bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Yolk-sacs of Erinaceus europea and Putorius furo
Authors: Morris B. 
Published: April 2021

ABSTRACT
In Erinaceus, the hedgehog, a close relationship between the maternal blood and the embryonic tissues is established soon after implantation by the organization of vascular channels between the trophoblast and adjacent decidua. No comparable organization of vascular channels occurs in the uterine mucosa of Putorius, the ferret. In Putorius the omphaloidean placenta is avascular, and its probable inefficiency as an absorptive organ is reflected in the extremely low concentration of protein in the yolk-sac fluid. Fibrinogen was absent from the yolk-sac fluid in all the stages of pregnancy that were tested. In Erinaceus the omphaloidean placenta, like the allantochorionic placenta, is haemochorial in character. At its optimum development it is highly vascular. The concentration of protein in the yolk-sac fluid of the hedgehog is considerably higher than that in the ferret, but fibrinogen is absent except in very late stages of pregnancy, when the omphaloidean placenta is in an advanced stage of retrogression. It is probable that in these late stages the fibrinogen is of foetal origin. Despite the structural similarity which exists between the early omphaloidean placenta of the hedgehog and that of the rabbit, which is also haemochorial, there is no comparable rapid build up in the concentration of protein in the yolksac fluid of the former such as occurs in that of the latter. The permeability of the membranes must be very different in the two forms. Reichert’s membrane is formed late in development in the hedgehog, and it increases in thickness in very late stages of pregnancy. It appears to be of trophoblastic origin. Reichert’s membrane is absent in the ferret.
A Note on Abnormalities induced in Mouse Embryos by Trypan Blue
Authors: Waddington C. H. , Carter T. C. 
Published: April 2021

ABSTRACT
Females of an inbred CBA strain of mice, kept in the presence of males, were injected with c.c. of 1 per cent, trypan blue solution 7 days after the detection of a copulation plug. In one series of experiments the animals were killed and the embryos recovered 1,2,3, ‘c., days after the injection; in another series the females were allowed to bring their embryos to term. The injected dye soon becomes accumulated in the yolk-sac, and a little later is visible in the region of the placenta. In many -day embryos the rate of development has been slowed down; the closure of the neural tube is abnormal, and the tube itself may show bends and kinks. Sub-epidermal blebs may be found in various regions. The rolling up of the embryo into a right-handed spiral, which normally occurs at about days, is very often affected, the posterior part of the body being deflected to the right. At the same time, the pericardium begins to be very markedly inflated; and it seems probable that the abnormal turning of the embryo is caused by the mechanical impediment presented by the hypertrophied pericardium. There is often a considerable dilation of the embryonic blood-vessels, particularly in the head; and fluids tend to escape from the vessels. There are often haematomata in the tail region. There is a high death-rate of embryos at 12-13 days. Those which survive to term usually show few abnormalities other than shortening or kinking of the tail. There is a marked shortage of females in the surviving young. This is presumably due to a differential death-rate, and since many deaths occur by 12 days, the females must be more sensitive than the males at a still earlier period, well before the time at which sexual differentiation takes place. It is suggested that the main effects of the dye are firstly a general inhibition of development and secondly a more specific effect on the body fluids and circulatory organs.
Axial abnormalities following disturbed growth in Mitomycin C-treated mouse embryos
Authors: Gregg B. C. , Snow M. H. L. 
Published: April 2021

ABSTRACT
Primitive-streak and early-organogenesis-stage mouse embryos were treated with Mitomycin C (MMC) by intraperitoneal injection of pregnant females. Skeletal preparations of newborn pups were made and the axial skeleton examined. The treated animals showed a high incidence of:- (1) changed vertebral numers, (2) malformation of the vertebral column, (3) changed rib numbers and (4) rib abnormalities. These skeletal disturbances tend to be located more posteriorly with later MMC treatment. There is regional variation in the susceptibility of vertebrae to abnormal development. Extra elements may occur in any region of the spinal column and several unique combinations of numbers are reported. The possible origin of these abnormalities and their similarity to some human syndromes is discussed. It is suggested that they may be the consequence of altered growth profiles in interacting tissues during the restorative growth following MMC treatment.
Establishment of pluripotential cell lines from haploid mouse embryos
Authors: Kaufman M. H. , Robertson E. J. , Handyside A. H. , Evans M. J. 
Published: April 2021

