bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tissue-specific mitotic inhibition in the kidneys of embryonic grafts and partially nephrectomized host Xenopus laevis
Authors: Chopra D. P. , Simnett J. D. 
Published: April 2021

Immature Xenopus laevis were unilaterally nephrectomized and implanted subcutaneously with stage 38 (prefeeding) larvae.
Rat kidney extract was injected 8 and 16 days after the operation and the mitotic incidence (MI) in the host and implant tissues was measured by the colcemid metaphase arrest technique.
The MI in the kidney of nephrectomized hosts was higher than normal at 8 days but had returned to the control level at 16 days. Injection of kidney extract inhibited mitosis in the host kidney both at 8 and 16 days after partial nephrectomy.
The MI of implant pronephros was higher in nephrectomized than in control hosts both at 8 and 16 days. Injection of kidney extract into nephrectomized hosts inhibited mitosis in the implant pronephros both at 8 and 16 days.
Neither host nephrectomy nor injection of kidney extract had any effect on the MI in the epidermis of the implants.
Unoperated immature Xenopus were injected with rat kidney or liver extracts. Kidney extract inhibited mitosis in the kidney but not in the liver, while liver extract inhibited mitosis in the liver but not in the kidney.
The rate of mitosis in the kidney and liver of normal animals may be controlled by tissuespecific inhibitors of cell division.
Abnormal spermiogenesis in two pink-eyed sterile mutants in the mouse
Authors: Hunt D. M. , Johnson D. R. 
Published: April 2021

ABSTRACT
Abnormal spermiogenesis is described in two neutron-irradiation induced alleles at the pink-eye locus in the mouse. Testicular hypotrophy and abnormal spermateliosis are present, resulting in the formation of giant sperm with abnormal heads and multiple tails. Abnormal sperm-head shape results from abnormal proacrosome formation and multiplication of tail number from a failure in cytokinesis.
The pleiotropic effects of the locus on coat colour, fertility, behaviour and growth are reviewed in conjunction with similar mutants in other rodents: it is suggested that pituitary dysfunction could explain all aspects of the ‘pink-eye’ syndrome.
Laser irradiation of the chick embryo germinal crescent
Authors: Mims Martha Fearon , Mckinnell Robert Gilmore 
Published: April 2021

ABSTRACT
The germinal crescent of head-fold and one-somite-stage chicken embryos was irradiated with multiple pulses of a microbeam ruby laser. Primordial germ cells were not detected in the gonad primordium of six laser-irradiated 5-day embryos; ten laser-irradiated embryos had varying numbers of primordial germ cells. Ten control embryos had gonad primordia populated with many primordial germ cells.
The relationship between cleavage and blastocoel formation in Xenopus laevis
Authors: Kalt Marvin R. 
Published: April 2021

ABSTRACT
Blastocoel formation in Xenopus laevis was investigated by light microscopy using serial sections of epoxy-embedded, staged embryos. The earliest manifestation of the blastocoel in the embryo appeared during the first cleavage as a modification in the animal pole furrow tip. This modification consisted of an expansion of a localized area of the furrow. As the blastocoel became a distinct entity, it remained stationary, while the furrow tip continued to advance inwardly. In contrast, no such furrow cavity was observed in the vegetal pole furrow during its formation. During subsequent cleavages, up to the late morula stage, furrows on opposite sides of any given blastomere had different morphologies. As further divisions occurred, the mode of furrow formation became identical regardless of location in the embryo. It is suggested that the cytokinetic pattern in early amphibian embryos is modified to allow for the formation of the blastocoel. After the blastocoel has formed, the cytokinetic pattern changes to one which is concerned solely with cell division.
A three-dimensional collagen network for cartilage reconstruction
Authors: Moskalewski S. , Kamiński M. , Dukwicz A. 
Published: April 2021

