bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reversal of developmental competence in inverted amphibian eggs
Authors: Chung Hae Moon , Malacinski George M. 
Published: April 2021

ABSTRACT
Inverted amphibian embryos were employed for an analysis of pattern formation in early embryogenesis. Axolotl (Ambystoma) and Xenopus eggs were inverted prior to the first cleavage division and permitted to develop upside down to the early gastrulation stage. In both cases the cleavage patterns of the animal and vegetal hemispheres were reversed. By gastrulation, however, developmental arrest began, and no inverted embryos developed beyond neurulation. The state of competence of the animal and vegetal hemisphere cells of inverted embryos was examined in a series of tissue transplantations, usually into genetically marked (albino) hosts. In all cases the developmental competence of the original animal and vegetal hemisphere cells of inverted embryos had been reversed. For example, the egg’s original vegetal hemisphere developed into various neural structures.
Those observations should eventually be useful in formulating models to account for the manner in which various regions of the amphibian egg cytoplasm generate early embryonic patterns.
Determination of the curvature of epithelial cell mass by mesenchyme in branching morphogenesis of mouse salivary gland
Authors: Nogawa Hiroyuki 
Published: April 2021

ABSTRACT
Mouse submaxillary epithelium undergoes branching morphogenesis with increase in the curvature of its surface in vivo. Recombination experiments in vitro of the epithelium and mesenchyme between 13- and 14-day rudiments showed (1) that the 14-day mesenchyme more actively induced the epithelium to branch than the 13-day mesenchyme, (2) that the 14-day mesenchyme could produce clefts on smaller epithelial lobes than the 13-day mesenchyme, (3) that the 14-day mesenchyme produced lobes with similar diameter to lobes of the 14-day intact rudiment, and (4) that the lobular morphology of assembled 14-day lobes became obscure in recombinates with the 13-day mesenchyme while it was well maintained in recombinates with the 14-day mesenchyme. From these results it is concluded that the mesenchyme determines the curvature of epithelial surface, and that clefts are formed on the epithelial surface as a result of increase in the epithelial curvature.
Positional information in the forelimb of the axolotl:properties of the posterior skin
Authors: Slack J. M. W. 
Published: April 2021

ABSTRACTTwo series of experiments were carried out to investigate the properties of the positional information carried by posterior skin of the axolotl forelimb. The skin was assayed by grafting it to the anterior side of a normal limb and then amputating through the graft region. The formation of a double posterior regenerate indicates that the grafted skin carried the posterior coding.In the first series, double posterior limbs were created by grafting posterior half limb rudiments to the flank of tailbud-stage embryos. The animals were reared for several months and then a half cuff of anterior skin, judged in relation to the whole body axes, was assayed by grafting to one of the host limbs. The results show that both sides of the double posterior limb carry the posterior coding and confirm our expectation that the visible anatomy is a good guide to the underlying codings.In the second series animals were prepared by embryonic grafts so that they bore an extra normal limb on the flank. This extra limb was marked by pigmentation and in some cases by triploidy. When the limbs had developed, posterior skin from the extra limb was grafted to the anterior side of a host limb. The host limbs were amputated at intervals ranging from 2 weeks to 1 year after the skin graft. The results show that the posterior coding carried by the graft is stable even in an anterior environment.Studies of the cellular composition of regenerates which had received triploid grafts showed that the graft epidermis was progressively replaced by that of the host. The dermis on the other hand retained triploid cells throughout.
Segregation of germline granules in early embryos ofCaenorhabditis elegans: an electron microscopic analysis
Authors: Wolf Nurit , Priess James , Hirsh David 
Published: April 2021

ABSTRACTUsing an improved fixation method for electron microscopy, we have found germline granules in Caenorhabditis elegans embryos shortly after fertilization and prior to the first cleavage. They are localized in the egg cytoplasm which becomes segregated into the posterior blastomere at the first cleavage. In the following divisions, the granules continue this pattern of asymmetric segregation and are ultimately segregated into the germline precursor cell. The granules are then symmetrically segregated into the germline cells.
Lumen formation in the developing mouse mammary gland
Authors: Hogg N. A. S. , Harrison C. J. , Tickle C. 
Published: April 2021