ABSTRACTEggs from 129 SvE and (C57BL × CBA)F1 hybrid female mice were activated partheno-genetically following their exposure to a 7 % solution of ethanol in PBS. Only the haploid class which developed a single pronucleus following second polar body extrusion was examined further. These eggs were transferred to suitable recipients and ‘delayed’ blastocysts subsequently recovered. The ‘delayed’ blastocysts were explanted into tissue culture and a total of four haploid-derived pluripotent cell lines established from individual embryos. Chromosome analysis of morulae revealed that over 80% contained only haploid mitoses. However, chromosome analysis of early passage cell lines revealed that all were diploid with a modal number of 40 chromosomes. When transplanted into syngeneic hosts, all lines formed well-differentiated teratocarcinomas. This technique provides a source of homozygous diploid cell lines of parthenogenetic origin.
Evidence that protein ingested by the rat visceral yolk sac yields amino acids for synthesis of embryonic protein
Authors: Freeman Stuart J. , Lloyd John B. 
Published: April 2021

ABSTRACT
[3H]Leucine-labelled haemoglobin was prepared from rat reticulocytes incubated in the presence of [3H]leucine.
Conceptuses from 9-5-day pregnant rats were incubated in vitro for 48 h, with [3H]leucinelabelled haemoglobin present for the final 12, 8, 4, 2 or 0-5 hours. Radioactivity accumulated in visceral yolk sac and in embryonic tissue. When exposure to labelled haemoglobin was for only a short period before harvesting, all the radioactivity found in the embryo and most of that found in the visceral yolk sac was trichloroacetic acid-soluble (i.e. associated with free amino acid rather than with protein). After longer exposures the proportion of radioactivity that was acid-soluble decreased to minimum values of about 20 %.
SDS-polyacrylamide gel electrophoresis of the protein-associated radioactivity in visceral yolk sac and embryo was performed. After exposure to labelled haemoglobin for 1 h only prior to harvesting, the yolk sac contained a single peak of radioactivity coincident in mobility with haemoglobin. The embryo contained no protein-associated radioactivity. After exposure to labelled haemoglobin for 12 h, many protein bands in both yolk sac and embryo were radiolabelled.
Thus a single radiolabelled protein pinocytically captured by the visceral yolk sac can give rise to the presence of many labelled proteins in embryo and visceral yolk sac. These results indicate that the source protein underwent proteolytic digestion and that the amino acids generated were re-utilized for protein synthesis in both embryonic and visceral yolk-sac cells.
In vivo induction of granulopoiesis in visceral yolk-sac cells by foetal hepatic factors
Authors: Anckaert M. A. , Symann M. 
Published: April 2021

ABSTRACT
In order to evaluate the hypothetical activity of foetal hepatic factors on putative yolk-sac haemopoietic stem cells we used the Double Diffusion Chamber (DDC) technique. The DDC were made of a regulator compartment, where foetal hepatic tissue was introduced and a test compartment where visceral yolk-sac cells were cultured. In this system a hepatic signal induced the yolk-sac stem cells to differentiate along the granulocytic pathway but did not stimulate yolk-sac CFUs growth. Contrary to CFUs originating from foetal liver or adult bone marrow, yolk-sac CFUs do not increase numerically in diffusion chamber culture.
Artificial heterokaryons of animal cells from different species
Authors: Harris H. , Watkins J. F. , Ford C. E. , Schoefl G. I. 
Published: April 2021

