind-gut before the 7th day of incubation. In our experiments we have never observed the migration of any quail cells into the endoderm of the chick host embryo. Therefore we consider that enterochromaffin cells of the digestive epithelium are not derived from the levels of the neural crest concerned in these experiments (i.e. rhombencephalic and medullary Anlagen).
In vitrostudies of the influence of hormones on tail regeneration in adultDiemictylus viridescens
Authors: Vethamany-Globus Swani , Liversage Richard A. 
Published: April 2021

A total of 260 tail blastemata (13 to 15-day regenerates) of adult newts was cultured, with 170 controls, in medium no. 1760 (modified Parker’s Medium, CMRL-1415) for 98 h at 20 ±0·5 °C. Various hormones, related to the regeneration process, were added individually and in combinations. If hormones were not included in the culture medium, blastema growth and differentiation did not ensue. The results of these in vitro experiments further showed that the presence of insulin was essential in the maintenance and promotion of growth and differentiation of the explanted blastemata. In addition, thyroxine also promoted a limited amount of growth and differentiation of the blastema and maintained a normal epidermis in culture. Furthermore, advanced cartilage differentiation and maximum growth of the blaste-mata were observed in cultures treated with combinations of insulin, growth hormone and hydrocortisone; insulin, growth hormone and thyroxine or all four of these hormones. The evidence presented indicates that the collective influence of the hormones (insulin, growth hormone, hydrocortisone and thyroxine) is greater than the effect of any of them individually.The action of insulin on the tissues and the metabolism of vertebrates is discussed and related to the regeneration process. The possible involvement of a multiple hormone action (insulin, thyroxine, hydrocortisone and growth hormone) in regeneration is discussed.
Measurements of cell adhesion I. Quantitative studies of adhesion of embryonic chick cells
Authors: Hornby Janet E. 
Published: April 2021

ABSTRACTCell suspensions were prepared from the kidney, liver and heart of chick embryos of 5 or 8 days of incubation, and from the limb-buds of chick embryos of 5, 6, 7, 8 or 9 days of incubation. When these suspensions were aggregated under laminar shear in a Couette viscometer or random motion in a reciprocating shaker they obeyed the theoretical relationships derived for flocculating lyophobic sols. The values of the collision efficiency found for the different cell types under given conditions were used to calculate the force of interaction between cells of each type. The force of interaction ranged between 9 ×10−11 N (8-day heart) and 3 ×10−9 N (8-day liver). The forces of interaction between cells appear to be responsible for aligning the membranes of adjacent cells with a 10–20 nm gap. It is possible to arrange the cell types in a hierarchy based on the forces of interaction between them. The possible role of these forces in cell specificity is considered.
The appearance of muscle protein and myofibrils within the embryonic chick limb-bud
Authors: Thorogood P. V. 
Published: April 2021

ABSTRACT
Myotubes are present in the developing hind limb of the embryonic chick at 5 days. An immunofluorescence technique was used to detect actomyosin within the myotubes. The earliest detectable appearance of this muscle protein was at six days of development, at sites located peripherally beneath the flattened dorsal and ventral surface of the limb. These dorsal and ventral loci are interpreted as representing the primordial extensor and flexor muscles. At the ultrastructural level the cytoplasm of the myotubes contains fibrillar components which are apparently aggregating to form myofibrils. A rudimentary banding pattern can be distinguished.
Évolution enzymatique destissus foetaux et placentaires de Rat en carence tératogène de riboflavine
Authors: Courcy G. Potier de , Desmettre-Miguet S. , Macquart-Moulin M. R. , Terroine T. 
Published: April 2021

