bluuebunny/crossref_metadata_2025_split huggingface dataset:
WNT signaling in pre-granulosa cells is required for ovarian folliculogenesis and female fertility
Authors: Habara Okiko , Logan Catriona Y. , Kanai-Azuma Masami , Nusse Roeland , Takase Hinako M. 
Published: April 2021

ABSTRACT
In mammalian ovaries, immature oocytes are reserved in primordial follicles until their activation for potential ovulation. Precise control of primordial follicle activation (PFA) is essential for reproduction, but how this is achieved is unclear. Here, we show that canonical wingless-type MMTV integration site family (WNT) signaling is pivotal for pre-granulosa cell (pre-GC) activation during PFA. We identified several WNT ligands expressed in pre-GCs that act in an autocrine manner. Inhibition of WNT secretion from pre-GCs/GCs by conditional knockout (cKO) of the wntless (Wls) gene led to female infertility. In Wls cKO mice, GC layer thickness was greatly reduced in growing follicles, which resulted in impaired oocyte growth with both an abnormal, sustained nuclear localization of forkhead box O3 (FOXO3) and reduced phosphorylation of ribosomal protein S6 (RPS6). Constitutive stabilization of β-catenin (CTNNB1) in pre-GCs/GCs induced morphological changes of pre-GCs from a squamous into a cuboidal form, though it did not influence oocyte activation. Our results reveal that canonical WNT signaling plays a permissive role in the transition of pre-GCs to GCs, which is an essential step to support oocyte growth.
An immunofluorescent study of the haemoglobinsin metamorphosing Xenopus laevis
Authors: Jurd Richard D. , Maclean Norman 
Published: April 2021

ABSTRACT
It has long been known that in many vertebrates different haemoglobins exist in foetal and adult animals, and that during development the circulating foetal haemoglobin is gradually replaced by haemoglobin of the adult type, (reviewed by Gratzer & Allison, 1960). The phenomenon is well established in the bullfrog, Rana catesbiana (McCutcheon, 1936; Riggs, 1951; Baglioni & Sparks, 1963; Moss & Ingram, 1968a, b). Our studies on haemoglobin from the South African clawed toad, Xenopus laevis, employing column chromatography on carboxymethylcellulose, and polyacrylamide-gel disc electrophoresis, demonstrate a similar situation. Column chromatography reveals two tadpole haemoglobin peaks and three adult peaks, with no peaks common to the tadpole and the adult (Maclean, Brooks & Jurd, 1969; Jurd & Maclean, 1969).
Electrical properties of the slime mould grex
Authors: Garrod D. R. , Palmer J. F. , Wolpert L. 
Published: April 2021

ABSTRACT
An electrophysiological investigation of the migrating grex of the slime mould, Dictyostelium discoideum, has been carried out with two aims in view. It was hoped to obtain information which would be relevant to, first, the formation and regulation of cellular pattern in the grex, and secondly, the problem of grex movement.
Desynchronization of cell divisions in the course of egg cleavage and an attempt at experimental shift of its onset
Authors: Chulitskaia E. V. 
Published: April 2021

ABSTRACT
There is considerable current interest in the study of regularities and modes of regulation of cell cycles in the course of development (Dettlaff, 1964; Graham, Arms & Gurdon, 1966; Chulitskaia, 1967 a). The period of cleavage divisions is a very suitable object for such investigations. It consists of two different periods known as periods of synchronous and asynchronous cell divisions (Syngayewskaya, 1931; Balinsky, 1931; Costello, 1955; Sirakami, 1958; Neyfakh & Rott, 1959; Dan, 1960; Pankova, 1963; Agrell, 1964; Engelberg, 1964; Skoblina, 1965; Chulitskaia, 1967 ó ; Rott & Sheveleva, 1968). Peculiarities of these two periods are known rather well but regularities of the transition from synchronous to asynchronous divisions are still imperfectly understood (Rückert, 1899; Hoff-Jorgensen & Zeuthen, 1952; Agrell & Person, 1956; Neyfakh & Rott, 1959; Neyfakh, 1961; Agrell, 1961, 1962; Pankova, 1963; Brown, 1965; Bachvarova, Davidson, Allfrey & Mirsky, 1966; Timofeeva, Kafiani & Neyfakh, 1967; Chulitskaia, 1967a, b; Rott & Sheveleva, 1968).
Cleavage delay and abnormal morphogenesis in Lymnaea eggs after pulse treatment with azide of successive stages in a cleavage cycle
Authors: Camey Toshie , Geilenkirchen W. L. M. 
Published: April 2021