ABSTRACT
To obtain a three-dimensional network which would support cells during culture, cold collagen solution was mixed with cells and converted into a gel at 37 °C. Gelation of collagen did not influence cell viability.
The development of chondrocyte cultures in collagen gels depended on the distance between the cells. Single chondrocytes were surrounded by a mucopolysaccharide ring. The collagen fibres in parts of the cultures with moderate cell density were strongly alcian-blue-positive. Chondrocytes in crowded areas of cultures formed a cartilage matrix. Collagen gel with Ehrlich ascites tumour cells and liver cells remained unchanged after cultivation. Cultures of kidney cells and some chondrocyte cultures shrivelled, owing to partial collagen digestion.
The delicate primary collagen network in some cultures partially transformed to much thicker, long fibres or to distinct capsules around chondrocytes.
Development of division asynchrony and bilateral symmetry in the first quartet of micromeres in eggs of Lymnaea
Authors: Biggelaar J. A. M. van den 
Published: April 2021

ABSTRACT
Experiments were undertaken to investigate the cleavage pattern of eggs of Lymnaea developing into exogastrulae after a treatment for 2 h with 5 × 10−2 M-LiCl at 6 °C at the beginning of second cleavage. It appeared that the 16-cell stage is reached normally, but that in the vegetative cells the following division is considerably retarded. It is assumed that this delay is associated with the suppression of division asynchrony in the first quartet of micromeres, which normally adumbrates bilateral symmetry in the animal hemisphere, and with suppression of gastrulation.
Activités cholinestérasiques dans le foie de Poulet Rôle de l’endoderme dans l’apparition d’activités cholinestérasiques dans la composante mésenchymateuse du tissu hépatique
Authors: Houssaint Par Elisabeth , Douarin Nicole Le 
Published: April 2021

ABSTRACT
Cholinesterases in the chick liver. The role of the endoderm in the appearance of the activity of cholinesterases in the hepatic mesenchyme
The histochemical method of Koelle & Friedenwald (1949), as modified by Gerebtzoff (1953), has been used to investigate the distribution of cholinesterases in the chick embryonic and adult liver. Non-specific cholinesterases and, in a lower proportion acetylcholinesterase, have been detected in the endothelial cells of blood sinusoids of both adult and embryonic hepatic tissue. The hepatocytes do not show any cholinesterase activity.
Cholinesterases appear precociously in the liver mesenchyme, since they already occur in the septum transversum of the 3-day-old chick embryo.
An experimental procedure preventing the invasion of the hepatic mesenchymal Anlage by the endodermic cords has been used. The experimentally isolated hepatic mesenchyme shows an important cholinesterase activity; therefore this activity does not depend on the presence of the hepatocytes.
The grafting of the determined hepatic endodern in the somatopleura of the 3-day-old chick embryo results in the development of hepatic tissue in the body wall. In this experimentally produced liver, cholinesterase activities are present in the endothelial cells which have arisen from somatopleura mesenchymal cells, though normally somatopleural mesenchyme does not possess these enzymes. The role of the endoderm in the appearance of this enzymic activity in the somatopleural mesenchyme is discussed.
Studies on nucleocytoplasmic interactions during early amphibian development
Authors: Brachet J. , Hubert E. 
Published: April 2021

ABSTRACT
The dorsal or the ventral cortex of Xenopus laevis eggs, at the one- or two-cell stage, has been slightly injured with a microneedle; 184 of these eggs have been examined cytologically.
The frequency of early (cleavage) and late (gastrulation, neurulation) abnormalities after dorsal injury was about twice that after ventral injury.
Abnormalities of the mitotic apparatus and of the chromosomes are very frequent during cleavage after slight cortical damage.
At later stages, the previously wounded embryos often display aneuploidy, as shown by cytophotometric measurements of the DNA content of the individual nuclei. Aneuploidy is much more frequent after injury of the dorsal cortex than injury of the ventral cortex.
Autoradiography studies have shown that there is a close correlation between morphogenesis and nuclear RNA synthesis.
The results are discussed in relation to current ideas on the morphogenetic and genetic significance of the grey crescent and its cortex.
Hydrocortisone-increased glycogen deposition and its dependence on tissue interactions in mouse embryonic lung developing in vitro
Authors: Alescio T. , Dani A. M. 
Published: April 2021

ABSTRACT
We have performed experiments showing that the epithelial tree of embryonic rudiments, when cultured in vitro in the presence of hydrocortisone, sharply increases its glycogen content. The distribution of the polysaccharide remains very similar to that observed in the absence of the hormone.
The increased glycogen deposition in response to the hormonal treatment requires the presence of homologous (bronchial) mesenchyme, as shown by the complete inability of the epithelium to accumulate glycogen when experimentally associated with metanephrogenic mesenchyme.
The increased deposition of glycogen in the epithelial tree does not result in an enhanced rate of budding activity.
RNA synthesis at the two-cell stage of mouse development
Authors: Knowland John , Graham Chris 
Published: April 2021

