bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effect of transection of the duck blastoderm on the orientation of the embryo
Authors: Rogulska Teresa 
Published: April 2021

ABSTRACT
Von Baer (1828) formulated a rule according to which the cephalo-caudal axis is perpendicular to the long axis of the shell, and the head of the embryo is directed forwards when the egg is placed with the blunt end to the left. This law has been checked in several species of bird: hen, duck, pigeon, goose, turkey (see Clavert, 1960, for references) and quail (Fargeix, 1963, 1964). Embryos obeying von Baer’s rule were found to constitute the most numerous class, but considerable interspecific as well as intraspecific differences were observed.
Cytonucleoproteins in cleaving eggs of Xenopus lœvis
Authors: Arms K. 
Published: April 2021

ABSTRACT
The cytoplasm of unfertilized eggs of Xenopus laevis induces DNA synthesis in a high proportion of adult and embryonic nuclei introduced into it (Graham, Arms & Gurdon, 1966). This induction of DNA synthesis is not due merely to the fact that the egg cytoplasm supplies precursors of DNA synthesis which might be absent from the nuclei, since adult liver nuclei, at least, of those nuclei which are induced to synthesize DNA after their injection into eggs, do not do so if incubated in vitro with DNA precursors (Arms, 1968). One of the ways in which the cytoplasm of unfertilized eggs might induce DNA synthesis is by supplying other molecules, such as various enzymes, to the introduced nuclei.
The effects of embryonic pars distalis grafts and albumen on the growth of chick embryos
Authors: Betz T. W. 
Published: April 2021

ABSTRACT
Normal chick embryos swallow and utilize the albumen in the egg between the 11th and 15th day of incubation (Witschi, 1949). They use approximately two-thirds of the yolk by the end of incubation (Romanoff & Romanoff, 1949). Thus the embryo has access to 4 g of protein in the albumen and 3 g of protein in the yolk (Romanoff & Romanoff, 1949). Embryos which have been hypo-physectomized by partial decapitation, which is the only practical way of hypophysectomizing chick embryos (Betz, 1965 a, see also the reviews of Benoit (1962) and of Hinni & Watterson (1963), do not develop an upper beak and do not swallow much of the albumen since most of it remains in the egg (Witschi, 1959; Betz, 1965b).
Morphogenetic analysis of the effects of juvenile hormone analogues and other morphogenetically active substances on embryos of Schistocerca gregaria (Forskål)
Authors: Novák Vladimír J. A. 
Published: April 2021

ABSTRACT
One of the basic assumptions of the author’s gradient-factor theory of insect morphogenesis is that the effects of the hypothetical gradient-factor on tissue growth can be reproduced by the juvenile hormone, not only during postembryonic development, but also in the course of embryogenesis (Novák, 1951 a, b, 1956, 1966). This concept was originally based on the more or less indirect evidence supplied by the findings of Pflugfelder (1947) in Dixippus morosus and by those of Novak (1951 b) in Oncopehus fasciatus.
Le mécanisme d’ entrée des cellules germinales primordiales dans le réseau vasculaire, chez l’ embryon de Poulet
Authors: Dubois Regis 
Published: April 2021

ABSTRACT
La lignée germinale des Oiseaux fait l’ objet, depuis une quinzaine d’ années, de travaux expérimentaux basés sur la technique des cultures in vitro. Ces recherches ont apporté des résultats décisifs concernant les questions du transport des cellules germinales primordiales (CGP) par la voie sanguine (technique des parabioses circulatoires in vitro, Wolff & Simon, 1957) et de la colonisation des ébauches gonadiques (technique des associations in vitro, Dubois, 1964, 1968).
Magnitude and pattern of compensatory growth in rats after cold exposure
Authors: Lee Marjorie M. C. , Chu P. C. , Chan H. C. 
Published: April 2021

ABSTRACT
It is a common observation that normal growth is affected or suppressed in young individuals by environmental adversities and physical disturbances. On the other hand, when health or favorable conditions are restored, the tempo of growth promptly accelerates as if the individual is trying to make up for the growth debt incurred. Tanner has referred to this increased growth rate after diseases or starvation as compensatory or ‘catch-up’ growth, a topic on which he has written eloquently and fully in a number of articles (1963a, b). He considers this compensatory growth as a ‘self-stabilizing’ or ‘target-seeking’ phenomenon in the regulatory control of growth.
Changes in mitotic rate during compensatory renal growth in Xenopus laevis tadpoles after unilateral pronephrectomy
Authors: Chopra D. P. , Simnett J. D. 
Published: April 2021