ABSTRACT
Heat treatments of short duration of successive stages in a cleavage cycle of Lymnaea eggs differentially affect the division cycle and morphogenesis. Effects on the division cycle are most pronounced after a treatment during actual cleavage, at the end of interphase and during prometaphase. Abnormal morphogenesis is only found when a heat shock is applied during metaphase-anaphase stages; after treatment development proceeds up to the blastula stage. Development after the blastula stage, however, may be disturbed, leading to death, exogastrulation or malformations of the embryo.
Stimulation of germ cell proliferation in the planarian Dugesia tigrina (Girard)
Authors: Vowinckel C. 
Published: April 2021

ABSTRACT
Sexual strains of Dugesia tigrina display a seasonal development of sex organs in late summer or autumn and lay cocoons in the suceeding spring. This is followed by a period of asexual reproduction in mid-summer. Such a seasonal alternation of reproductive pathways makes this flatworm an ideal subject of inquiry into the inductive mechanisms controlling reproduction and its ultimate coupling to changes in the environment. Asexual strains of this species reproduce by fission only.
Neurulation in Xenopus laevis. An analysis and model based upon light and electron microscopy
Authors: Schroeder Thomas E. 
Published: April 2021

ABSTRACT
It is a matter of general knowledge that neurulation, as it occurs in most chordate embryos, proceeds by longitudinal in-folding of the neural plate. Lovtrup (1965) ably described such morphogenetic movements as they occur in several neurulating amphibians. The mechanical causes of these movements are not clearly understood, however. In his review of the prominent theories of neurulation, Curtis (1967) points to their various inadequacies and concludes that ‘possibly the solution of this problem is to search for contractile movements in the cells involved in neurulation’ (p. 310).
Experiments on β-mercaptoethanol as an inhibitor of neurulation movements in amphibian larvae
Authors: Jacobson Carl-Olof 
Published: April 2021

ABSTRACT
The morphogenetic movements of the ectoderm during neurulation include: (1) the movements taking place within the neural plate, which becomes longer and more concentrated in a medio-lateral direction (Jacobson, 1962); and (2) those found in the lateral epidermis layer which, in an epibolic way, moves in a dorsal direction, thus exerting a pushing effect on the lateral edges of the neural plate (Lewis, 1947). The former is, to a great extent, realized by a change of form of the neuroepithelium cells, from cuboidal in early neurulae to the high columnar cells observed during later phases of neural-tube closure. In the epidermis, on the other hand, the case is the reverse. The dorsal spreading of the layer is made possible by a flattening of the cells.
L’action de l’actinomycine D sur le pouvoir inducteur du nœud de Hensen et la compétence neurogène de l’ectoblaste de poulet
Authors: Gallera Par J. 
Published: April 2021

ABSTRACT
Chez les Bactéries, l’actinomycine D se fixe sur l’ADN et empêche la formation de l’ARN messager, ce qui se traduit presque instantanément (après quelques minutes au maximum) par le blocage de la synthèse des protéines spécifiques. L’action de l’actinomycine sur les cellules animales est plus complexe. Employée à doses très faibles, elle semble affecter surtout la formation de l’ARN messager, mais elle peut aussi agir directement sur les composants cytoplasmiques. Administrée à une concentration plus forte, elle se révèle nettement toxique. D’autre part, le cytoplasme des cellules animales contient toujours un stock important de divers ARN messagers plus ou moins stables dont l’action ne peut se manifester qu’au moment ou les autres composants cytoplasmiques atteignent un état déterminé de maturation. Par conséquent, l’arrêt de la production de l’ARN messager ne se répercute sur la synthèse des protéines qu’après un délai plus ou moins long. Chez les Oursins, l’actinomycine naltère pas le développement embryonnaire jusqu’au stade de la blastula (Giudice, Mutolo & Donatuti, 1968). Chez les Urodèles (Brachet & Denis, 1963) et chez la Truite (Hagenmaier, 1969), le développement se poursuit normalement jusquau début de la gastrulation. Selon Flickinger (1963), Heilporn-Pohl (1964), Leani Collini & Ranzi (1967), l’ARN spécifique de chaque tissu embryonnaire serait synthétisé, chez les Anoures et les Oiseaux, juste avant sa différenciation. Ajoutons encore quil est souvent impossible de préciser la nature de l’ARN dont la synthèse a été inhibée par l’actinomycine (Denis, 1966). 11 est d’ailleurs probable que les anomalies graves résultent d’une action toxique de cet antibiotique (Harris, 1968). Toutefois, l’emploi d’un matériel, qui se prête particulièrement bien à létude de la synthèse massive des protéines spécifiques, a permis à Soriano (1968) de démontrer que l’epithélium œsophagien de Souris cultivé in vitro sur un milieu additionné d’actinomycine D à raison de 0,05 μg/ml empêche entièrement la kératinisation, sans que cet épithélium, retransplanté sur le milieu normal après 24 h, montre le moindre signe de dégénérescence et que lincorporation de leucine tritiée soit diminuée.
Recent findings on oogenesis of Drosophila melanogaster: II. Further evidence on the origin of yolk platelets
Authors: Giorgi F. , Jacob J. 
Published: April 2021