ABSTRACT
This paper describes a method for quantitative extraction of nucleic acids from cultured pre-implantation mouse embryos in a form suitable for electrophoresis, and its application to the analysis of RNA synthesized during early mouse development. The nucleic acids synthesized by early mouse embryos have been identified by the use of RNase, DNase and mild alkaline hydrolysis. No obvious differences in the kinds of RNA synthesized in the blastocyst, trophoblast or embryonic fibroblast were found. At the two-cell stage of mouse development, which is the earliest that can be successfully labelled with radioactive precursors of RNA, all major RNA classes with similar electrophoretic mobilities to the RNA species of adult cells are synthesized, and it is likely that 28 s and 18 s RNA are synthesized at this stage. It is suggested that the onset of rRNA synthesis may not be associated with a particular stage of embryonic development.
Cell lines derived from late embryonic stages of Drosophila melanogaster
Authors: Schneider Imogene 
Published: April 2021

ABSTRACT
The development of three cell lines initiated from the late embryonic stages of Drosophila melanogaster is described. The primary cultures consisted of trypsinized fragments from embryos 20–24 h old. The length of time between primary culture and subsequent subculture varied from 8 months for the first line to 3 weeks for the third. All three lines have been maintained in vitro for more than a year. The characteristics of each line are given and evidence is presented that at least one line is derived from imaginal disc cells. A few comments on insect tissue culture in general are also made.
Regeneration, post-embryonic induction and cellular interaction in the eye of Periplaneta americana
Authors: Hyde Cornelia Anne Tuten 
Published: April 2021

ABSTRACT
The eye grows by the addition of new ommatidia rather than by an increase in size of existing ones. New ommatidia develop as a result of induction of epidermal cells by functional ommatidia. The eye has great regenerative ability, but following removal of the entire eye and the growth zone that surround it regeneration does not occur. Transplanted eye cells or epidermal cells from normal-eyed or from lavender-eyed mutants resulted in the development of normal eye pigmentation in a mutant that lacked any pigmentation in the eye. Only the eye to which the graft had been made developed pigments. The development of pigments was a result of tissue contact, not of a blood-borne factor. When epidermal tissues from the prothorax of normal-eyed roaches were placed above the developing eye of a mutant with no pigment in the eye they were eventually incorporated into the eye as it grew. When these cells became eye cells, normal eye pigments were synthesized. Growth of the eye is by a constant recruitment of epidermal cells that express their own genetic capability when they become eye cells.
DNA synthesis in the preimplantation mouse embryo
Authors: Barlow P. , Owen D. A. J. , Graham Chris 
Published: April 2021

ABSTRACT
Strain PO preimplantation embryos were labelled with [3H]thymidine. The incorporation of the label was studied by autoradiography of air-dried and serially sectioned embryos. DNA amounts were measured with a microdensitometer.
The following observations were made at the 5- to 16-cell stages. All nuclei contained 2C–4C amounts of DNA and all could eventually synthesize DNA. However, after short labelling intervals, unlabelled nuclei were found with 2C and 4C amounts of DNA. We concluded that both the Gx and the G2 phases of the cell cycle were present at this time. Embryos were found in which the S phase of the 4th and the 5th cell cycles post fertilization overlapped. In 12- to 15-cell embryos which contained inside cells it was found that the inside cells were produced by one of the first four 8-cell-stage blastomeres to divide.
The inside cells of 9- to 256-cell embryos had a significantly higher labelling index than the outside cells and the number of inside cells increased faster than the number of outside cells during development. We concluded that the inside cells were dividing faster than the outside cells.
Blastocysts which had developed in vivo or in vitro contained nuclei with greater than 4C amounts of DNA. We concluded that the development of excess DNA amounts does not depend on the maternal environment. These nuclei which contained greater than 4C amounts of DNA were labelled after short exposures to radioactivity. We concluded that it was likely that they were becoming polyploid.
An in vitro study of functions of embryonic membranes in the rat
Authors: Payne G. S. , Deuchar E. M. 
Published: April 2021

