bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Development of Gastric Tumours in Drosophila Larvae
Authors: El Shatoury H. H. , Waddington C. H. 
Published: April 2021

ABSTRACT
A sex-linked factor in Drosophila, lethal-no-imaginal-buds (1-nib) produces two main effects: reduction, or even complete absence of the imaginal buds; and excessive proliferation of the epithelium of the stomach, leading to occlusion of the gut and death from starvation. The intensity with which these two effects are expressed varies independently in different stocks. This paper is primarily concerned with the formation of the gastric tumour. The first pair of lymph glands, after their breakdown in the later part of the first instar, usually regenerate only incompletely. With increasing abnormality of the glands, there was an increasing tendency for excessive proliferation, or for cellular degeneration, in the testes, hind-gut primordia, and stomach, in that order. In severely affected larvae, the lymph glands degenerate at the end of the second instar. This is followed by, and is thought to be the cause of, a strong hypertrophy of the gastric epithelium, which leads to the filling up of the gut lumen with cells and anuclear cytoplasmic masses. It is probable that a preliminary stage in the development of this hypertrophy is the proliferation of the cells of the mid-gut imaginal primordia. Similar proliferation and/or hypertrophy occurs in the hind-gut and salivary gland primordia. The cells of all these proliferations eventually undergo degenerative processes involving the deposition of melanin, when they become converted into melanotic ‘tumours’. These are usually anchored to their places of origin, in contrast to the free tumours found in some other Drosophila stocks. Preliminary experiments indicate that the development of the proliferations can be suppressed by the injection of normal lymph glands into early third instar larvae. In individuals from which the cephalic buds are missing, there is no development of the optic glomeruli in the brain. In the stock lethal-malignant (Shatoury, 1955) the lymph glands undergo pathological changes of a different type; they become excessively hypertrophied in the late third instar, and develop into a metastasizing tumour which eventually undergoes various degenerative changes. In this stock also the gastric epithelium begins to exhibit excessive hypertrophy at the same time as the lymph glands become abnormal. A full gastric tumour may develop; in this case the basement cells are involved in addition to the main epithelium. It is suggested that the complex interrelations between the lymph glands, the migratory cells given off from them (oikocytes), and the apparently hormonally controlled proliferative tendencies of tissues such as the gastric epithelium, constitute a novel type of epigenetic system, which may be special to the larvae of holometabolous insects or even of Drosophila alone.
Total Replacement of the Yolk of Chick Embryos
Authors: Grau C. R. , Klein N. W. , Lau T. L. 
Published: April 2021

ABSTRACT
Isolation of the avian embryo from its normal food material is an essential step in a fundamental study of embryonic nutrition. With present methods, however, it has not been possible to grow embryos in culture for much longer than one day. In 1932 Waddington described methods of growing explanted embryos on serum clots. Several years later Spratt (1947, 1952) devised simplified media for embryos cultured on agar with which he studied various aspects of morphogenesis and carbohydrate needs of the young embryo. New (1955) has recently reported another technique for growing explanted embryos which allows development to proceed to about 60 hours, 40 hours of which are in vitro.
Metabolic Characteristics of the Heart-forming Areas of the Early Chick Embryo
Authors: Duffey Lowell M. , Ebert James D. 
Published: April 2021

