bluuebunny/crossref_metadata_2025_split huggingface dataset:
Erratum; The role of extra-cellular matrix in the formation of the sclerotome
Authors: Solursh Michael , Fisher Marilyn , Meier Stephen , Singly Karl T. 
Published: April 2021

ABSTRACT
J. Embryol. exp. Morph. 54, 75– 98 (1979)
The Editors regret that Figures 2–6 of the above paper contained inaccuracies. The revised version of this plate is published here.
Distal regeneration in proximal fragments of the wing disc ofDrosophila
Authors: Karlsson Jane 
Published: April 2021

ABSTRACTThe rules governing proximo-distal regeneration in the wing disc of Drosophila were investigated. It was found that proximal fragments confined to either anterior or posterior compartments could not regenerate distally, although many fragments having tissue from both compartments could do so even in the absence of circumferential regeneration. Fragments containing the ventral but not the dorsal end of the anterior-posterior border were able to regenerate distally. The use of a cuticular marker in the posterior compartment very close to the border permitted precise localization of the tissue required to cause anterio fragments to regenerate distally; in anterior fragments cut close to the border, there was an almost perfect correlation between possession of this marker and distal regeneration. It was found however, that distal regeneration was not an all-or-none phenomenon; its extent was dependent on the total amount of tissue present from both compartments.
The changes in lectin activity during the development of embryonic chick skin
Authors: Kitamura Kunio 
Published: April 2021

ABSTRACTChanges in lectin activity during development of embryonic chick skin were studied. In the dorsal skin of the chick embryo in which feathers were formed, lectin activity first increased, during the period of dermal condensation, and then it decreased during the development of feathers. A similar change in lectin activity was also found in the anterior shank skin, the prospective scale region of the chick embryo. The embryonic cornea, in which no mesenchymal condensation took place, had lectin activity and did not show any developmental changes in lectin activity. Apteria regions of the dorsal skin, experimentally formed by treatment with hydrocortisone, gave low lectin activity. The lectin found in the embryonic skin showed specificity for lactose. The relationship found between lectin activity and dermal condensation in the embryonic chick skin is discussed.
Preimplantation development of microsurgically obtained haploid and homozygous diploid mouse embryos and effects of pretreatment with Cytochalasin B on enucleated eggs
Authors: Modliński Jacek A. 
Published: April 2021

ABSTRACT
Haploid embryos were obtained by microsurgical removal of one pronucleus, followed by doubling of the haploid chromosome set with Cytochalasin B (CB), either at the first or second mitosis. This procedure provides a source of fully homozygous diploid embryos, which were grown in vitro or in vivo. The effect of CB treatment before and during operation on the course of enucleation and further development of embryos was studied. Out of 81 eggs made diploid at 2-cell stage and transplanted into the oviducts of immature or pseudopregnant recipients 27 morulae and blastocysts were recovered, but not a single case of implantation occurred by the eighth or ninth day of development. After 72–80 h of in vitro culture, most of the homozygous embryos were morulae but after an additional 24 h the majority of them transformed into blastocysts. The rate of development of homozygotes was markedly better than that of haploids, which progressed beyond morula stage. The immediate survival rate of operated eggs was dependent on whether or not the eggs were pre-incubated and the enucleation was performed in the presence of CB. In the former case the immediate survival rate was nearly twice as high as in the absence of CB, but more of the treated eggs underwent fragmentation and early developmental arrest.
The cellular basis of epiboly: An SEM study of deep-cell rearrangement during gastrulation in Xenopus laevis
Authors: Keller R. E. 
Published: April 2021