ABSTRACT
The mammary gland is a system of hollow interconnecting tubes which develops from an invasive branching cord of epithelial cells. This ultrastructural study of the developing mammary gland focuses on how the lumen forms and establishes the polarized epithelial lining of the gland. The earliest signs of lumen formation are many small cavities and crevices lined with microvilli which appear at scattered sites throughout the branching cords and neck of the gland. It is suggested that these initial small lumina form quite simply by separation of cells whose opposing faces are non-adhesive. The continuous central lumen of the gland develops by fusion and enlargement of the many small lumina. The cells adjacent to the developing lumen will form the polarized epithelial lining of the gland. Excess, more basal, epithelial cells degenerate.
The lumen begins to appear when the branching pattern is almost complete. Thus, during morphogenesis, invasion by the mammary gland epithelium involves penetration of the mesenchyme by a solid cord of cells. We suggest that this cellular organization may be a fundamental characteristic of invasive epithelia and that a crucial step in the development of malignant epithelial tumours is a change in cell organization from a polarized cell sheet to a solid cord of cells which can invade.
The origin of the ectomesenchymal condensations which precede the development of the bony scleral ossicles in the eyes of embryonic chicks
Authors: Fyfe D. M. , Hall Brian K. 
Published: April 2021

ABSTRACT
The origin of neural crest-derived ectomesenchymal condensations located subjacent to scleral papillae and the development of the more deeply situated scleral ossicles were investigated in scleral tissues explanted from the eyes of chick embryos at Hamburger & Hamilton (1952) stages 30-38 ( days of incubation). Explants were pulse labelled with [3H]thymidine for 4h in vitro. Nuclear counts and % labelling indices were calculated for standardized areas within and between the condensations. At all stages exhibiting condensations, the % labelling indices were higher within the condensations than in tissues between condensations. % labelling declined with maturity, but the decline was greater between than within condensations. Regional differences in intensity of proliferation in the ectomesenchyme centred about the scleral papillae seemed to be the best explanation for the development of these condensations. The condensations disappeared concommitant with the complete degeneration of the adjacent papillae. A new distribution of labelled nuclei 70-100 μm deep in the tissue and beneath the original sites of the condensations preceded the appearance of ossicle primordia. The roles of the scleral papillae, the ectomesenchymal condensations and deeper primordia in the development of scleral ossicles are discussed.
Structure of normal and polyoma virus-transformed hamster cell cultures
Authors: House W. , Stoker M. G. P. 
Published: April 2021

ABSTRACT
Vertical sections of colonies and confluent sheets of normal and polyoma virus-transformed BHK21 cells, and of a spontaneous malignant variant of BHK21 cells, and also of freshly isolated hamster fibroblasts, were examined to determine the structural interrelationship of the cells in relation to their varying transplantability.
All cells except the freshly isolated fibroblasts formed multilayers, but the virus-transformed cells were arranged in the form of a loose network, in which cell division took place. The untransformed BHK21 cells were very tightly packed and mitosis was rare. A spontaneous malignant variant which superficially resembled the normal BHK21 cells was shown by section to have features in common with virus-transformed cells.
Studies on Internal Secretion II. — Endocrine Activity in Fœtal and Embryonic Life
Authors: Hogben Lancelot T. , Crew F. A. E. 
Published: April 2021

ABSTRACT
The time at which the fœtal thyroid and pituitary glands in sheep and oxen can be shown to contain secretory products as inferred by their action upon amphibian development and colour response conforms to what might be anticipated on histological grounds: neither experimental nor microscopic data provide any justification for attributing the ætiological significance of the monstrous abortive Dexter calf to thyroid deficiency. Preliminary experiments suggest the desirability of using the embryo chick for studying the correspondence between secretory activity and histological structure in the case of the adrenals.
Polyploidy
Authors: Gates R. Ruggles 
Published: April 2021