ABSTRACTA virus, inactivated by ultraviolet light, was used to fuse together cells from different species of vertebrate, and the resulting heterokaryons were examined by autoradiographic and cytological techniques. Heterokaryons could be made with both differentiated and undifferentiated cells: HeLa and Ehrlich ascites cells were studied as examples of undifferentiated cells; rabbit macrophages, rat lymphocytes and hen erythrocytes as examples of differentiated cells. These last three cells were chosen because in them, in varying degrees, the process of differentiation has resulted in suppression of the synthesis of DNA or of both DNA and RNA. This suppression was in all cases found to be reversible: the dormant nuclei could be induced to resume the synthesis of RNA or DNA or both when the differentiated cells were fused with a cell which normally synthesizes RNA and DNA. Observations on heterokaryons in which differentiated cells were fused with HeLa cells and with each other permitted certain general conclusions to be drawn about the regulation of nucleic acid synthesis in the heterokaryon. It was found that if either one of the parent cells normally synthesized RNA, RNA synthesis took place in both types of nuclei in the heterokaryon. If either of the parent cells normally synthesized DNA, DNA synthesis took place in both types of nuclei in the heterokaryon. If neither of the parent cells synthesized DNA, no DNA synthesis took place in the heterokaryon. In all cases where a cell which synthesized a particular nucleic acid was fused with one which did not, the active cell initiated the synthesis of this nucleic acid in the inactive partner. In no case did the inactive cell suppress synthesis in the active partner.The nuclei of heterokaryons in which DNA synthesis took place underwent mitosis, and those nuclei which entered mitosis synchronously usually fused together. This process resulted in the progressive formation of mononucleate hybrid cells, which might thus contain within a single nucleus chromosomal complements derived from different species. These mononucleate hybrid cells were also capable of RNA and DNA synthesis, and many of them in turn underwent mitosis. At metaphase these cells showed, in various combinations, the chromosomal complements of the two parent cells. Mononucleate hybrid cells formed by the fusion of a large number of single cells did not appear to be capable of continued multiplication; but mononucleate cells containing one chromosomal set from each parent cell were still found to be undergoing mitosis many days after cell fusion.
A histochemical analysis of the proteins in the larval fat body of Sarcophaga bullata
Authors: Benson Katherine A. , Benson D. G. 
Published: April 2021

ABSTRACT
A comparison has been made between the basic proteins of the nucleus and the cytoplasm in the larval fat body cell of Sarcophaga bullata. Basic protein was found in four regions of the cell: in the nucleolus, in association with the DNA of the nucleus, as a diffuse reticulum extending throughout the cytoplasm, and as a complement of granules distributed throughout the cytoplasm. Of these four regions only the nucleolar basic protein was apparently unaffected by the blocking reactions of deamination and acetylation when stained with alkaline fast green. The proteins of the other regions were seen to be arginine-rich, but contained a sufficient amount of lysine to be slightly affected by control procedures. The cytoplasmic granular basic protein, lysosomal in nature, and the diffuse basic protein of the cytoplasm, RNA-associated, stained in exactly the same manner as did the nuclear histone with the three techniques used for histone demonstration and with the Sakaguchi reaction. Control procedures had no effect on the intensity of the Sakaguchi reaction in any region of the cell where arginine was demonstrable. It is suggested that the term histone be reserved for DNA-associated basic protein, and that some of the non-specificity of histone staining may be resolved by applying auxiliary methods for the demonstration of acid hydrolases or associated nucleic acids.
The ultrastructure of the cement gland in xenopus laevis
Authors: Perry Margaret M. , Waddington C. H. 
Published: April 2021

ABSTRACT
Alterations which occur during differentiation in the fine structure of the cement gland of the embryo of Xenopus laevis have been investigated. The organ anlage at the late neurula stage is composed of cuboidal cells of comparatively simple cytoplasmic structure. Coincident with the subsequent cellular elongation there is a formation of extensive arrays of functionally interrelated membrane systems, leading to the production of a mucin-like secretory substance. Although there is no direct structural continuity between the membranes of the endoplasmic reticulum and the Golgi apparatus, small vesicles which seem to originate from areas of agranular reticulum appear to transport material synthesized in the endoplasmic reticulum to the Golgi zone. Further elaboration of the product at the site of the Golgi material is suggested by the progressive increase in the quantity of the contents as the cisternae enlarge to form secretory granules.
Other notable features of the differentiating cells are microtubules and cytoplasmic filaments, many of which are oriented in the direction of cellular elongation. In suitably preserved specimens, large numbers of glycogen granules are present. The degenerating gland is characterized by the appearance of large autolytic vacuoles within the cytoplasm. Traces of the membrane systems are present and, in many cells, there remain large numbers of secretory granules.
An electron-microscopical and histochemical study of the oocyte periphery in bombus terrestris during vitellogenesis
Authors: Hopkins C. R. , King P. E. 
Published: April 2021