ABSTRACT
Measurements of several indices of shape, contact, position and arrangement of deep cells in the late blastula and gastrula were made from scanning electron micrographs of carefully staged, fractured embryos in order to describe the cellular processes which account for the increased area of the deep region of the gastrula during extension of the dorsal marginal zone and epiboly of the animal region. At the onset of gastrulation, the deep cells of the dorsal marginal zone become elongated, extend protrusions between one another along radii of the embryo and interdigitate to form fewer layers of cells of greater area in a process of radial interdigitation. When interdigitation is complete, the deep region consists of one layer of columnar cells which then flatten and spread and thus account for additional increase in area of the deep region. During epiboly of the animal region, interdigitation occurs and the number of cell layers decreases without the changes in cell shape seen in the dorsal marginal zone. These differences may be related to the anisotropy of expansion (extension and convergence) in the dorsal marginal zone as opposed to uniform spreading in the animal region, or they may reflect an active cell motility in the dorsal marginal zone as opposed to a passive behavior in the animal region. A cellular and mechanical model is presented in which active (autonomous) spreading is brought about by active, force-producing interdigitation and subsequent flattening of deep cells. A model of passive spreading (stretching) is also presented. These observations suggest experiments that would determine the relationship of cell behavior to the mechanics of gastrulation.
Induction of supernumerary tracheal buds and the stimulation of DNA synthesis in the embryonic chick lung and trachea by epidermal growth factor
Authors: Goldin Geoffrey V. , Opperman Lynne A. 
Published: April 2021

ABSTRACT
Epidermal growth factor (EGF) has been found to stimulate DNA synthesis in both the trachea and bronchial tree of 5-day-old chick embryo lung rudiments in organ culture. After 20 h culture in the presence of 10 ng/ml EGF, the incorporation of tritiated thymidine into DNA is stimulated two- to three-fold following a 2 h labelling period, as revealed by scintillation counting. Autoradiographic data indicate that this stimulation is most marked in the epithelial tissue component of both the trachea and bronchial tree. Supernumerary ‘lung’ buds have been induced in the normally unbranched tracheal epithelium by agarose pellets containing EGF, such buds having been previously induced only by grafting a variety of mesenchymal tissues alongside the tracheal epithelium. Since EGF has been shown to be a potent stimulator of tracheal DNA synthetic activity it is suggested that the induction of supernumerary buds by the EGF-agarose pellets is achieved through a localized stimulation of cell proliferation in the tracheal epithelium. These data would further suggest that the induction of supernumerary tracheal buds by various mesenchymal tissues is similarly due to a localized increase in mitotic activity resulting from the action of some mitotic stimulator substance(s) emanating from the inducing mesenchymal tissue. This conclusion may be extended to include normal bud formation which occurs during branching morphogenesis in everal developing organ systems.
Correlative light and electron microscopy of dissociated immature rat testicular cells undergoing morphogenesis in vitro
Authors: Erickson L. A. , Davis J. C. , Burton P. R. , Snyder J. 
Published: April 2021

ABSTRACT
Immature rat testicular cells undergo morphogenesis in primary culture (Davis, 1978). Depending upon the number of dissociated testicular cells added to the culture dish, spherical or tubular aggregates were formed. Spherical aggregates resulted from movement of cells into centers of aggregation and the detachment of these cells from the substratum; on the other hand, tubular aggregates resulted from detachment and retraction of the cell monolayer at certain points along its outer edge. In this investigation, the different methods of formation of aggregates by immature rat testicular cells in primary culture were examined with the scanning electron microscope (SEM). The cell types involved in such morphogenesis and their associations within completely formed structures were examined by transmission electron microscopy (TEM). In addition, the rates of formation of aggregates were established by time-lapse cinemicroscopy. During formation of spherical aggregates, the rate of recruitment of cells into centers of aggregation (0·04 ± 0·006 μm/min; x̄ ± S.E.M., n = 78) was much slower than the rate of cell detachment during formation of tubular aggregates (11·7 ± 1·8 μm/sec; x̄ ± S.E.M., n = 110).
Although specific roles for each cell type in formation of aggregates have not been determined, the associations of cells within the two types of reformed aggregates appeared to be similar. Myofibroblast cells were located in outer cell layers and Sertoli cells were observed to underlie the layers of myofibroblasts in both types of aggregates. Germinal cells, however, were found on the outer surface of spherical aggregates, but in tubular aggregates they were located on the inner surface. Since spherical and tubular aggregates are formed by different methods, this observation suggests that rearrangement of cells within the aggregates takes place and contributes to the internal morphology of newly-formed aggregates.
Evidence that the premature death mutation (p) in the Mexican axolotl (Ambystoma mexicanum) is not an autonomous cell lethal
Authors: Mes-Hartree Mary , Armstrong John B. 
Published: April 2021