ABSTRACT
By polyploidy is meant an increase in the number of sets of chromosomes in a plant or animal. The bodies of animals and of the higher plants normally contain two sets of chromosomes, one derived from each parent. In ordinary sexual reproduction this number is reduced to one half in the maturation of the germ cells, and the diploid or 2x number is restored in the process of fertilisation by the union of two germ cells whose nuclei are each carrying the haploid or x number. But the comparative study of chromosomes shows that there are many instances in plants and animals where additional sets of chromosomes have been acquired by the organism, thus giving rise to species, genera, or individuals which are triploid (3x), tetraploid (4x), pentaploid (5x), hexaploid (6x), or even decaploid (10x) in their chromosome outfit. These conditions of polyploidy have a number of interesting consequences and evolutionary bearings which it is the purpose of this article to discuss.
The Chemotaxis of Spermatozoa and its Questioned Occurrence in the Animal Kingdom
Authors: Dakin William J. , Fordham M. G. C. 
Published: April 2021

ABSTRACT
The experiments fully detailed above need little summing-up, since the general result has been appended to each.
The discoveries may be tabulated as follows :-
Capillary tubes containing sea-water which has been in contact with ripe eggs of Echinus esculentus soon become plugged with spermatozoa when immersed in a sperm suspension. Control tubes containing normal sea-water, cœlomic fluid, sea-water of different PH and sea-water with immobilising reagents, etc., never contain anything like the same number of sperms as the egg-water tubes. The above result, obtained regularly, is quite contradictory to those of Buller and Loeb on other species of Echinoderms. From the general appearance of the accumulation of sperms, from the fact that a greater length was travelled in the egg-water tubes than in the others, and from the results with capillary tubes containing immobilising reagents, we consider that Echinus esculentus eggs give off substances which actually direct the sperm movements; in other words, that chemotaxis is demonstrated. The results of Experiments X. and XI. show that in all probability the accumulation of sperms in capillary tubes containing egg-water is due not only to chemotaxis, but also to other phenomena which it is known are produced by egg secretions (aggregation and agglutination of spermatozoa). The chemotactic action of egg-water seems to be specific. Egg-water of similar PH from Echinocardium cordatum had no effect upon sperms of Echinus esculentus. Possibly chemotaxis does not occur in all species of Echinoderms. This might explain the results of Buller and Loeb. It was not demonstrable in Teredo. Moreover, the experiments do not prove that the phenomenon is absolutely necessary for the fertilisation of eggs of Echinus esculentus. On the other hand, they would indicate that chemotaxis does occur in the animal kingdom, and in this respect they support the experiments of Lillie and de Meyer.
Absence of Prenatal Effects of Lens-Antibodies in Rabbits
Authors: Huxley J. S. , Carr-Saunders A. M. 
Published: April 2021

ABSTRACT
The experiments of Guyer and Smith have attracted wide-spread attention. Their results are recorded in two papers (1918 and 1920). The first paper describes the injection of rabbit lens into fowls and the subsequent injection of the sensitised fowl serum so produced into pregnant does. Some of the young of the treated does exhibited certain abnormalities of the eye. No breeding experiments are recorded in this paper. In the second paper a similar series of experiments is described, as a result of which more abnormalities were produced. Breeding experiments with the abnormal young showed that the defects were inherited. In view of the interest which these experiments have aroused, it seemed desirable to repeat them, and this paper records an attempt to do so. The methods used by us were modelled on those employed by Guyer and Smith ; the particulars in which our methods differed from those of these two authors will be indicated in the description of our experiments and attention again drawn to them, so far as the matter seems relevant, in the comparison of our results with those of Guyer and Smith in the discussion which will follow.
Histological Studies on the Gonads of The Fowl
Authors: Fell Honor B. 
Published: April 2021

