bluuebunny/crossref_metadata_2025_split huggingface dataset:
X-ray Inactivation of Nuclei as a Method for Studying their Function in the Early Development of Fishes
Authors: Neyfakh A. A. 
Published: April 2021

ABSTRACT
The effect of high radiation doses (20-60 kr.) on different stages of the early development of the loach (Misgurnus fossilis L.) was studied. Analysis of dose dependence shows that a radio-sensitive component (presumed to be the nuclei) is affected maximally by such doses, whereas a radio-resistant component (presumed to be the cytoplasm) is not affected significantly. The use of such radiation doses is, therefore, a means of investigating the role of nuclei in development. Irradiation with these doses at any time from fertilization to early blastula leads to the arrest of development at one stage—the late blastula—and to death some hours later. Irradiation at any time during the period from late blastula to mid-gastrula similarly leads to arrest of development at one stage—the end of gastrulation. Irradiation during the period from early to late blastula results in the arrest of development at different stages of gastrulation depending on the moment of irradiation. Irradiation after the mid-gastrula results in the arrest of development at different stages of organogenesis, depending also on the moment of irradiation. The results cannot be explained by changes of nuclear sensitivity, nor by non-specific critical periods in development. They can be explained by changes in the role of nuclei in development, by periods of specific dependence on the function of nuclei. The independence of the stage of developmental arrest on the stage of irradiation, when irradiating from fertilization up to early blastula and from late blastula up to mid-gastrula, shows the relative inactivity of nuclei during these periods of normal development. The strong dependence of the stage of development reached at arrest on the stage of irradiation, when irradiating the early to late blastula and after the mid-gastrula stages, demonstrates the activity of nuclei in development during these periods. The conclusion may be drawn that in the early development of the loach the nuclei function periodically, each period of activity ensuring a subsequent episode of development. Nuclear activity during ovogenesis ensures the development of the egg up to the stage of the late blastula; nuclear activity during the early and mid-blastula stages ensures gastrulation. Development of axial organs and further organogenesis is ensured by nuclear function beginning from the mid-gastrula stage.
Tail Regeneration in the Geckonid Lizard,Sphaerodactylus
Authors: Hughes Arthur , New Denis 
Published: April 2021

ABSTRACTTail regeneration in the Geckonid Lizards Sphaerodactylus goniorhynchus and argus is described. The rate of growth of a first regenerate, after a latent period of 10–12 days, is about 0·47 mm. per day. Subsequent regenerates grow more slowly. The tissues of the new tail are derived from a regenerative blastema which is formed beneath the epidermis covering the broken surface of the tail. A flaskshaped outgrowth of the ependymal epithelium is a centre for the proliferation of new cells. The outer part of the regenerative blastema is a zone of myogenesis, which becomes divided into the same number of muscle bands as in the original tail. Each muscle band becomes segmented, and motor nerves enter the intersegmental planes. At these sites a positive reaction for esterases is first seen. Multinucleate muscle fibres, which stretch from one intersegmental plane to the next, arise by the fusion of myoblastic cells. The regenerate is innervated by branches of the last three remaining pairs of spinal nerves. These branches keep pace with the growth of the regenerate, and form longitudinal nerves. Their terminal fibres enter the new ectoderm on the 4th day. Nitrogen mustard applied in solution to the outer surface of the regenerating area may inhibit, or slow down, the new growth. Degeneration of each type of cell within the regenerate is caused by nitrogen mustard, but melanocytes become more abundant than normal. A regenerate subsequent to one inhibited by nitrogen mustard grows as fast, or even faster, than a normal first regenerate, and again contains an excess of melanocytes.
The Development of the Cornea in the Chick
Authors: Meyer David B. , O’rahilly Ronan 
Published: April 2021

ABSTRACTThe development of the cornea in the chick, based on the microscopical examination of serial sections of 108 morphologically staged chick embryos between stage 26 and hatching, is described. A description of the adult cornea is also provided. Correlations between the internal histogenesis of the cornea and the external morphology of the chick embryo have been established from the use of staged embryos, so that the probable state of development of the cornea can be assessed from surface appearances only. The cornea of the chick, at stage 26, consists of an anterior epithelium, an acellular postepithelial layer, and a mesothelium. Mesenchymal cells (corneal ‘corpuscles’) begin to infiltrate the postepithelial layer at stage 27. By stages 29–31 these cells occupy a continuous layer, the substantia propria, which comprises the entire extent of the postepithelial layer except for an anterior, acellular band subjacent to the anterior epithelium. The anterior band becomes progressively thinner and disappears at stage 36, the substantia propria then extending across the entire distance between the anterior epithelium and the mesothelium. The anterior limiting lamina first appears at stage 39. It closely resembles and is often confused with the temporary anterior band of the postepithelial layer. The posterior limiting lamina was not identified with certainty in any of the embryonic corneae examined. It has been stressed that embryological studies in which external staging and internal development are correlated provide a more precise interpretation of developmental processes, and are an essential prelude to experimental, physiological, biochemical, and histochemical investigations of embryonic development.
The Formation of the Second Maturation Spindle in the Eggs of Succinea, Physa, and Planorbis
Authors: Raven Chr. P. 
Published: April 2021