ABSTRACT
Cell-lethal developmental mutations, which are presumed to affect the viability of all cells in a mutant embryo, have been distinguished from other developmental lethals on the basis of the results of parabiosis and transplant experiments. Premature death (p), previously classified as a cell lethal, does not survive parabiosis. However, transplants involving mutant eye, flank epidermis and primordial limb tissue all survived on a normal recipient. The mutant, therefore, cannot be considered a true cell lethal, though it suffers from serious and widespread abnormalities that cannot be corrected by parabiosis. In addition, transplants of mutant branchial mound tissue did not develop into normal gills on a normal recipient. These transplants were the only ones involving mutant endoderm, and their failure supports our hypothesis that the mutation leads to a specific endoderm defect.
Paternal gene expression in developing hybrid embryos of Xenopus laevis and Xenopus borealis
Authors: Woodland H. R. , Ballantine J. E. M. 
Published: April 2021

ABSTRACT
We have studied protein synthesis in the viable hybrid Xenopus laevis (♀) × Xenopus borealis (♂) using 2D gel electrophoresis. Fourteen borealis-specific proteins were studied. Two of these proteins appeared by the gastrula stage, five in the gastrula and the rest later. Where homologous laevis proteins were tentatively identified, androgenetic haploid hybrids were used to study whether the protein was encoded by stored maternal mRNA, and how long this mRNA persisted. The two proteins appearing in blastulae were probably initially coded by stored maternal mRNA. This was not detectable by the tailbud-tadpole stage, and presumably had been destroyed.
Hormonal control of head-wart development in the snail, Euhadra peliomphala
Authors: Takeda Naokuni 
Published: April 2021

ABSTRACT
The terrestrial snail, Euhadra peliomphala, has a peculiar organ between the optic tentacles named the head-wart, which releases a sex pheromone just before courtship. The development of the head-wart was closely correlated with the sexual maturity of the snail. Castration led to the atrophy of the head-wart. Subsequent injection of hermaphrodite gland homogenate into the body cavity of castrated individuals induced the development of the head-wart. The peripheral regions of the acini in the hermaphrodite gland showed a positive reaction for 3β-hydroxy steroid dehydrogenase. Furthermore, preliminary radioimmunoassay also showed that the hermaphrodite gland of the snail contained testosterone and estradiol. When the immature head-wart was cultured for 10 days in a medium containing testosterone and estradiol respectively, development of the head-wart was found only in medium containing testosterone. From these results, it is concluded that head-wart development in the snail, Euhadra peliomphala, is under direct control from the hermaphrodite gland, probably by means of testosterone.
Role of the kidney in foetal erythropoiesis: Erythropoiesis and erythropoietin levels in newborn mice with renal agenesis
Authors: Hågå Per , Kristiansen Stein 
Published: April 2021

ABSTRACT
The role of the kidney in foetal erythropoiesis was studied in newborn SD mice on the day of birth. Some of the homozygotes and heterozygotes of this strain are born anephric. Red cell production was evaluated by haematocrit levels, reticulocyte counts, and Fe59-uptake in liver and RBC, the isotope given to the mothers during pregnancy.
Erythropoiesis of the newborn with renal agenesis was not different from that of animals with intact kidneys. When the mothers were exposed to hypoxia during pregnancy, significantly higher haematocrit- and reticulocyte levels were observed, and there was no difference in erythropoiesis of anephric newborn compared with newborn with intact kidneys. Red cell production was also similar in those with and without kidneys when the mothers were hypertransfused.
Plasma erythropoietin levels in the offspring of normal pregnancies were determined. Detectable concentrations of the hormone were found, and the levels were the same in anephric and normal newborn. Exposure to hypoxia (0-5 atm for 6 h) significantly increased plasma erythropoietin levels. This increase was of the same magnitude in animals with and without kidneys.
This study indicates that murine foetal erythropoiesis is regulated by erythropoietin in the same way as later in life. Since abolition of the erythropoiesis of the mothers through hypertransfusion, did not influence the red cell production of the foetuses, Ep seems not to cross placenta. Erythropoietin is, therefore, produced extrarenally during this period.
Evidence for a metameric pattern in the development of the chick humerus
Authors: Stephens Trent D. , McNulty Teresa R. 
Published: April 2021