ABSTRACT(1) The so-called ‘luteal’ cells of the ovary are derived from the medullary cords of the embryo, as previously shown by Firket and Nonidez. The process, which appears to be a peculiar form of fatty infiltration, begins about the eleventh day of incubation. (2) Multiplication of the cells occurs in post-embryonic life and, as suggested by Nonidez, appears to take place not by mitosis but by a neoformation at the expense of certain epithelial elements in the stroma and ovarian thecae, which are derived from the distal extremities of the medullary cords. (3) The fully formed ‘luteal’ cell is seen to have a rather small spherical nucleus and vacuolated cytoplasm, which impregnates very deeply with the Mann-Kopsch and Da Fano techniques, and which contains blocks and granules of mitochondrial origin. With Benda’s stain fat can sometimes be demonstrated in the vacuoles. Golgi bodies are situated round the archoplasm. (4) The formation of ‘luteal’ cells in cases of sex reversal is found to be a repetition of the embryonic process. Sex cords are proliferated into the ovarian stroma and either give rise to seminiferous tubules or remain undifferentiated and form typical ‘luteal’ cells. In the latter case usually many of the neighbouring cords are degenerating. (5) The mode of origin of the ‘luteal’ tissue in the embryos, normal adult and cases of sex reversal, is difficult to reconcile with Morgan’s theory of the endocrine activity of these cells in relation to plumage. (6) In view of Geoffrey Smith’s work on Inachus and Sacculina, it is suggested that the exhibition of hen-feathering may possibly be due to a high lipoid content of the blood. On this assumption, the association of female plumage with the presence of ‘luteal’ cells in the gonad would be explicable, since inactive tissue such as the medullary cord cells would be more prone to fatty degeneration in such hen-feathered individuals. (7) It is thought that Pearl and Boring are mistaken in homologising the ‘luteal’ islets with the cells of the mammalian corpus luteum, since the numerous vacuolated cells of discharged and large atretic follicles are found to be mainly the product of fatty degeneration of ordinary connective tissue elements, while the yellow pigment seems to be derived from aborting blood vessels. This pigment is regarded as hsematoidin and is not found in the true ‘luteal’ cells.
Observations on Amoeba Feeding on The Ciliate Frontonia
Authors: Beers C. Dale 
Published: April 2021

ABSTRACT
Amoeba occasionally feeds on the ciliate Frontonia. In the instances of feeding observed, the Frontonia was not ingested whole but was cut in half by the Amoeba. One half of the Frontonia is engulfed in a food cup of the Amoeba, the pseudopods of the cup producing an annular constriction in the middle region of the ciliate. The pseudopodial collar or cup flows distally and presses against the free half of the Frontonia. Thus the halves are pushed continuously farther apart, until the attenuated interconnecting strand is severed and one-half of the Frontonia is simultaneously engulfed.
Selective Production of 1,3-Butadiene from 1,3-Butanediol over Y2Zr2O7 Catalyst
Authors: Matsumura Yoshitaka , Matsuda Asami , Yamada Yasuhiro , Sato Satoshi 
Published: April 2021

Abstract
The vapor-phase dehydration of 1,3-butanediol (1,3-BDO) to produce 1,3-butadiene (BD) was investigated over yttrium zirconate, Y2Zr2O7, which was prepared through a hydrothermal aging process. 1,3-BDO was initially dehydrated to three unsaturated alcohols, namely 3-buten-2-ol, 3-buten-1-ol, and 2-buten-1-ol, followed by the further dehydration to BD. The catalytic activity of Y2Zr2O7 was strongly dependent on the calcination temperature. Furthermore, the reaction temperature was one of the important factors to produce BD efficiently: the selectivity to BD was increased with increasing reaction temperature up to 375 °C, while coke formation led to catalyst deactivation together with by-product formation at higher temperatures. Y2Zr2O7 catalyst calcined at 900 °C showed a high BD yield of 95% at 375 °C and a time on stream of 10 h.
Diagnostic efficacy of joint ultrasonography, dual-energy computed tomography and minimally invasive arthroscopy on knee gouty arthritis, a comparative study
Authors: Xie Yuesheng , Li Ling , Luo Riqiang , Xu Ting , Yang Lin , Xu Fangping , Lin Haobo , Zhang Guangfeng , Zhang Xiao 
Published: April 2021

Objective:
This study aimed to investigate the diagnostic performance of minimally invasive arthroscopy for knee gout when comparing with joint ultrasonography and dual-energy computed tomography (DECT).