ABSTRACT
The inhibition of early development by sodium fluoride and antimycin A has been analysed in the early chick embryo cultured in vitro. The relatively specific inhibition of the development of the heart by sodium fluoride, originally reported by Spratt (1950), has been extended to include early streak stages, head process stage, and head fold stage embryos in order to determine the period during development at which the heart-forming tissues become fluoride-sensitive. (a) Fluoride-sensitive areas corresponding to the bilateral prospective heartforming areas arise in the early streak stages. (b) The locations of fluoride-sensitive loci in subsequent stages mirror the sites of highest cardiogenic potency and the areas of highest levels of the cardiac proteins, myosin and actin. In very low concentrations, antimycin A has a striking inhibitory action on the mesoderm of the chick embryo grown in vitro. The brain is free of gross developmental abnormalities in embryos in which all mesodermal derivatives, including heart, have degenerated. The action of antimycin A cannot be prevented by the addition of d-α- tocopherol; however, the effects of this inhibitor can be prevented by doubling the albumen content of the medium. It is suggested, in consonance with recent findings by Nason et al., that a lipid bound to albumin functions in the restoration of activity in the DPN- and succinate-cytochrome c reductases. The results, together with recent information on the specificity of action of the inhibitors, provide a basis for a re-examination of the working hypothesis of Spratt (1950) which holds that brain is dependent primarily on oxidative metabolism and heart on glycolysis. The inhibition of heart by antimycin A reveals a pronounced dependence of this tissue on pathways for DPN oxidation. The combined results of Spratt and the authors, correlated with information on the action of antimycin A and other respiratory poisons, suggest that fundamental differences exist between brain and heart in their respective electron to oxygen transport systems.
Correcting the Genetically Determined Sterility of W
V
W
V Male Mice
Authors: Veneroni Giorgio , Bianchi Angelo 
Published: April 2021

ABSTRACT
In the house-mouse the genotype WvWv is usually sterile. Young male mice of this genotype have been treated with high dosages of f.s.h. (follicle-stimulating hormone) or with f.s.h. associated with testosterone propionate; in some, a unilateral orchidectomy was carried out. Most of the animals thus treated showed a significant recovery in spermatogenesis; some of them, mated to fertile females, had offspring. Untreated WvWv males of our colony have always proved sterile. The sterility-inducing action of the Wv-factor is believed to be accounted for by a deficiency in f.s.h. secretion and/or to a low sensitivity of the germinative tissue to f.s.h. in addition to a deficiency of the primordial sex cells. The treatments did not increase testis size: apparently they stimulated the few derivatives of the primordial sex cells without increasing their number. But this may be sufficient to abolish the sterility of the WvWvmales.
Complete Heterospermic Androgenesis in Silkworms as a Means for Experimental Analysis of the Nucleus-Cytoplasm Problem
Authors: Astaurov B. L. , Ostriakova-Varshaver V. P. 
Published: April 2021

ABSTRACT
In the course of the last 70 years many outstanding biologists have tried to obtain so-called heterospermic merogons, or androgenetic hybrids, developing as a result of interaction between the cytoplasm of one (maternal) and the nuclear material of another (paternal) species. The successful achievement of this experiment was considered the experimentum crucis for the solution of certain fundamental questions of heredity and development pertaining to the so-called nucleus-cytoplasm problem. The most important of these questions was that of the cytoplasmic versus nuclear localization of the physical elements which condition the specific hereditary characters of parental forms and their transmission through successive generations.
Correction of the maternal effect linked to theacmutation, by injury of the egg, in the salamanderPleurodeles waltlii
Authors: Fernandez Maria 
Published: April 2021

ABSTRACTAt the gastrula stage, deep irregular furrows appear on the animal hemisphere in embryos arising from ac/ac females and characterize a maternal effect (Beetschen, 1970). Disturbed morphogenetic movements (epiboly and invagination) frequently elicit exogastrulation or anomalies of later embryonic development. Pricking the animal hemisphere of the uncleaved egg with a micropipette prevents the occurrence of anomalies during gastrulation and neurulation in many embryos. Injection of normal oocyte nuclear sap or of normal egg cytoplasm into mutant female eggs does not improve that result. The partial correction of the maternal effect therefore appears to be consecutive to the injury of the cortical cytoplasm and/or the plasma membrane. Assuming that activation could be deficient, an electric shock was applied to freshly laid fertilized mutant eggs. It did not correct ectodermal anomalies but nevertheless seemed to increase the corrective effect of pricking when both treatments were applied.
Palate Morphogenesis: IV. Effects of serotonin and its antagonists on rotation in embryo culture
Authors: Wee Elizabeth L. , Babiarz Bruce S. , Zimmerman Stephen , Zimmerman Ernest F. 
Published: April 2021