ABSTRACT
In a previous communication (Raven, Escher, Herrebout, & Leussink, 1958) the maturation of the egg was described in Agriolimax reticulatus, Limax flavus, and Limnaea stagnalis, with special regard to the formation of the second maturation spindle. In the three species the second maturation spindle arises by direct transformation from the deep centrosphere of the first maturation amphiaster. In A. reticulatus and Limax flavus this centrosphere contains a pair of centrioles which move apart to opposite poles of the developing spindle. This is symmetrical and develops an aster at both ends, arising in the cytoplasm outside the original centrosphere.
The Apparent ‘Corneal Specificity’ of Sensory Neurons
Authors: Székely George 
Published: April 2021

ABSTRACT
Tactile stimulation of a forelimb grafted into the gill region in urodeles (Pleurodeles waltlii and Triturus vulgaris) yields no corneal reflex. If the foot of such a grafted limb has been cut off, stimulation of the resulting regeneration blastema evokes a corneal reflex in the same way as does stimulation of the cornea of an eye transplanted into this region. After complete regeneration of the foot the corneal reflex disappears, butJ. Embryol. exp. Morph. from a new regeneration blastema developing after a second and in some cases even after a third amputation the corneal reflex can again be elicited. These results are considered to be inconsistent with the ‘modulation theory’ of Weiss.
The Effects of Chorioallantoic Grafts on the developing Chick Embryo:II. Studies of Adult Antigens in the Duodenum and Spleen
Authors: Alten Pierson J. Van 
Published: April 2021

ABSTRACTThe development of adult duodenal antigens in the embryonic duodenum was studied by means of the Ouchterlony agar diffusion technique. In 11-, 12-, and 13-day embryonic duodena there were two antigens; by the 14th day three antigens; in the 15-, 16-, and 17-day duodena four antigens; while in 18-, 19-, and 20-day duodena there were only three antigens with a fourth antigen again present in the 21-day duodenum. The disappearance of the fourth antigen found in 15-, 16-, and 17-day duodena was attributed to a change in molecular configuration of the antigen in the process of differentiation. Following grafts of adult duodenum there was an increase of three antigens observed in the host duodenum and an increase of one antigen in the host spleen. When adult spleen was grafted there was no increase in the number of antigens in the host spleen, but an increase of one antigen was observed in the duodenum. The results are discussed in the light of the organ-specific growth stimulation hypothesis, but this is rejected because it cannot account for the generalized effects observed.
The Organ Specific Action of Thyroxin in Visual Pigment Differentiation
Authors: Wilt Fred H. 
Published: April 2021

ABSTRACT
The stimulation of conversion of visual pigment from porphyropsin to rhodopsin in eyes of larvae of R. catesbeiana has been effected by local implantation of thyroxin-cholesterol pellets. An eye which has received a pellet consistently shows a greater increase in the vitamin A-l content, an index of rhodopsin content, than does the contralateral sham-operated eye, or eyes from animals with pellets placed in the abdominal cavity. It is concluded that photopigment conversion is a direct response of the eye to thyroxin or its physiological derivative.
Neural induction and the structure of the target cell surface
Authors: Duprat A. M. , Gualandris L. , Rouge P. 
Published: April 2021

ABSTRACT
Lectins (SBA and PSA) were used to provoke crowding and structural modifications of the presumptive ectoderm cell surface in order to investigate the role of the membrane organization of the competent target cells in neural induction. Are specific characteristics of the cell surface essential for this phenomenon to occur?
From amphibian gastrulae, it is possible to obtain neural induction in vitro by association of presumptive ectoderm (target cells) with chordamesoderm (inductor tissue) : 4 h of contact is sufficient in Pleurodeles waltl for transmission of the inductive signal.
Very quickly, the treatment of the normal ectoderm by lectins (SBA-FITC or PSA-FITC) provoked surface modifications.
Lectin-treatment (50 μg ml-1, 30 min) of presumptive ectoderm did not result in any neural induction.
Lectin-treatment (50 μg ml-1, 30 min) of presumptive ectoderm previous to its association with the natural inductor for 4 h, disturbed the phenomenon : no induction.
Similar treatment followed by association with the inductor for 24 h : induction.
Treatment of SBA or PSA with their respective hapten inhibitors prior to addition to ectodermal cells completely blocked the suppressive effects on induction.
The structural integrity of the membrane of competent target cells is necessary for neural induction to occur. The cell membrane could thus play, directly or indirectly, an active role in the specificity of this process.
Axial organization of the regenerating limb : asymmetrical behaviour following skin transplantation
Authors: Maden M. , Mustafa K. 
Published: April 2021