ABSTRACT
In many organs partial extirpation is followed by compensatory hypertrophy in the residual tissue which is generally brought about by a temporary increase in the rate of cell division. After unilateral nephrectomy in the rat, cell proliferation in the contralateral kidney starts after a latent period of 24 h and reaches its maximum rate about 24 h later (Goss & Rankin, 1960). Similar results were obtained in immature metamorphosed Xenopus laevis after partial extirpation of liver and kidney. In this case the increased cell proliferation starts at 3 days and reaches a maximum 6 days after the operation (Chopra, unpublished results). Although the timing of the response may thus vary according to the experimental conditions the pattern of a latent period followed by a rapid increase in the mitotic rate seems to be a general phenomenon.
Effects of trypan blue and Niagara blue 2 B on the in vitro absorption of ions by the rat visceral yolk sac
Authors: Kernis Marten M. , Johnson E. Marshall 
Published: April 2021

ABSTRACT
Prior to 1927, when Brunschwig proposed that the rat visceral yolk sac is functionally a placenta, it was customary to consider the chorio-allantoic placenta as the primary organ for bringing nourishment to and taking waste from the developing embryo and growing fetus. Eight years later, Everett (1935) predicted that the visceral yolk sac is functionally at least as important as the chorio-allantoic placenta, while Noer & Mossman (1947) suggested that the yolk sac functions differently from the placenta and is therefore complementary in its role. More recently, Halliday (1955) indicated that the proximal yolk sac of the rat is capable of absorbing antibodies by day 17 of gestation. This was confirmed by Brambell & Halliday (1956), who were able to demonstrate that the vitelline epithelium and its underlying vascular system are partly responsible for antibodies penetrating into the embryo. Padykula, Deren & Wilson (1966) noted that the rat yolk sac has the ability to absorb vitamin B12 and that this ability is stimulated by the presence of intrinsic factor. The yolk sac has also been shown to be capable of actively transporting certain amino acids (Deren, Padykula & Wilson, 1966) and is able to accumulate ferritin by means of pinocytosis (Lambson, 1966).
The programming of differentiation and its control by juvenile hormone in saturniids
Authors: Willis Judith H. 
Published: April 2021

ABSTRACT
Although considerable progress has been made with the chemistry of juvenile hormone (Dahm, Roeller & Trost, 1968), studies on its mechanism of action in immature insects are still in a preliminary stage. Much of the recent work has been interpreted as showing an effect of juvenile hormone on the morphogenetic program through which an insect passes in the course of its ontogeny (Williams, 1961). It is the purpose of this paper to describe three studies which illustrate the complex nature of this developmental program in saturniid moths.
Threshold phenomena versus cell heredity in the manifestation of sex-linked genes in mammals
Authors: Grüneberg Hans 
Published: April 2021

ABSTRACT
The mode of action of sex-linked genes in mammals has been the subject of much discussion in recent years. This has centred round the concept that in the mammalian female, either the maternal or the paternal X-chromosome is randomly and irreversibly inactivated during development, with the result that in the female, as in the male, one X-chromosome only is active in a given cell (Lyon, 1966, and earlier papers). The Lyon Hypothesis (L.H.) is based, in part, on the mottled or striped phenotypes of heterozygotes for certain sexlinked genes affecting the coat of the mouse and other mammals: these phenotypes are regarded as a mixture of clones descended from cells in which either one or the other X-chromosome has been inactivated. As Baker (1967) rightly insists, the interpretation of a pattern as clonal must be based on known cell lineages, as without such a basis one simply postulates what should be put to the test.
Aspects of the tabby—crinkled—downless syndrome : I.The development of tabby teeth
Authors: Sofaer J. A. 
Published: April 2021