ABSTRACT
Vitellogenic ovaries from Drosophila melanogaster flies have been exposed, either in in vivo or in vitro conditions, to various extracellular tracers in an attempt to determine the possible route of entry of the yolk precursors.
Ruthenium red and lanthanum nitrate have been shown to gain access to the oocyte surface by initially passing through the intercellular spaces of the follicle layer. Both these tracers, however, never attain an intracellular location within any of the cells forming the ovarian chamber.
Colloidal Thorotrast when injected into adult females has never been detected within any of the ovarian chambers examined, irrespective of their stage.
Vitellogenic oocytes exposed to peroxidase in in vivo conditions exhibit the oolemma and all the structural elements present in the cortical ooplasm well labelled within a very short time after the injection. Moreover, with gradually increasing exposure times to peroxidase, the labelled yolk platelets increase progressively in number. At each time interval after the injection, the label over the yolk platelets remains restricted to the superficial layer and never gets into the associated body.
The pattern of tritiated lysine incorporation into vitellogenic oocytes has been studied over a period of 20 h. A few hours after injection of the radioactive tracer, the silver grains located over the ooplasm appear distributed at random. A predominant labelling of the yolk platelets as compared to the rest of the ooplasm, becomes evident only with a 6 h delay since the time of injection.
When analysed by electrophoresis and isolectrofocusing, the vitellogenic ovary is seen to exhibit a number of protein bands which are common to those of other tissues as, for instance, haemolymph and fat body.
The evidence obtained in the present study is discussed in relation to the hypothesis of an extraovarian origin of the yolk precursors and their sequestration into forming yolk platelets.
Le matériel extracellulaire au cours du développement du chondrocrâne des amphibiens: Mise en place et constitution
Authors: Corsin Jacqueline 
Published: April 2021

ABSTRACTChanges in the extracellular matrix of the cranial cartilages of amphibiansDuring the differentiation of cranial cartilages the composition of perichordal and perineural extracellular matrix changes: at first only collagen and hyaluronic acid can be detected, later chondroitin-sulphates 4 and 6 appear and their concentrations progressively increase while the concentration of hyaluronic acid is decreasing.The possible effects of these substances not only on the chondrogenetic cells but also between themselves are discussed.
Importance des associations de tissus du membre dans le développement des membres surnuméraires induits par déviation de nerf chez le Triton Pleurodeles waltlii Michah
Authors: Lheureux Emile 
Published: April 2021

ABSTRACT
Importance of limb tissue associations in the development of nerve-induced supernumerary limbs in the newt Pleurodeles waltlii Michah.
Brachial nerve tip deviation has been carried out at various points in the upper arm and close to the limb. Some associations of cutaneous or muscular tissue from two opposite sides - dorsal and ventral or anterior and posterior - of the upper arm were made at these points. Various degrees of development of the nerve-induced supernumerary limbs were observed. When a nerve deviation was not followed by grafting of tissue from the opposite side, the supernumerary limbs did not develop or were strongly hypomorphic. A normal limb development can occur when tissues from the opposite side are associated with the ones located at the nerve tip. Such associations allow a harmonious nerve-induced supernumerary limb to develop and consequently allow all transverse axes to be established. Orientation of nerve-induced supernumerary limbs is determined by the orientation of the tissues in the area of nerve deviation.
In terms of positional information, since an absence of contact between tissues from two opposite sides results in a lack of normal development, we can conclude that positional values located on either side of, the centre of, at least, one transverse axis should be in contact to allow limb development, i.e. a regenerated limb or nerve-induced supernumerary limbs or supernumerary limbs. It appears that contact between such values along any transverse axis, under sufficient nervous stimulation may give rise to a supernumerary limb.
In vitrodevelopment of haploid mouse embryos produced by bisection of one-cell fertilized eggs
Authors: Tarkowski Andrzej K. 
Published: April 2021