ABSTRACT
Ten-day rat embryos have been cultivated in vitro, with different layers of the extra-embryonic membranes removed. The effects of presence or absence of each membrane on the morphology of the embryos, their histodifferentiation and their uptake of leucine into protein have been followed.
Explants with all membranes left intact failed to expand fully and to undergo axial rotation of the embryo, but nevertheless showed highest total protein and highest leucine uptake in biochemical estimations and in autoradiographs.
Explants with outer membranes removed and the visceral yolk sac left intact showed the most normal morphology and expansion of the extraembryonic cavities when compared with embryos removed from the uterus at 11·5 days’ gestation, but they showed less protein and less leucine uptake than the first series.
Explants in which the visceral yolk sac was removed underwent little growth or development and had low total protein values and radioactivity counts. The amnion collapsed and the amniotic cavity disappeared. When the amnion was removed there was a greater incidence of death, as well as little or no development, and lower radioactivity counts than in the first two series.
It is concluded that the outer membranes and the visceral yolk sac play an important role in the transfer of small metabolites to the embryo, as well as in regulating the volume of the extraembryonic fluids.
The isolation and properties of a clonal tissue culture strain of pluripotent mouse teratoma cells
Authors: Evans Martin J. 
Published: April 2021

ABSTRACT
A clonal tissue culture strain of pluripotent cells has been isolated from a transplantable teratoma of inbred strain of mice 129 Sv-S1j CP. This cell strain SIKR when re-inoculated into mice produces teratomas containing at least ten types of tissue. Sub-clones have been isolated and two types distinguished.
(1) ‘C-type’ with a densely-piled in vitro growth. These are tumourigenetic and pluripotent displaying a comparable range of differentiation to the original SIKR.
(2) ‘E-type’ spreading, often epithelioid growth. These grow to a lower density in culture than ‘C-type’. Mostly non-tumourigenetic; in those cases where a tumour has been obtained it did not display multiple differentiations.
The results are interpreted as demonstrating that the culture consists of equivalently pluripotent cells which may become determined and differentiate spontaneously in vitro into slower growing cell types which are continuously overgrown by the culture.
The uptake and transfer of radioactive compounds in axial grafts ofHydra
Authors: Olson J. A. 
Published: April 2021

ABSTRACTHydra littoralis and H. attenuata were labelled with 45Ca, 32PO4, or [3H]thymidine, either by exposing them to a medium containing the isotope or by injecting the isotope into their gut cavities. Various portions of labelled and unlabelled hydra were grafted together in diverse combinations, and the rate of transfer of radioactivity to the unlabelled portion was assessed. The relative transfer rates of the isotopes were 32PO4 &gt; 45Ca2+ ⪢ [3H]thymidine. The transfer rates for 32P-labelled compounds and 45Ca were unaffected either by the polarity gradient (from head to foot and vice versa) or by the existence of potentially separate biological fields. Isotopes were not readily transferred between hydra or pieces of hydra which were in apposition but not grafted together. A rapid and sensitive method for the measurement of hydra mass is also described.
A structural analysis of congenital limb deformities in experimental hyperthyroid tadpoles
Authors: Sit K. H. , Kanagasuntheram R. 
Published: April 2021

ABSTRACTAn experimental model for the study of hyperthyroidism in embryonic development was achieved in the local anuran larvae, Bufo melanostictus, by treatment with potassium perchlorate at a critical dose and time of embryogenesis.Phocomely-hemimely and digital deformities of foreand hind limbs in high percentages of the population were found associated with such critically stimulated tadpoles. Similar deformities were reproduced by exogenous treatment with L-thyroxine sodium. The deformities were severely aggravated if the tadpoles had anti-thyroid treatment before critical stimulation with thyroxine in the sensitive phase of development.Incoordinate cellular differentiation in the malformed limbs was indicated histologically by undifferentiated mesenchyme in the distal extremities although the overlying ectoderm had already formed mature epidermis with specialized skin glands. The differentiated mesodermal components (muscles, cartilages and connective tissues) more proximally were afflicted with degenerative changes. Lytic spinal motor neurones and involuted Mauthner’s neurones with precipitate metamorphosis were accompanying features. Embryonic thyrotoxicosis is discussed in relation to congenital deformities of limbs.
Elektrolytveränderungen in Amphibiengeweben während der Larvenentwicklung, Metamorphose und Regeneration (Xenopus laevisDaudin undTriturus cristatus carnifex)
Authors: Burkart Von T. 
Published: April 2021