ABSTRACT
It has been proposed that the wing bud is induced by some axial influence at a specific confined location and that the ZPA is the residual influence of such induction. The purpose of the present investigation was to test this hypothesis. Tantalum foil barriers were placed lateral to the mesonephric duct and parallel to the long axis of the embryo in the wing field of stage-12 to -15 chick embryos. These barriers blocked the somatopleure’s communication with more medial tissues at specific somitic levels. The results of these experiments demonstrate that (1) the limb is not induced at one specific point, (2) portions of the humerus appear to be induced segmentally along the entire limb field and (3) the ZPA is not induced by axial structures. We propose a model of wing development suggesting that the humerus is induced as several separate components which then fuse to form the definitive bone.
Ionic induction of the frog cement-gland cell from presumptive ectodermal tissues
Authors: Yoshizaki Norio 
Published: April 2021

ABSTRACT
Cells of the superficial layer which had been explanted from the presumptive ectoderm of Rana japonica early gastrulae at stage 10 differentiated into cement-gland cells (CGCs) when cultured in Barth’s solution containing 90–130 mM-NaCl., and into common epidermal cells and cilia cells when cultured in a solution containing 20–40 mM-NaCl. They failed to differentiate, however, when cultured in a solution in which NaCl is 15 mM or lower.
The optimum condition for inducing the differentiation of CGC was stimulating them with a solution containing 130 mM-NaCl for 6–10 h at 18 °C, followed by culturing in a solution containing 15–40 miu-NaCl for 7 days. The greatest ability to react to the CGC-inducing stimuli resided in the superficial layer of the presumptive ectoderm of the embryo at stages 10–11. Under the optimum condition, the total volume of CGCs induced amounted to about 85% of the explanted tissue. High percentage comparable to this was obtained with stimulation by KC1, RbCl, sucrose or mannitol.
The distribution of regenerative potential in the wing disc ofDrosophila
Authors: Karlsson Jane 
Published: April 2021

ABSTRACTThe distribution of regulative potential was investigated in the wing disc of Drosophila. Ten complementary pairs of fragments were tested for their capacity to regenerate or duplicate. The distribution of positional values resulting from this data was found to be very unequal; six of the twelve clockface values were tightly clustered round the anterior-posterior compartment boundary. Despite this, complementarity between regeneration and duplication was generally maintained.
Morphogenetic analysis of changing cell associations following release of 2-cell and 4-cell mouse embryos from cleavage arrest
Authors: Kimber S. J. , Surani M. A. H. 
Published: April 2021

ABSTRACTTwo-cell and four-cell mouse embryos were cultured in Cytochalasin D (CD) for 40–48 h. They were fixed for light and electron microscopy at various times after washing off the CD. Cleavage-arrested embiyos in CD had well separated blastomeres but by 1 h from washing the embryos had compacted, in most cases without undergoing cell division. By 2 h after release from arrest one blastomere of the 2-cell arrested embryos had become crescent shaped and at 4–5 h the crescent-shaped blastomere had started to spread over the surface of the other rounded blastomere. This process continued until by 16–24 h from explantation to fresh medium one blastomere had almost completely engulfed the other. A similar process occurred in 4-cell arrested and released embryos. At this stage the embryos had accumulated fluid and become blastocyst-like vesicles. In 20% of 2-cell and 4-cell embryos one or two blastomeres underwent one cell division after release from arrest. Serial sections of these embryos lead to the conclusion that one or both progeny of the first cell to divide tended to be engulfed by the later dividing or non-dividing cell(s). These results are discussed in relation to the differentiation of ICM and trophectoderm in blastocysts.
Blastokinesis in embryos of the bug, Pyrrhocoris apterus.: A light and electron microscopic study 1. Normal blastokinesis*
Authors: Enslee Eugenie C. , Riddiford Lynn M. 
Published: April 2021