ABSTRACTF1(CBA × C57BL/10) mouse eggs originating from spontaneous or induced ovulation and fertilized by CBA-T6T6 or PO spermatozoa were bisected with a glass needle into halves each containing a pronucleus. This technique offers a unique opportunity of producing both andro-genetic and gynogenetic haploid embryos from one egg.Out of 600 operated eggs, in 406 (67·7%) both halves survived. During 96 h of culture in vitro the fragments were inspected once daily and finally examined in air-dried preparations. Eighty-seven per cent of halves underwent first cleavage but their further development was to a large extent affected by extrinsic factors connected with experimental procedure (mainly by suboptimal and variable culture conditions) and by the origin of eggs (those from spontaneous ovulation being superior). For this reason developmental capabilities of egg halves were assessed in a selected group of pairs in which at least one partner reached the stage of four or more blastomeres. The observed ratio between pairs with both or only one sister embryo developing successfully suggests that androgenetic embryos carrying Y rather than X chromosome can cleave twice but do not survive beyond 4-cell stage. None of the metaphase plates from older embryos contained a Y chromosome. These observations imply that the X chromosome is genetically active during early cleavage and that a full haploid set is required for preimplantation development to be completed.Formation of blastocysts varied from batch to batch, with an average of 12-8% and maximal incidence of 29·5%. In 34 pairs both fragments developed beyond the 4-cell stage but in only one case did both form blastocysts. Haploid blastocysts were composed of 27 cells on average which was about a half of the number of cells in control diploid zona-free whole eggs. Ten out of 51 embryos with metaphase plates proved to be haploid/diploid mosaics.
In vitrodevelopment of palatal tissues from embryonic mice: II. Tissue isolation and recombination studies
Authors: Tyler Mary S. , Koch William E. 
Published: April 2021

ABSTRACTThe epithelial and mesenchymal tissues of the secondary palate from 12-, 13-, and 14-day embryonic mice were enzymatically separated and cultured in isolation and in homochronic and heterochronic recombinations. In both homochronic and heterochronic recombinations, epithelial differentiation was similar to that in vivo. In heterochronic recombinations, epithelium differentiated according to a schedule appropriate for the age of the epithelium rather than for the age of the mesenchyme, suggesting that differentiation of palatal epithelium is temporally ‘determined’ as early as 12 days of gestation. Palatal epithelium cultured in isolation was capable of limited differentiation. Potential for differentiation therefore exists within the isolated palatal epithelium at an early stage of palatal development, and epithelial-mesenchymal interactions are required during palatal development to support full epithelial differentiation.
Blood formation in a clonal cell line of mouse teratocarcinoma
Authors: Cudennec Claude A. , Nicolas Jean-Francois 
Published: April 2021

ABSTRACT
Pluripotent cells of a teratocarcinoma clonal line differentiate into various tissues when they are cultivated in submerged cultures. We describe here the formation of endodermal vesicles and blood islands in organotypic cultures of such cells. These are the first macroscopically visible tissues to appear in organ culture and they give rise to megalocytes, the ultimate stage of blood cell evolution in the normal mouse embryo yolk-sac. As in the normal embryo yolk-sac, the formation of haemoglobin-containing cells stops after a while, but it is not replaced by adult haemopoiesis in culture.
Studies on the development of F1 embryos from inter-strain crosses involving DDK mice
Authors: Wakasugi Noboru , Morita Mitsuyo 
Published: April 2021

ABSTRACT
The development of the early mouse embryos was investigated from 36 to 84 h after the presumed time of fertilization. The mean number of cells constituting the embryo from the intra-strain crosses of three strains at 84 h of development was as follows: DDK, 22·7; BS, 43-1 and ITES, 62·0. A significant difference was observed in the cleavage rate of the embryo between DDK and the other two strains.
The F1 embryos from the crosses of BS females × DDK males and ITES females x DDK males showed almost the same progress of development as BS and ITES embryos, respectively. Therefore, it is concluded that the early development of the F1 embryos is regulated mainly by the factors from the mother.
The morulae from the semi-sterile cross, DDK females x BS males, showed conspicuously small cell numbers as compared with their litter-mates that developed to the blastocyst stage. It is inferred that the discrimination is already made during cleavage between the fortunate survivors and the lethal embryos due to the incompatibility between the cytoplasmic factor of DDK eggs and alien spermatozoa.
Quantitative aspects of proliferation in the nasal epithelium of the rhesus monkey embryo
Authors: Wilson Doris B. , Hendrickx Andrew G. 
Published: April 2021