ABSTRACT

Enzymic changes of foetal and placental tissues of the rat in teratogenic riboflavin deficiency
The electrophoretic pattern of alkaline phosphatase was studied in teratogenic riboflavin deficiency in the whole foetus, chorioallantoic placenta and visceral yolk-sac of the rat in order to follow the course of their differentiation from day 13 to day 20 of gestation. Lactic-dehydrogenase (LDH) isozymes were chosen in the case of foetal organs (heart, intestine and kidneys) as a more sensitive test. A fluorometric analysis of alkaline phosphatase was also performed to evaluate more precisely quantitative modifications brought on by maternal riboflavin deficiency in the placenta and the whole foetus.
The importance of alkaline phosphatase in rat yolk-sac was indicated in the last period of gestation by the presence of a specific rapid isozyme band from the 16th to the 21st day, simultaneously with a greater complexity of the electrophoretic picture of this membrane. Placenta and foetus, on the other hand, were shown to possess two common bands but those concerned with the foetus appeared later and were related to the onset and increase of ossification. In the foetal organs, differentiation of LDH isozymes appeared specific for each organ studied; while the heart tissue showed five bands on the 16th day, kidney arrived at this stage only on the 21st day, indicating a slower maturation of this tissue.
At the end of gestation riboflavin deficiency delayed the appearance of rapid isoenzymes of alkaline phosphatase in the whole foetus and of LDH in the foetal kidneys, suggesting a similar delay in the course of metabolic differentiation of the skeleton and kidney tissues. Deficiency had no effect upon placental isoenzyme development but in this organ it greatly reduced the biochemical alkaline phosphatase activity, especially on day 13. This result suggests the participation of the enzyme in the general hypotrophy of the foetus by a decrease in nutrients carried by the placenta. On the other hand, the decline in the alkaline phosphatase activity of the whole foetus is related to the delayed appearance of mineralization.
Binucleate and polyploid cells in the decidua of the mouse
Authors: Ansell J. D. , Barlow P. W. , Mclaren Anne 
Published: April 2021

ABSTRACT
The development of the decidua in rodents is associated with the production of multinucleate and giant cells (Fig. 1A). In the rat, binucleate cells appear throughout the secondary or antimesometrial zone of the decidua by the eighth day of pregnancy (Krehbiel, 1937), while in the mouse this region is characterized by large bi-, tri-, or tetranucleate cells (Snell & Stevens, 1966). All decidual cells may eventually enlarge, containing nuclei of a size consistent with a DNA content of four, eight and possibly even higher multiples of the haploid complement (Sachs & Shelesnyak, 1955). In the white rat spectrophotometric determination of DNA levels in decidual cells indicates that by the tenth day of gestation ploidy levels have reached 16C–32C, with maximal levels of 64 times the haploid DNA content (Zybina & Grishchenko, 1972). The mechanism of nuclear enlargement in decidual tissue is as yet unknown.
Development in vitro of mouse embryos from the two-cell egg stage to the early somite stage
Authors: Hsu Yu-Chih , Baskar John , Stevens Leroy C. , Rash John E. 
Published: April 2021

ABSTRACT
About 1 –3% of mouse blastocysts, which had initially been cultured from the two-cell stage in chemically defined medium or about 3 –5% of blastocysts which were explanted from the uterus, developed to the early somite stage when cultured in vitro on collagen. Two cell eggs were initially cultivated in chemically defined medium to the blastocyst stage. Blastocysts were then transferred to Eagle’s minimal essential medium (MEM) plus 10% heat-inactivated calf serum. Two barriers to further development were overcome. First, the formation of endoderm and ectoderm from the inner cell mass immediately after attachment to collagen. Second, formation of the embryo proper from the embryonic region. Both barriers were overcome by using heat-inactivated human cord serum after the blastocysts hatched from the zona pellucida and attached to collagen. After attachment, embryos were cultured in MEM plus 20% heat-inactivated human cord serum which was changed daily until early somite stages. Apparently normal healthy development in vitro occurred, as judged by light and electron microscopic examination.
Germ cell migration in toad (Bufo bufo): effect of ventral grafting of embryonic dorsal regions
Authors: Giorgi Piero P. 
Published: April 2021