ABSTRACT
In the bug, Pyrrhocoris apterus, blastokinesis (a reversal of the position of the embryo within the egg) is seen to involve contraction of the serosa that is attached to the embryo’s head. As the serosal cells change from squamous to columnar in the course of blastokinesis, a dense zone of microfilaments appears just under the apical surface. Many apical protrusions develop above this zone. After the embryo is in its final position the zone disappears and later the cells degenerate.
Laterally, the serosal cells are connected by belt desmosomes, septate junctions and gap junctions. As blastokinesis progresses, more lateral surface is recruited below them from the original basal surface.
Microtubules running parallel to the plasma membrane are seen near the apical microfilaments and along other surfaces of the cell. Secretory granules are evident both within serosal cells and along the apical surface, probably providing a lubricant for movement against the chorion. Yolk cells are common basal to the serosa, possibly mobilizing nutrients for it.
This study of blastokinesis in Pyrrhocoris provides a dramatic example of cell shape change that is correlated with the appearance of microfilaments. In its details blastokinesis is comparable to morphogenetic events such as amphibian neural tube formation and ascidian metamorphosis.
The age-dependent loss of cells from the rear of aDictyostelium discoideumslug is not tip controlled
Authors: Smith Elizabeth , Williams Keith L. 
Published: April 2021

ABSTRACTYoung slugs of the cellular slime mould Dictyostelium discoideum drop small numbers of individual amoebae (∼ 10/mm) in the slime trail. With increased time of migration, slugs develop trailing tails and leave clumps of cells in their slime trails. Using reciprocal transplants between tips of young and old slugs and between a wild-type strain and an ‘aged” mutant it was shown that this age-dependent cell loss is due to changes in the bulk of cells comprising the slug, rather than to changes in the effectiveness of the tip (organizer region). Another property of the slug, the decision to continue migrating or form a fruiting body which is controlled by the tip, was less affected by age. This raises the possibility that cell autonomous properties of the slug are more subject to ageing than is the tip.
The development of the retinotectal projections from compound eyes in Xenopus
Authors: Straznicky C. , Gaze R. M. , Keating M. J. 
Published: April 2021

ABSTRACT
The retinotectal projections from double-nasal (NN), double-temporal (TT) and double-ventral (VV) compound eyes in Xenopus were studied autoradiographically and electrophysiologically during development. Early TT projections were confined to rostrolateral tectum and spread with advancing age to cover most of the tectum by shortly after metamorphosis. Early VV projections showed a decreased density of label on lateral tectum. Early NN projections appeared to extend across the entire rostrocaudal length of the available tectum at all stages of development, but showed a decrease in label density on rostral tectum. The results are discussed in relation to various hypotheses about the formation of retinotectal connexions.
Effects of biochemical inhibitors on positional signalling in the chick limb bud
Authors: Honig Lawrence S. , Smith J. C. , Hornbruch Amata , Wolpert L. 
Published: April 2021

ABSTRACT
In 3- to 4-day embryonic chick limb buds, a region at the posterior margin of the limb, the zone of polarizing activity, appears to be responsible for signalling positional information along the anteroposterior axis. Our experiments were designed to test which biosynthetic processes are required for polarizing activity. We have treated polarizing regions with biochemical inhibitors, and then assayed their abilities to induce limb reduplications when grafted into anterior sites on host limb buds, and also measured their capacities for protein, RNA, and DNA synthesis. DNA synthesis, and possibly oxidative phosphorylation, do not seem to be required for polarizing activity. But, glycolysis and protein and RNA synthesis are necessary, although not sufficient, for polarizing region activity. Activity seems particularly sensitive to inhibitors (actinomycin D and a-amanitin) of RNA synthesis.
Cytoplasmic polarity develops at compaction in rat and mouse embryos
Authors: Reeve W. J. D. 
Published: April 2021

ABSTRACT
Cells of both rat and mouse morulae can be stained vitally to reveal an asymmetry in the organization of their cytoplasm. In each cell of the rat 8-cell embryo a column of organelles develops between the nucleus and the embryo periphery as revealed by toluidine blue, acridine orange and horseradish peroxidase (HRP). Although cells of the mouse morula lack the blatant asymmetric distribution of organelles observed in rat cells, a long pulse (&gt; 3 h) of HRP to compact 8-cell mouse embryos revealed a distinct restricted localization of the enzyme not evident at earlier pre-compaction stages. The cytoplasmic polarity generated in these embryos can be demonstrated in cells of intact embryos, and also in cells disaggregated from embryos before vital staining.