ABSTRACT
The sex-linked gene tabby, Ta (Falconer, 1953), and two autosomal mimics of tabby, crinkled (cr, linkage group XIV) (Falconer, Fraser & King, 1951; King, 1956) and downless (dl, linkage group IV) (Mouse News Letter, 1960,1966) each produce a similar mutant syndrome involving the coat and dentition of the mouse. Studies on the coats of tabby and crinkled mice point to a timed gene effect causing suppression of formation of new hair follicles between and 17 days of gestation and again from birth onwards, with a reduction in the rate of growth of the follicles that do form (Falconer et al. 1951). Associated with this is a reduction in hair calibre and a lack of differentiation of the coat into hair types (Grüneberg, 1966 b). A model to explain the timed action of the tabby gene has been proposed by Dun (1959).
Gut and nerve-cord interaction in sabellid regeneration
Authors: Fitzharris Timothy P. , Lesh Georgia E. 
Published: April 2021

ABSTRACT
Studies of annelid regeneration have considered interactions which may exist between the gut and nerve-cord. Although the influence of the gut has often been assigned a secondary role (Kroeber, 1900; Morgan, 1902; Hunt, 1919; Faulkner, 1932; Sayles, 1932), the necessity for its presence has been demonstrated in certain instances (Okada, 1938). Attention therefore has been primarily directed to the nerve-cord, particularly the trophic influences of this structure at the wound site (Goldfarb, 1914; Bailey, 1930 & 1939; Avel, 1932; Crowell, 1937), and its influence posterior to the wound area, presumably hormonal in nature (Kropp, 1933; Clark, R. B. & Clark, M. E., 1959; Clark, R. B. & Bonney, 1960; Clark, M. E. & Clark, R. B., 1962; Scully, 1964; Golding, 1967a-c). Regardless of the organism or the approach used, previous investigators have pointed to one persistent problem: the independence or interdependence of these two organ systems in the structuring of the regenerate bud. Specifically, what does the gut contribute to the regenerate bud and in what manner, if any, does the nerve-cord direct the formation of the bud? Because of the lack of histological data, plus conflicting views on the exact ordering of these regenerating organ systems, this study will attempt to resolve the problem of tissue interaction involved in normal regeneration.
The effect of tetracyclin on the processes of calcification of the otoliths in the developing chick embryo
Authors: Balsamo Giuseppe , de Vincentiis Mario , Marmo Francesco 
Published: April 2021

ABSTRACT
It is known that tetracyclin is fixed in calcified tissues and that it can have an inhibitory action on calcification processes under certain conditions (Saxén, 1966). The mechanism by which tetracyclin is bound to the calcified structures is not clearly understood. Some workers believe that there is simple chelation between the antibiotic and calcium (Albert, 1953); others believe that the fixation of tetracyclin is mediated by more complex mechanisms (Sternberg, 1966; Saxén, 1966). The latter hypothesis is based on the observation of the presence of both a stable complex of tetracyclin-Ca and an unstable form from which either the calcium or the tetracyclin can undergo rapid changes.
Embryonic development of the heart
Authors: Manasek Francis J. 
Published: April 2021

ABSTRACT
The mature heart may be thought of as consisting of three layers, endocardium, myocardium, and an outer investing tissue called the epicardium. During early formation of the tubular heart of chick embryos, at about the 8-somite stage, two tissue layers become clearly discernible with the light microscope: the endocardium and the developing myocardial wall. The outer epicardial layer does not appear until later in development.
Epithelial and mesenchymal cell interactions with extracellular matrix material in vitro
Authors: Slavkin H. C. , Bringas P. , Cameron J. , Lebaron R. , Bavetta L. A. 
Published: April 2021

ABSTRACT
Epidermal organogenesis (thyroid gland, salivary gland, feather, hair, skin, thymus gland, tooth, etc.) generally follows a basic rule; epithelium exhibits well-documented interdependence with adjacent mesenchyme for a specific path of development (Grobstein, 1967, for review). Koch (1967) demonstrated in rodent embryos that isolates of incisor epithelial and mesenchymal tissue, separated by a millipore filter, continued to develop. When homotypic tissues were placed in juxtaposition to the filter, no evidence of continued differentiation was observed.
Experimental studies on morphogenetic factors localized in the first and the second polar lobe of Dentalium eggs
Authors: Geilenkirchen W. L. M. , Verdonk N. H. , Timmermans L. P. M. 
Published: April 2021