ABSTRACT
Bufo bufo embryos were used at the tail-bud stage for the grafting of two different dorsal regions (cephalic and caudal tracts) into the ventral side of the embryo (cf. Fig. 1). Germ cell localization was studied at the beginning of larval life. The results seem to confirm the original finding of Gipouloux (1970) who suggested that in anurans germ cells migrate under the attraction of a substance produced by the dorsal mesodermal tissues.
The attractive action of dorsal tissue was confined to the caudal region of the embryo. In operated specimens the migration of germ cells was drastically altered. The genital ridges of host embryos were almost sterile, while numerous germ cells appeared associated with caudal grafts. A considerably smaller number of germ cells was associated with cephalic grafts.
About 80% of germ cells associated with caudal grafts were present at the same levels where a well-developed dorsal mesentery was also present. It is suggested that the formation of the dorsal mesentery plays a morphogenetic role in segregating primordial germ cells from other endodermal cells and contributes to their final localization in the genital ridges.
Ultrastructural features of ectodermal—mesenchymal relationships in the developing limb of Xenopus laevis
Authors: Tarin D. , Sturdee A. P. 
Published: April 2021

ABSTRACT
Electron microscopical study of the formation of the hind limb of the toad Xenopus laevis between stages 49 and 53 of larval development has been performed with special reference to the relationships between the apical ectodermal ridge and the underlying mesenchyme. It has been found that the intervening collagenous layer is thinner in the vicinity of the ridge than elsewhere and that the subjacent mesenchymal cells are more loosely arranged. There are also fewer mesenchymal filopodia crossing the collagenous layer than proximally although the distribution of delicate vertically disposed threads, also observed at the ecto-mesenchymal junction, is uniform over the entire bud. Overall, it is concluded that the fine structural features of Xenopus limb development, during these stages, do not give clear insight into the mechanisms by which the apical region exerts its morphogenetic effects.
Normal incorporation rates for precursors of collagen and mucopolysaccharide during expression of micromelia induced by 6 -aminonico tinamide
Authors: Seegmiller Robert E. , Runner Meredith N. 
Published: April 2021

ABSTRACT
Further delineation of mechanisms by which 6-aminonicotinamide (6-AN) induces micro-melia in the chick embryo was investigated by studies on rates of incorporation of thymidine, proline, glucosamine and sulfate as precursors to DNA, collagen and mucopolysaccharide, respectively. Twentyfour hours after in ovo administration of the vitamin antagonist, 6-AN, to day-4 chick embryos, hind limbs from experimental and control groups were excised and incubated for 1 h in medium containing 3 × 10 − 6 M radioactive precursor. Molar incorporation of precursors into the TCA-precipitable fraction showed, in isolated limb buds, (a) that 6-AN enhanced incorporation of thymidine, (b) that 6-AN inhibited utilization of sulfate, and (c) that 6-AN did not significantly alter utilization of glucosamine and proline.
Rates of incorporation of thymidine, glucosamine and proline indicate that 6-AN is not cytotoxic to the isolated limb bud. Enhanced incorporation of thymidine suggests expression of compensatory change 24 h after initial effects of 6-AN on DNA synthesis. Rate of in-corporation of proline suggests that, under the influence of 6-AN, tropocollagen was syn-thesized in normal quantities by limb cells. Similarly, rate of incorporation of glucosamine suggests that under the influence of 6-AN normal amounts of hexosamine sugars were being attached to the nascent core-protein of chondroitin. Inhibition of sulfation and failure to complete the chondroitin sulfate molecule seem to account for 6-AN-induced micromelia. This suggests that sulfation depends upon specific NAD-dependent dehydrogenase reactions. As far as can be established by rates of incorporation of labeled precursors, 5-day limb buds, at 24 h after exposure to teratogenic levels of 6-AN, synthesize matrix proteins and hexo-samine polysaccharides at normal rates.
The in vivo behaviour of achondroplastic cartilage from the cartilage anomaly (can/can) mouse
Authors: Johnson D. R. 
Published: April 2021