Methods:
From January 2016 to December 2018, 121 inpatients with knee joint swelling and pain were prospectively enrolled, including 63 gout patients and 58 non-gout patients. All patients underwent pre-operative ultrasonography and DECT to evaluate knee joint monosodium urate (MSU) deposits, followed by minimally invasive arthroscopy. The gold-standard for gout diagnosis was defined as the detection of MSU crystals in the synovial fluid under polarizing microscopic or pathological analysis.

Results:
The diagnostic results of ultrasonic double contour sign, hyperechogenic foci, MSU deposition (detected by DECT), MSU deposition (detected by arthroscopy) and MSU deposition in cartilage (detected by arthroscopy) were significantly associated with that of the gold-standard. Except for hyperechogenic foci, the other four indexes had high sensitivity and specificity (approximately or over 80%) and a large odds ratio (OR) (14.73 to 36.56), indicating good diagnostic performance. Detection of MSU deposition in cartilage by arthroscopy had a good diagnostic agreement with the ultrasonic double contour sign (κ = 0.711, p &lt; 0.001).

Conclusion:
Joint ultrasonography, DECT, and minimally invasive arthroscopy had high sensitivity and specificity for the diagnosis of knee gouty arthritis. Minimally invasive arthroscopy was superior to joint ultrasonography and DECT, which can be a useful supplement for the diagnosis of gout.

Advances in knowledge:
This is the first study comparing the diagnostic performance for knee gout among the joint ultrasonography, DECT, and minimally invasive arthroscopy.
Side-by-side evaluation of virtual non-contrast and post-contrast images improves detection of clinically significant urolithiasis on single-phase split bolus dual-energy CT urography
Authors: Dodig Doris , Solocki Matić Tereza , Žuža Iva , Pavlović Ivan , Miletić Damir , Markić Dean 
Published: April 2021

Objectives:
Studies show insufficient sensitivity of virtual non-contrast (VNC) reconstructions for stone detection in dual-energy CT urography (DE-CTU). The aim of this study was to investigate if side-by-side-evaluation of both VNC and post-contrast images could increase the sensitivity of single-phase split bolus DE-CTU.

Methods:
Consecutive patients with haematuria who underwent split bolus DE-CTU on the same dual-source DE-CT scanner were retrospectively enrolled in the study. Intravenous furosemide and oral hydration were employed. Two readers, independently and then jointly in two separate sessions, recorded the location and the longest axial stone diameter on three randomised sets of images: separate VNC and post-contrast images, and side-by-side-reconstructions. True non-contrast (TNC) images served as the standard of reference.

Results:
A total of 83 urinary stones were detected on TNC images. Independent reader side-by-side-evaluation of VNC and post-contrast images yielded higher stone detection sensitivity (76 and 84%, respectively) compared to evaluation of only VNC (71 and 81%, respectively) or post-contrast images (64 and 80%, respectively). The sensitivity of joint reader evaluation of side-by-side-images reached almost 86% and was not significantly different from TNC images (p = 0.77). All stones larger than 3 mm were correctly detected by side-by-side-evaluation. Dose reduction of 55% could be achieved by omitting TNC scans.

Conclusion:
Side-by-side-VNC and post-contrast image evaluation enable detection of clinically significant urolithiasis on single-phase split bolus DE-CTU with significant dose reduction.

Advances in knowledge:
This study shows that single-phase DE-CTU is feasible if VNC imaging is simultaneously utilised with post-contrast images.