ABSTRACT
During the development of several annelids and molluscs, a lobe of protoplasm is observed to protrude from the vegetal pole of the egg during the first cleavages. Removal of this polar lobe causes characteristic defects in the developing larvae as has been observed in the scaphopod, Dentalium (Wilson, 1904; Verdonk,1968), the annelid Sabellaria (Hatt,1932; Novikoff,1938), the gastropod Jlyanassa obsoleta (Crampton, 1896; Clement, 1952) and the lamellibranch, Mytilus edulis (Rattenbury & Berg, 1954).
Analyse autoradiographique de la localisation des différentes ébauches présomptives dans la ligne primitive de l’embryon de Poulet
Authors: Nicolet Par G. 
Published: April 2021

ABSTRACT
Le problème de la localisation des ébauches présomptives chez les Oiseaux est actuellement l’un des thèmes les plus controversés de la littérature embryologique (Grâper, 1929; Wetzel, 1929, 1936; Pasteels, 1937; Rudnick, 1944, 1948; Spratt, 1955). Une nouvelle analyse de ce problème s’impose, encore faut-il que la méthode employée soit réellement capable d’obvier aux désavantages des techniques de marquage usuelles. En effet, en particulier chez les Oiseaux, ni la technique de coloration locale au bleu de Nil, ni l’apposition de fines particules ne donne la garantie formelle que la marque se rapporte strictement au même ensemble de cellules du début à la fin des expériences. Nous croyons que l’emploi de la thymidine tritiée comme marqueur nucléaire peut surmonter cet obstacle. Ce radioisotope s’incorpore spécifiquement dans l’ADN et ne se transmet qu’aux cellules-filles issues de cellules marquées. Cette technique a déjà été employée à plusieurs reprises chez le Poulet. Weston (1963) a étudié la migration des éléments de la crête neurale, Rosenquist & De Haan (1966) ainsi que Orts-Llorca & Collado (1967) ont analysé la morphogénèse du cœur. Modak (1966) s’est consacré au problème de la régénération de l’endoblaste, alors que Rosenquist (1966) et Nicolet (1965, 1967) ont précisé la destination des cellules provenant de diverses régions du blastoderme.
Les caractères de la segmentation et la détermination de la polarité dorsoventrale dans le développement de quelques Spiralia
Authors: Guerrier Pierre 
Published: April 2021

ABSTRACT
Des travaux antérieurs m’ont permis de montrer que les déterminations axiales des œufs de Parascaris equorum, de Limax maximus et de Sabellaria alveolata se fixent selon un mode partiellement épigénétique au cours des premières divisions (Guerrier, 1967; 1968; 1970a, b). Le mode de segmentation inégal, particulier à l’œuf de certains Lamellibranches, permet de se demander si celui-ci n’est pas le siège d’un processus original, relevant éventuellement d’une structuration dorsale préformée au sein de l’œuf indivis. Cette hypothèse, retenue par Tyler (1930) après des études portant sur Cumingia tellinoïdes est réfutée par Pease (1940) qui, sur le même matériel, examine les effets d’une stratification des éléments endoplasmiques. Nous avons choisi d’étudier deux espèces dont les œufs, remarquablement transparents, permettent de suivre avec une très grande précision les mouvements des constituants cellulaires au cours de la segmentation. L’emploi de la compression et de la centrifugation a permis de déplacer ces constituants selon des modalités diverses et d’examiner les conséquences de ces interventions sur la morphogenèse. Nos observations nous conduisent à conclure que la fixation des principales potentialités et, en particulier, de la symétrie dorsoventrale, répond ici à un mécanisme épigénétique qui présente de nombreuses analogies avec celui que nous avons rencontré chez d’autres Spiralia.
Steroid control of the normal development of glutamine synthetase in the embryonic chick retina
Authors: Piddington R. 
Published: April 2021

ABSTRACT
Glutamine synthetase (GS) activity in the neural retina of the chick embryo is inducible with corticosteroids (Moscona & Piddington, 1966; Piddington, 1967; Moscona, Saenz & Moscona, 1967; Moscona, Moscona & Saenz, 1968; Alescio & Moscona, 1969). Striking increases in retinal GS activity can be elicited with hydrocortisone in ovo days in advance of the normal rapid rise of this enzyme (Piddington & Moscona, 1967). Rapid increases in GS activity can also be induced precociously with corticosteroids in organ cultures of young retina (Piddington & Moscona, 1967; Reif-Lehrer & Amos, 1968). The natural steroids most effective in stimulating retinal GS activities in vitro are the 11β-hydroxyl steroids hydrocortisone, corticosterone and aldosterone (Moscona & Piddington, 1967; Reif-Lehrer, 1968).
Some bio-electric parameters of early Xenopus embryos
Authors: Palmer J. F. , Slack Christine 
Published: April 2021