ABSTRACT
Explanted cartilage from can/can mice aged 3 days shows increased protein and mucopoly-saccharide synthesis. Injection of [U-14C]glucose into 3-day-old can/can mice failed to duplicate the increased mucopolysaccharide formation. Transplanted can/can tail vertebrae grown in the renal capsule of normal sibs grew less well than those from normal litter-mates’ also suggest-ing that the increased metabolism seen in vitro is not a feature of in vivo development.
Biochemical observations on the cartilage of achondroplastic (can) mice
Authors: Johnson D. R. , Hunt D. M. 
Published: April 2021

ABSTRACT
The achondroplastic can/can embryo can be distinguished from normal litter-mates at 17 days by reduced protein synthesis. After 3 days post partum protein synthesis is increased to levels well above normal, as is incorporation of glucose into mucopolysaccharides and the levels of uridine diphosphoglucose dehydrogenase and UDP-glucose-4-epimerase.
Experimentally induced aberrations in the pattern of differentiation in the cellular slime mouldDictyostelium discoideum
Authors: Farnsworth Paul 
Published: April 2021

ABSTRACTThis paper describes a set of perturbatory experiments designed to elucidate aspects of the mechanism by which the normal pattern of differentiation is specified.Experiments are described which investigate the alterations in development seen in aqueous environments, with changes in humidity and with the introduction of permeable and imperme-able barriers.The following results are reported: The pattern of differentiation and the various morphologies of fruiting bodies formed when cell masses are placed in or on drops of buffer.The alteration of the ratio of cell types formed in aqueous environments in the presence of urethane mercaptoethanol or EDTA.Humidity dependent changes in polarity and the increase of the number of develop-mental axes with humidity.The formation of two developmental axes in cell masses bisected by impermeable barriers and a special case of bisection which induces the whole cell mass to form spores.The induction of all of any of a cell mass enclosed in a ‘cellulose’ tube to form a tissue ultrastructurally demonstrable to be the same as that of stalk.These results are discussed in relationship to the work of other authors and the problem of the specification of the patterns of differentiation in the slime moulds. The results are pre-sented in support of a model proposed previously by the author in which the pattern of the two differentiated cell types is inherent in the morphogenetic changes of culmination, and essential requirements of such a model are correlated with these observations.
Rôle des cellules mésectodermiques issues des crêtes neurales céphaliques dans laformation des arcs branchiaux et du squelette viscéral
Authors: Lievre C. Le 
Published: April 2021

ABSTRACT
The participation of neural crest cells in the formation of the branchial arches and especially of the hypobranchial skeleton has been studied with heterospecific grafts of quail neural tube into the chick embryo. According to the labelling technique devised by Le Douarin, the differences between quail and chick interphase nuclei make it possible to use quail cells as cellular markers in this system.
The excision of the mesencephalo-rhombencephalic primordium of 4-to 12-somite chick embryos results in the atrophy of the branchial arches, and in important deficiencies of the hypobranchial skeleton. Nevertheless, the nearly complete absence of the branchial mesen-chyme does not prevent the visceral pouches and clefts from forming.
The isotopic and isochronic graft of quail neural primordium into the chick shows that the mesenchymal component of the branchial arches is of neurectodermal origin, except for the muscle plates and the endothelium of the aortic arches, which derive from the mesoderm. The mesencephalic neural crests give rise to the totality of the mesenchyme of the first branchial arch and partially to that of the second one, while the rhombencephalon con-tributes to the formation of the second, third and fourth arches.
The stability of the marker system produced by quail cells implanted into the chick makes it possible to follow the migrating cells until they have reached their definitive localization in the various structures of the hypobranchial skeleton, which thus appears to be entirely of neurecto-dermal origin. The cells arising from the mesencephalic neural primordium constitute the lower jaw skeleton (Meckel’s cartilage and bones) and are all still in the process of migration at the 6-somite stage. Cells originating from the rhombencephalon have left the neural axis at the 9-to 10-somite stage for the anterior part (in front of the first somite) and at the 11-to 12-somite stage for the posterior rhombencephalon.
Differentiation of mesectodermal cells into chondrocytes and osteocytes has been observed during the morphogenesis of the visceral skeleton.