ABSTRACTChanges of electrolyte content in amphibian tissues during larval development, metamorphosis and regenerationMeasurements of sodium-, potassium- and water-content were made in amphibian tissues during normal postembryonic development and during various regenerative processes, specifically: (a) of whole larvae of Xenopus laevis curing larval development and metamorphosis, (b) of normally-growing hindlimbs of Xenopus laevis during larval development and metamorphosis, (c) of trunk and the tail, respectively, of X. laevis during the metamorphic climax, (d) of regenerating hindlimbs of Xenopus larvae, (e) of regenerating forelimbs of adult Triturus cristatus carnifex and (f) of heteromorphically regenerating forelimbs of adult X. laevis.Drastic changes in electrolyte concentration were observed for all developmental processes studied and characteristic changes for certain developmental subprocesses like cell accumulation, proliferation and differentiation (see Table 2).The changes in growth-rate (as measured by increase in dry weight) are compared with the changes in K/Na ratio in Xenopus larvae during prometamorphic development and in normally-growing Xenopus hindlimbs. The changes in growth-rate are positively correlated with the changes in K/Na ratio (Figs. 2, 4).Mitotic activity in the normally-growing hindlimbs of Xenopus larvae and in regenerating forelimbs of adult Triturus was studied and compared with the changes in K/Na ratio. It was found that with increasing K/Na ratio the mitotic rates also increased, but beyond a certain level the mitotic frequency decreased (Figs. 4, 11).The beginning of cell differentiation in normally-growing hindlimbs of Xenopus (Figs. 3,4), in regenerating hindlimbs of Xenopus larvae (Figs. 8, 9) and regenerating forelimbs of adult Triturus (Figs. 10,11) is concomitant with an increase in the potassium concentration and the K/Na ratio.The possibility that electrolytes serve as regulators of growth and differentiation processes is discussed.
A decolorant of the sulfhydryl reagent DTNB released from live blastulae of sea urchins in saline medium
Authors: Wolfson N. 
Published: April 2021

ABSTRACT
Cleaving embryos of the sea urchin Paracentrotus lividus exposed briefly to buffered saline release materials into the medium which will bleach a yellow mixture of DTNB and DTT [5,5’ -dithiobis (2-nitrobenzoic acid) and dithiothreitol]. The decolorant activity is thermolabile and dialysable. The bleached mixture recolors rapidly on heating, suggesting the breakdown of a complex between the decolorant and the yellow DTNB ion.
The release of decolorants is maximal at the blastula stage, and in Ca-free saline, Tris-HCl pH 7. When various untreated embryonic stages are homogenized with DTNB, the assay for SH is lowest at blastula, suggesting that decolorants in the blastulae interfere with the assay.
Studies on self-differentiating and induction capacities of Hensen’s node using intracoelomic grafting technique
Authors: Viswanath J. R. , Mulherkar Leela 
Published: April 2021

ABSTRACT
Living Hensen’s node of the definitive primitive streak of chick embryo was prepared into ‘sandwiches’ with the competent ectoderm and the sandwich grafts were transplated into the 2·5 day chick embryo using the intracoelomic grafting technique of Hamburger.
One hundred and twenty-four grafts were prepared and transplanted intracoelomically, 28 grafts were lost due to the death of the host embryos, 63 grafts did not differentiate at all, but 33 well-defined grafts were recovered, after cultivating the transplanted hosts for 12–14 days.
All kinds of tissues from feather germs to neural tissue were found to have differentiated in the grafts. The more frequently occurring tissues were feather germs, epidermal vesicle, neural tissue, kidney and muscle. Other differentiations were the cartilage notochord and gut. No definite combination pattern has emerged from the tissues. But when the tissues were traced to their germ-layer derivation, 22 of them belonged to the mesodermal complex, 11 to the ectodermal complex and 8 to the endodermal complex.
In the light of the above results, the probable existence of a mesodermal factor and an ectodermal factor independently responsible for the respective differentiations, as also the competence of the ectoderm, is discussed.