ABSTRACT
An extensive series of skin grafting operations has been performed to investigate axial organization in the regenerating axolotl limb. Semicircular cuffs of skin from either anterior, posterior, dorsal or ventral surfaces were exchanged between right and left limbs thereby creating limbs with double anterior, double posterior, double dorsal or double ventral skin, all with normal internal tissues. Both fore and hindlimbs were used at both upper and lower limb levels. Following amputation through the grafted region the resulting regenerates were analysed both by whole-mount cartilage staining to observe the pattern of digits and by serial sectioning to observe the pattern of muscles. There were clear asymmetries in ability to produce duplications –posterior to anterior grafts resulted in a consistently high frequency of digital duplications, whereas anterior to posterior grafts produced very few. Similarly, dorsal to ventral grafts resulted in a good frequency of muscle duplications, whereas ventral to dorsal grafts did not. Such asymmetrical behaviour is not predicted by most models involving local cell:cell interactions and the significance of the results for theories of pattern formation is discussed.
The development of the peripheral trigeminal innervation in Xenopus embryos
Authors: Davies Stephen N. , Kitson David L. , Roberts Alan 
Published: April 2021

ABSTRACT
The development of the ophthalmic, maxillary and mandibular nerves has been followed in Xenopus laevis embryos from the first emergence of growth cones from the trigeminal ganglia until the establishment of functional innervation of the skin or cement gland. The course of each main nerve is highly predictable and follows pre-existing openings between blocks of other tissues. The development of the mandibulary nerve was observed most easily. Like that of the other trigeminal nerves it falls into three stages: (1) A pioneer neurite emerges and a nerve forms as other, later neurites fasciculate with this. (2) On reaching the inside surface of the cement gland the neurites separate and penetrate holes in the basal lamina. (3) The neurites grow between the cells they will innervate and form free nerve endings. The scanning EM observations have been confirmed by electrical recordings from trigeminal neurones. The role of pioneer fibres and substrate guidance are discussed.
Protein synthesis during limb regeneration in the axolotl
Authors: Slack J. M. W. 
Published: April 2021

ABSTRACT
A study has been made of limb regeneration in the axolotl using two-dimensional gel electrophoresis of proteins labelled with [35S]methionine.
In the early stages of regeneration seven proteins are identified which are-specific to the mesenchyme and thirteen which are specific to the epidermis. There is very little change in the gel pattern until the onset of overt cytodifferentiation upon which the muscle and cartilage become substantially different both from each other and from the blastemal mesenchyme.
The gel pattern of mesenchyme from the larval limb bud is almost identical to that of the blastemal mesenchyme, while the pattern of the limb-bud epidermis differs somewhat from the blastemal epidermis.
A careful search has been made for differences which might be associated with ‘positional information’ by comparing forelimb with hindlimb, proximal with distal and anterior with posterior. The differences which have been found are all associated with differences in visible cellular composition or in rates of differentiation, rather than with position per se. It is concluded that positional codings cannot be detected by this technique. On the basis of biological experiments, six criteria are proposed by which to assess future searches for positional codings.
Localization of H-2Kk in developing mouse palates using monoclonal antibody
Authors: Melnick Michael , Jaskoll Tina , Marazita Mary 
Published: April 2021

ABSTRACTUsing monoclonal antibodies to H-2Kk antigen, we sought to develop a reproduceable method of in situ localization in embryonic tissue and to determine whether there are specific patterns of H-2 localization in time and space in the developing palatal tissues of B10.A(H-2a) embryonic mice, with and without corticosteroid pretreatment at 12 days gestation. Our procedure employs ethanol-glacial acetic acid fixation, paraplast embedding, and enzymatic predigestion with purified hyaluronidase and neuraminidase. H-2 antigens were detected in palatal mesenchyme as well as basement membranes but not in oral or nasal epithelium. The pattern of distribution in mesenchyme of untreated embryos changed with progressive shelf development: vertical →horizontal →epithelial fusion →epithelial seam degeneration →mesenchymal confluence. Although the palatal shelves of treated embryos remained vertical, corticosteroid treatment does not appear to alter the detectable spatiotemporal distribution of H-2 antigens in developing palates of embryonic B10.A mice.
Ultrastructural immunocytochemical localization of fibronectin in the early chick embryo
Authors: Sanders E. J. 
Published: April 2021