ABSTRACT
Membrane potential and resistance were measured in eggs, cleavage stages and blastulae of the South African toad Xenopus laevis, using intracellular microelectrodes.
The membrane potential increased from – 6·5 ±2 mV in eggs to –57 ±8· 0 mV at the mid-blastula stage.
The input resistance of fertile eggs ranged from 0·5 MΩ to 5 ·0 MΩ corresponding to a specific resistance of 20–200 kΩ cm2. During the first two or three division cycles the input resistance usually decreased by a factor of 2– 10 and then subsequently rose during the blastula stages from a mean value of 600 ± 100 kΩ at stage 5 to 2·0 ±0·5 MΩ at stage 8.
At all developmental stages examined, point polarization of a surface cell in the embryo by rectangular current pulses of 0·5–6 × 10−8 A produced voltage deflexions in other surface cells. This was seen even when several (7–8) cell junctions intervened between the current passing and voltage recording microelectrodes at distances of more than 1 mm. These measurements suggest that the junctional resistance is low compared with that at the surface, though the geometrical arrangement of cells is not favourable for calculation of absolute values of membrane resistance.
Current spread between cells occurred apparently less easily during mid-blastula stages than at earlier stages in development, perhaps indicating an increase in junctional resistance during development.
A comparison has been drawn between the present measurements and similar ones made in another amphibian, Triturus.
Histochemical observations on early implantation in the mouse
Authors: Smith M. S. R. , Wilson I. B. 
Published: April 2021

ABSTRACT
Acid phosphatase, polysaccharide complexes and lipids were studied in the uterus and embryo of the mouse from 90 to 120 h post coitum (p.c.).
The pattern of acid phosphatase-rich vesicles (ERV) in the uterine epithelium and its manner of degeneration are discussed.
At 90 h p.c. there are large ERV in the inner cell mass indicating degenerating cells; these are not detectable at 96 h p.c.
A border of lysosomes is prominent in regions of the peripheral trophoblastic cytoplasm adjoining the epithelium at 96 h p.c. and this may be involved in membrane changes which facilitate closer contact and interactions between the embryonic and maternal cells.
Discrete aggregates of large ERV are present in the epithelium and trophoblast at sites scattered around the abembryonic region, from 96 to 104 h p.c.
From 94 to 100 h p.c. macrophage-like cells can be found in the uterine epithelium.
In the later stages of implantation, 110–120 h p.c., the pattern of acid phosphatase-rich vesicles becomes progressively more complicated with the whole of the epithelium around the blastocyst gradually becoming degenerate.
Structure and developmental tendency of the dorsal marginal zone in the early amphibian gastrula
Authors: Ikushima Nobushige , Maruyama Setsuko 
Published: April 2021

ABSTRACT
The peripheral surface of a fertilized, uncleaved egg is subdivided through cleavage and is allotted to constituent cells. This is called the primary surface. In an early morula a constituent cell has two kinds of surfaces: the primary surface, and the secondary surface, which does not participate in forming the periphery of the embryo. Electron-microscopic observations showed structural differences between the two surfaces.
When the dorsal marginal zone of an early gastrula of Hynobius nebulosus is excised and immersed in Feldman’s solution, the piece can easily be separated into two layers: the outer layer, whose constituent cells are given a share of the primary surface, and the inner layer, whose constituent cells are completely covered only by the secondary surface.
Both an explanted piece of the outer layer and an intact double-layered piece show three kinds of movement: spreading, convergence followed by stretching, and spherical thickening. The inner layer is kinetically very inert, showing slight spreading and thickening.
An explanted piece of the outer layer differentiates into axial mesodermal structures, while the inner layer does not.
When a piece of either the inner or the outer layer is implanted in the blastocoel of another gastrula, it induces deuterencephalic and spino-caudal structures and seems to differentiate into axial mesodermal structures.
Differences of kinetic properties and differentiation are considered to result from the fact that the outer layer has the primary surface, while the inner layer does not.
Functional effects of the primary surface on the movement of tissues and differentiation are discussed.