ABSTRACT
The developing ovarian oocyte of Bombus terrestris has been studied using electron-microscopical, histochemical and autoradiographical techniques. In this publication only the events taking place in the peripheral ooplasm and in the surrounding follicular epithelium are described.
During vitellogenesis three forms of yolk arise. Most of the lipid yolk, together with large numbers of cytoplasmic organelles, is derived from the accompanying trophocyte cells during the earlier phases of yolk synthesis. Later, the larger albuminous yolk spheres which form the major part of the yolk arise at the oocyte periphery as a result of micropinocytotic activity. Yolk precursor materials taken up in this way are probably derived from the haemolymph. Glycogen yolk particles appear in the ooplasm in large numbers during thé later phases of yolk synthesis and arise from groups of small vesicles that have been derived largely from the trophocytes.
Two kinds of follicular epithelial cells occur. All the evidence suggests that the larger, more common form is extremely active during synthesis of albuminous yolk, although its precise role remains unclear. The narrower, less common form of follicular epithelial cell occurs only before albuminous yolk synthesis when its protein secretion is probably transferred to the oocyte.
After yolk synthesis the vitelline membrane is laid down in the intercellular space between the follicular epithelium and the oocyte, both of which contribute towards its formation. Next the chorion is laid down. Although only the earlier stages of its formation have been studied, it is apparent that the chorion is laid down in the intercellular space immediately adjacent to the vitelline membrane, and that it is formed by the follicular epithelium alone.
Formalin perfusion for correlative light- and electron-microscopical studies of the nervous system
Authors: Westrum L. E. , Lund R. D. 
Published: April 2021

ABSTRACT
The formalin perfusion technique of Pease has been shown to be a satisfactory fixation method for both light and electron microscopy of the nervous system of rat and goldfish, so allowing correlative studies to be made on tissue from the same region of one brain.
Immediate post-osmication is not necessary for good ultrastructural preservation and even if it is delayed for 1 week, neuronal structure is adequate for all but detailed cytological work. Unosmicated tissue stained with uranyl acetate and lead citrate showed protein-like structures but not lipids, with membranes appearing as unstained bands. ‘Dark’ glial cells occurred near the surface of the cortex and could not be eliminated by prolonged fixation in situ. ‘ Dark’ neurons were found rarely.
It is suggested that, with this method of fixation, any poor preservation of tissue in direct light- and electron-microscopical correlative studies is due to the subsequent processing rather than the initial fixation. Preliminary results on material stained by a new Golgi-Kopsch modification and by reduced silver methods and subsequently examined with the electron microscope suggest that such damage is not extensive.
Studies on the Sex-Ratio and Related Phenomena
Authors: Parkes A. S. 
Published: April 2021

ABSTRACT(1) The sex-ratio of over 1000 albino mice born in 157 litters worked out at 118 males per 100 females. In the records which I was able to secure of 255 other mice the ratio was 133.8. Both these ratios are above other experimental determinations of the sex-ratio in mice. (2) The seasonal variation in the new breeding records here presented is quite in keeping with work on other mammals, i.e. the ratio is lowest in the height of the breeding season and highest at the extreme end. (3) The data relating to size of litter and sex-ratio show that abnormally small litters have a very low ratio compared with the average, and that abnormally large litters have a sex-ratio rather higher than the average. (4) The sex-ratio is known in some cases to fall with each successive pregnancy, but in the present case the ratio of first births is lower than in subsequent ones. (5) The interpretation of these facts, on the dual basis of the chromosome theory of sex determination and the sexually selective pre-natal mortality which is known to occur, is attempted.
On The Males and an Intersex-Like Specimen of The Parthenogenetic Saw-FlyPristiphora Pallipes, LEP
Authors: Peacock A. D. 
Published: April 2021