ABSTRACTPrevious studies have localized non-muscle contractile systems in the posterior (region 2) and the anterior (region 3) ends of mouse palates at the time of shelf movement. In order to determine whether these contractile systems function in shelf rotation, effects of pharmacologic agents have been analyzed in embryo culture. First, it was shown that the posterior end of the palate rotates before the anterior end, and its rotation in culture was proportionally greater as development of the embryo progressed. Generally, the posterior end of the palate was more easily inhibited in embryo culture than the anterior end. Serotonin at 10−8 M to 10−5 M was shown to significantly stimulate rotation at the anterior end of the palate after 2 h in embryo culture. The effect on the posterior palate was less pronounced. To investigate further the role of this neurotransmitter on palate shelf rotation, serotonin antagonists were employed. Methysergide (10−4M) inhibited anterior shelf rotation to 12% of control values (P 0·005), while not significantly affecting the posterior end. Ergotamine (10−6 M) significantly inhibited the stimulation induced by 10−5 M serotonin (P 0·025). Cyproheptadine (10−9 M) partially inhibited anterior and posterior shelf rotation in embryo culture. When injected into the pregnant dam, cyproheptadine partially inhibited shelf rotation and fusion. The palate was examined histologically after embryo culture. In the presence of 10−4 M methysergide, the elongated contractile cells in region 3 at the anterior and midpalatal mesenchyme were prevented from rounding. Thus, serotonin may be regulating rotation of the anterior end of the palate by an effect on a cell-mediated process.
Segmental innervation of the chick forelimb following embryonic manipulation
Authors: Bennett M. R. , Lindeman R. , Pettigrew A.G. 
Published: April 2021

ABSTRACTA number of studies have shown that the segmental innervation of some muscles in the developing limb undergoes some modification during the earliest stages of ontogeny. These observations can be interpreted in support of the hypothesis that the motor axons and muscles are matched during this period of development. As a further test of this suggestion we have made a quantitative examination of the motor innervation of the chick forelimb under conditions of controlled abnormal development.Embryos were surgically manipulated at stages before the motor axons invade the limb. The operations were controlled such that forelimbs were induced with segments deleted or reduplicated or simply that a segment of the spinal cord had been deleted. In preparations with abnormal limbs the motor innervation of the muscles present was the same as for those muscles in the normal limb. Where a spinal segment had been deleted the limbs developed normally and their innervation was completed by the remaining brachial segments.These results suggest that any particular matching property of a developing muscle does not develop as a consequence of its position in the limb relative to those segments of the limb proximal to it. Furthermore, that some muscles which are normally innervated by two spinal segments can be completely innervated by one of those spinal segments, in the absence of the other, suggests that any matching between growing axons and developing muscle cells is hierarchical rather than strictly all-or-nothing.
Growth and differentiation of an embryonal carcinoma cell line (C145b)
Authors: Papaioannou V. E. , Evans E. P. , Gardner R.L. , Graham C. F. 
Published: April 2021

ABSTRACTSeveral cell and tumour lines were isolated from a single-embryo-derived teratocarcinoma and their karyotypes and differentiation in adult hosts recorded. The majority of cells contained normal karyotypes by banding. The cells were injected into blastocysts and although they sometimes colonized the yolk sac, they never colonized the embryo. Thus the possession of a normal karyotype is not a sufficient condition for embryo colonization. The loss of growth capacity was investigated by studying differentiation and tumourigenicity in a variety of circumstances. The change in appearance from an EC cell morphology to a big flat cell in culture leads to retardation of growth in adult hosts. When EC cells are injected into a blastocyst, the ability to grow progressively both in culture and in adult hosts is lost.
An autoradiographic analysis of the development of the chick trigeminal ganglion
Authors: D’Amico-Martel Adele , Noden Drew M. 
Published: April 2021

ABSTRACTThe avian trigeminal ganglion, which is embryonically derived from the neural crest and epidermal placodes, consists of two topographically segregated classes of immature neurons, large and small, during the second week of incubation, and two neuronal cell types, dark and light, interspersed throughout the mature ganglion. In order to establish the times of terminal mitosis of trigeminal sensory neurons, embryos were treated with [3H]thymidine during the first week of incubation and their ganglia fixed on embryonic day 11. The embryonically large, distal, placodal-derived neurons are generated between days 2 and 5, while the small, proximal, neural crest-derived neurons are formed mostly between days 4 and 7.By comparing the locations of labeled cells in ganglia treated with isotope but fixed on day 18 of incubation with their 11-day counterparts, we have proved that there are no morphogenetic rearrangements of neurons during the final week of incubation. Thus, no unique relationship exists between the two neuron types in the mature ganglion and the two cell classes in the immature trigeminal. Therefore, both the light and the dark neurons in the mature trigeminal ganglion arise from neural crest as well as placodal primordia.
Estrogen target cells in gonads of the chicken embryo during sexual differentiation
Authors: Gasc Jean-Marie 
Published: April 2021