ABSTRACT
Proliferation was studied in the nasal epithelium of rhesus monkey embryos ranging in age from 26 through 41 days of gestation (stages 13 – 20). Labeling indices were tabulated 1 h after an intrachorionic injection with [3H]thymidine, and the distribution of labeled cells was determined at intervals ranging from 1 h to 11 h after injection. The labeling index showed a chronological decrease from 69·4% in the nasal placode at stage 13 to 31·6% in the nasal pit at stage 20. The vomeronasal epithelium was distinctive in that the basal cells lost their ability to incorporate [3H]thymidine as early as stage 18. In the remainder of the nasal epithelium, mitotic figures were initially confined to apical regions but later occurred in basal regions as the embryonic pattern of proliferation became converted to the adult type.
An ultrastructural and biochemical study of high density primary cultures of embryonic chick chondrocytes
Authors: Oakes B. W. , Handley C. J. , Lisner F. , Lowther D. A. 
Published: April 2021

ABSTRACTPrimary cultures of embryonic chick chondrocytes inoculated at high densities (5 – 6 × 106 cells/25 cm2 Falcon Flask) with adequate pH control, grow rapidly and multilayer with 5 – 8 cell layers forming a uniform thick approximately 50 – 80 μ m dense cartilage matrix. Cultures inoculated at lower densities tended to form nodular aggregates of chondrocytes secreting a typical cartilage matrix with the internodular areas occupied by elongated, vacuolated, fibroblast-like cells secreting little matrix. Ultrastructurally, using ruthenium red during fixation, early cultures revealed rounded cells surrounded by a collagen matrix of small diameter (150 nm) collagen fibres to which were irregularly attached electron-dense granules approximately 20 nm diameter. Fine filaments of 1 nm diameter linked the electrondense granules to one another, to collagen fibres and to the cell membrane. In older cultures larger cells were observed with ultrastructural features similar to hypertrophic chondrocytes seen in vivo. Electron-dense material composed of fine needle-like structures was observed in the matrix associated with these cells. These observations were interpreted as early calcification occurring in vitro in relation to hypertrophic cells.The molecular weight of the proteoglycans and the spectrum of glycosaminoglycans synthesized were similar to that of normal embryonic chick cartilage, demonstrating maintenance of chondrocyte differentiation in this system.This study demonstrates that it is possible by using high density cultures with adequate nutrient media and pH control to maintain chondrocytes in a differentiated state using the criteria of ultrastructural morphology and specificity of the matrix they synthesize.
Mouse teratomas and embryoid bodies: their induction and differentiation
Authors: Iles S. A. 
Published: April 2021

ABSTRACT
Teratomas were induced by the transfer of mouse blastocysts (C3H and 129/J strains) and egg-cylinders (C3H) to extra-uterine sites. C3H and 129/J blastocysts cultured in vitro for 4 or 5 days could also form teratomas in extra-uterine sites.
Four transplantable teratomas, or teratocarcinomas, were derived from C3H embryos; embryoid bodies were derived from each line. The differentiative capacity of a teratocarcinoma was shown to be similar whether it was maintained as a solid tumour or as embryoid bodies.
Retino-tectal projections from half-ventral and half-dorsal eye rudiments in Xenopus
Authors: Feldman Joan D. 
Published: April 2021

ABSTRACT
When the ventral half of a developing eye in Xenopus larvae was removed at stage 32, the remaining fragment rounded up and developed into an eye which looked macroscopically normal by mid-larval stages. Eyes from half-dorsal rudiments were usually small, had more than one ventral fissure, and showed abnormal pupils. The contralateral retinotectal projection was always found to be normally ordered when mapped in later tadpole stages, or, just after metamorphosis. No mirror-image duplicated maps were seen, as was found pre-viously in eyes deriving from half-nasal and half-temporal rudiments.
It is concluded that the ‘rule of distal transformation’ does not apply to eyes which are generated from embryonic rudiments.