ABSTRACTWhilst conducting biological experiments on parthenogenesis in saw-flies during the year 1923, the writer obtained two males and an intersex-like specimen of the species Pristiphora pallipes, Lep., under somewhat peculiar circumstances. As this species appears almost completely thelytokous—the males being exceedingly rare—and as sexual abnormalities in it have never been observed before, and indeed, have only been recorded eight times previously among the Tenthredinidæ, opportunity is here taken of describing and discussing these special appearances. It will be necessary first to dwell upon the experimental conditions as it is not improbable that they may have had a direct bearing upon the results obtained, but in any circumstances the results are of interest in themselves.
Safety of image-guided radiotherapy in definitive radiotherapy for localized prostate cancer: a population-based analysis
Authors: Kuo Yao-Hung , Liang Ji-An , Chen Guan-Heng , Li Chia-Chin , Chien Chun-Ru 
Published: April 2021

Objectives:
Image-guided radiotherapy (IGRT) is a recommended advanced radiation technique that is associated with fewer acute and chronic toxicities. However, one Phase III trial showed worse overall survival in the IGRT arm. The purpose of this observational study is to evaluate the impact of IGRT on overall survival.

Methods:
We used the Taiwan Cancer Registry Database to enroll cT1-4N0M0 prostate cancer patients who received definitive radiotherapy between 2011 and 2015. We used inverse probability treatment weighting (IPW) to construct balanced IGRT and non-IGRT groups. We compared the overall survival of those in the IGRT and non-IGRT groups. Supplementary analyses (SA) were performed with alternative covariates in propensity score (PS) models and PS approaches. The incidence rates of prostate cancer mortality (IPCM), other cancer mortality (IOCM), and cardiovascular mortality (ICVM) were also evaluated.

Results:
There were 360 patients in the IGRT arm and 476 patients in the non-IGRT arm. The median follow-up time was 50 months. The 5-year overall survival was 88% in the IGRT arm and 86% in the non-IGRT arm (adjusted hazard ratio [HR] of death = 0.93; 95% CI, 0.61–1.45; p = 0.77). The SA also showed no significant differences in the overall survival between those in the IGRT and non-IGRT arms. Both groups did not significantly differ in terms of IPCM, IOCM, and ICVM.

Conclusions:
The overall survival of localized prostate cancer patients who underwent IGRT was not inferior to those who did not.

Advances in knowledge:
We demonstrated that the overall survival for prostate cancer patients with IGRT was not worse than those who did not undergo IGRT; this important outcome comparison has not been previously examined in the general population.
Top health research funders’ guidance on selecting journals for funded research
Authors: Shamseer Larissa , Cobey Kelly D. , Page Matthew J. , Brehaut Jamie C. , Grimshaw Jeremy M. , Straus Sharon E. , Stewart Lesley A. , Moher David 
Published: April 2021

Background: Funded health research is being published in journals that many regard as “predatory”, deceptive, and non-credible. We do not currently know whether funders provide guidance on how to select a journal in which to publish funded health research. Methods: We identified the largest 46 philanthropic, public, development assistance, public-private partnership, and multilateral funders of health research by expenditure, globally as well as four public funders from lower-middle income countries, from the list at https://healthresearchfunders.org. One of us identified guidance on disseminating funded research from each funders’ website (August/September 2017), then extracted information about selecting journals, which was verified by another assessor. Discrepancies were resolved by discussion. Results were summarized descriptively. This research used publicly available information; we did not seek verification with funding bodies. Results: The majority (44/50) of sampled funders indicated funding health research. 38 (of 44, 86%) had publicly available information about disseminating funded research, typically called “policies” (29, 76%). Of these 38, 36 (95%) mentioned journal publication for dissemination of which 13 (36.11%) offer variable guidance on selecting a journal, all of which relate to the funder’s open access mandate. Six funders (17%) outlined publisher requirements or features by which to select a journal. One funder linked to a document providing features of journals to look for (e.g. listed in the Directory of Open Access Journals) and to be wary of (e.g., no journal scope statement, uses direct and unsolicited marketing). Conclusions: Few funders provided guidance on how to select a journal in which to publish funded research. Funders have a duty to ensure that the research they fund is discoverable by others. This research is a benchmark for funder guidance on journal selection prior to the January 2021 implementation of Plan S (a global, funder-led initiative to ensure immediate, open access to funded, published research).