ABSTRACTEstrogen target cells were searched for in the differentiating gonads of the chicken embryo in order (1) to establish at the cellular level that steroid hormones can play a physiological role in gonadal sexual differentiation, and (2) to localize their sites of action. An autoradiographic technique carried out with frozen sections was employed to demonstrate the presence of binding sites for radiolabelled hormone in the nuclei of the target cells.Target cells for [3H]estradiol are found similarly in gonads of both male and female embryos from (stage 27 of H and H) to 7 days of incubation. Estrogen target cells are observed in the germinal epithelium of the left but not the right gonad, and in the medulla of both the right and left gonads. In the medulla, numerous cells inside the cords are a target for estradiol. The germ cells, difficult to identify unmistakably in the experimental conditions, do not seem to be a target for estrogen hormones. A 100-fold excess of unlabelled estradiol abolishes the nuclear labelling, which is only slightly reduced after a similar excess of unlabelled dihydrotestosterone. It is concluded that the nuclear binding sites have a limited capacity for steroid hormones and are specific for estrogen hormones. The lack of clear and consistent nuclear labelling after [3H]dihydrotestosterone injection confirms the specificity of the [3H]estradiol nuclear labelling. At day 10 of incubation, only the undifferentiated remnant of the germinal epithelium in the left testis still displays labelled cells after [3H]estradiol injection.These observations confirm the determinative role currently ascribed to the estrogen hormones in the cortical differentiation, but they also emphasize that this role extends to the medulla of both gonads. In light of this presence of estrogen receptor sites in the medullary cords as well as in the germinal epithelium, one can assign the estrogen hormones more specific and diversified roles than currently believed. These roles also appear very precocious in the process of gonadal differentiation. Finally, the absence of target cells for estrogen hormones in the germinal epithelium of the right gonad accounts for the lack of cortical differentiation on the right side.
On the role of germ cells in planarian regeneration:I. A karyological investigation
Authors: Gremigni V. , Miceli C. , Puccinelli I. 
Published: April 2021

ABSTRACTSpecimens from a polyploid biotype of Dugesia lugubris s.l. were used to clarify the role and fate of germ cells during planarian regeneration. These specimens provide a useful karyological marker because embryonic and somatic cells (3n = 12) can be easily distinguished from male (2n = 8) and female (6n = 24) germ cells by their chromosome number. We succeed in demonstrating how primordial germ cells participate in blastema formation and take part in rebuilding somatic tissues. This evidence was obtained by cutting each planarian specimen twice at appropriate levels. The first aimed to induce primordial germ cells to migrate to the wound. The second cut was performed after complete regeneration and aimed to obtain a blastema from a cephalic or caudal area devoid of gonads. A karyological analysis of mitotic cells present in each blastema obtained after the second cut provided evidence that cells, originally belonging to the germ lines, are still present in somatic tissues even months after complete regeneration. The role of primordial germ cells in planarian regeneration was finally discussed in relation to the phenomenon of metaplasia or transdifferentiation.
An interaction between dorsal and ventral regions of the marginal zone in early amphibian embryos
Authors: Slack J. M. W. , Forman D. 
Published: April 2021

ABSTRACT
When small explants from early gastrulae of Xenopus laevis are allowed to develop in a buffered salt solution there is a considerable difference between the patterns of differentiation obtained from different dorsoventral levels of the marginal zone. These patterns of differentiation correspond to the fates of the different regions in the course of normal development. They are not altered if several explants of the same type are fused before culture.
If a ventral marginal zone explant from Xenopus is cultured in contact with a piece of dorsal marginal zone from the axolotl, it forms structures more dorsal in character than it would in isolation or in normal development. This behaviour is shown only feebly with other regions of the axolotl gastrula. A piece of dorsal marginal zone from Xenopus is not affected in its development by culture in contact with an explant of ventral marginal zone from the axolotl. The dorsalization of ventral marginal zone explants is shown only if there is a large area of direct contact with the dorsal explant and if the pieces remain in contact for a period of 48 h or more.
It is proposed that this in vitro interaction is the same as the dorsoventral component of action of the ‘organizer’ graft discovered by Spemann and Mangold.
Morphological study of cleft palate development in 5-fluorouracil-treated hamster fetuses
Authors: Shah Ravindra M. , Wong David T. W. 
Published: April 2021

ABSTRACTMorphogenesis of palate was studied in normal and 5-fluorouracil-treated hamster fetuses. The results showed that normal palatal development was completed between days .12 and 13 of gestation. In 5-fluorouracil-assaulted palate the reorientation of shelves from a vertical to horizontal plane was delayed. Crown-rump length, gestational age and fetal weight were reliable predictors of the stages of normal palatal development, whereas the morphological rating system was not. Following 5-fluorouracil treatment, however, crown-rump length, weight and morphological rating were poor indicators of the stage of palatal development.
The site of action of the naked locus (N) in the mouse as determined by dermal-epidermal recombinations
Authors: Raphael Kathryn A. , Pennycuik Pamela R. 
Published: April 2021

ABSTRACTThe dermal-epidermal recombination technique was used to determine the site of action of the naked (N) locus in the skin of the mouse. The skin of athymic (nude) mice was used as a host site for growth of recombined epidermis and dermis from 13- and 14-day N/+ and +/+ embryos. Grafts that contained mutant epidermis lost their hair by 26 days after grafting (at the end of the first hair cycle) and again after 47 days (at the end of the second hair cycle); grafts that contained normal epidermis retained hair throughout the experiment. It was concluded that the N locus acts in the epidermis.
Tissue interactions and the initiation of osteogenesis and chondrogenesis in the neural crest-derived mandibular skeleton of the embryonic mouse as seen in isolated murine tissues and in recombinations of murine and avian tissues
Authors: Hall Brian K. 
Published: April 2021

ABSTRACTMandibular processes from 9- to 13-day-old embryonic mice formed both bone and cartilage when grafted to the chorioallantoic membranes of host embryonic chicks. Isolated ectomesenchyme, taken from 9-day-old embryos did not form bone or cartilage, while older ectomesenchyme formed both. Recombination of the epithelial and ectomesenchymal components confirmed that the presence of the epithelium was a sufficient stimulus for the initiation of both chondro- and osteogenesis. Recombinations between components of mouse and chick mandibular processes showed that 9-day-old mouse ectomesenchyme could respond to chick epithelium but that, although older murine epithelia could initiate osteogenesis from the avian ectomesenchyme, epithelia from 9-day-old embryos could not. These results indicated that an epithelial–ectomesenchymal interaction was responsible for the initiation of both osteo- and chondrogenesis within the mandibular arch of the mouse; that the interaction began at 10 days of gestation; that the ectomesenchyme was capable of responding at 9 days, but that the epithelium did not acquire its ability to act on the ectomesenchyme until 10 days of gestation.
Changes in the surface coat of mesenchymal cells of mouse limb buds after enzymatic cell separation
Authors: Kohnert-Stavenhagen Evamaria , Zimmermann Bernd 
Published: April 2021

ABSTRACTIsolation of cells is nowadays performed by enzymatic means. The influence of such enzymes on the surface coat of mesenchymal and blastemal cells during the dissociation of limb buds from 11-day-old mouse embryos was studied electron microscopically after staining with ruthenium red. EGTA or collagenase failed to bring about cell separation. The surface coat seemed to be unchanged after collagenase treatment. After EGTA an increase in extracellular filaments was observed. The proteases a-chymotrypsin, dispase II, papain, pronase P and trypsin (0·2%, 37 °C, 20 min) succeeded in completely dissociating limb buds. Apart from single granules, there was a detachment of the surface coat from the cells in all cases studied. Hyaluronidase led to only partial separation, but the detachment of the surface coat was almost complete, indicating a GAG-rich surface layer on these cells.