ABSTRACT
Fibronectin was localized using peroxidase and biotin-avidin-ferritin techniques in developmental stages of the chick embryo from laying to primitive streak formation. The primary location of fibronectin at all stages examined was the basal lamina of the epiblast and its associated extracellular material. The remaining tissues showed little or no immunochemical deposit. At the primitive streak stage of development there were some regional differences in the density of the deposit on the basal lamina. Closely adjacent to the primitive streak, where the basal lamina is fragmentary, deposit was sparse or absent. In this, and other regions, mesoderm cell surfaces did not stain except where they closely approached the stained basal lamina or interstitial bodies. Staining was variable in the basal lamina anterior to the primitive streak, but in a number of cases particularly heavy deposit was noted overlying the crescent of late hypoblast. This area seemed to correspond with the anterior fibronectin-rich band reported by others using immunofluorescence localization.
Correlation between blastocyst oxygen consumption and trophoblast cytochrome oxidase reaction at initiation of implantation of delayed mouse blastocysts
Authors: Nilsson B. Ove , Magnusson Claes , Widéhn Sibylle , HIllensjö Torbjörn 
Published: April 2021

ABSTRACT
Delayed blastocysts had an oxygen consumption of 0 ·24 nl/h, while only 4h after an oestrogen injection the respiration had increased nearly two fold, remaining at this level both 8 and 18 h after activation for implantation. The mitochondria of delayed blastocysts exhibited no positive cytochrome oxidase reaction, neither in the trophoblast nor in the embryoblasts. A few mitochondria at 8 h and most of those of blastocysts activated for 18 h were positive. It is suggested that the activation of blastocysts for implantation is initiated by a surge of substrates for glycolysis into the uterine secretion causing an increased energy production by glycolysis which in turn makes possible an increase of the cytochrome oxidase activity of the mitochondria thus getting oxidative phosphorylation into action.
Cell contact and surface coat alterations of limb-bud mesenchymal cells during differentiation
Authors: Zimmermann Bernd , Scharlach Evamaria , Kaatz Roman 
Published: April 2021

ABSTRACTMeasurements of the cell perimeter, cell-cell contact number and length and of the thickness of the surface coat were performed in limb buds of mouse embryos during the process of cell condensation of the chondrogenic cell mass. This study starts with measurements of ‘non-limb’ mesenchyme.of day-9 embryos and ends with the young cartilage of day 13. It is shown that until day 12 all cells in the limb bud are interconnected by cell contacts of the gap-junction type. Contact number and contact length increase during development, but increase about twice as much between central, prechondric cells as between peripheral or distal cells. Later in development, chondroblasts lose their contacts almost completely, whereas between peripheral cells, the amount of cell contacts drops to the initial value of mesenchymal cells. The cell size decreases during chondrogenesis. A decrease in the thickness of the surface coat of the cells during the whole differentiation period is shown. It may be assumed that this ‘wave of cell contacts’ is the last step for the initiation of the chondrogenic differentiation process.
Intestinalization of the area-vitellina endoderm cultured in association with digestive-tract mesenchymes
Authors: Masui Tohru 
Published: April 2021

ABSTRACT
Small-intestine-type differentiation of the area-vitellina endoderm of quail embryos, cultured in association with digestive-tract mesenchymes of chick embryos, was analysed chronologically with special attention to the appearance of a striated border and its enzymes (alkaline phosphatase and α-glucosidase). Undifferentiated endoderm of the area vitellina differentiated first into yolk-sac parenchyma expressing cysteine lyase, then gradually lost the cysteine lyase activity, and eventually manifested small intestine-type differentiation with the expression of the striated border and its enzymes.
Cell lineage of the Drosophila abdomen: the epidermis, oenocytes and ventral muscles
Authors: Lawrence Peter A. , Johnston Paul 
Published: April 2021

ABSTRACT
We use a new cell marker to study cell lineage of the epidermis, oenocytes and ventral muscles in the Drosophila abdomen. We find that while the epidermal cells and the oenocytes share common precursors until late in development, the muscles derive from a separate lineage. Marked clones in the muscles, but not in the epidermis and oenocytes, can occasionally extend between neighbouring segments, supporting a previous hypothesis that mesoderm cells may not be determined as to segment.
Localization of receptors forDolichos biflorusagglutinin in early post implantation embryos in mice
Authors: Noguchi Motoko , Noguchi Takehiko , Watanabe Makoto , Muramatsu Takashi 
Published: April 2021

ABSTRACTThe distribution of receptors for Dolichos biflorus agglutinin (DBA) was studied by histochemical staining of paraffin sections with HRP- or FITC-DBA in mouse embryos at stages ranging from 4·5 to 12·5 days post coitum. Preimplantation blastocysts did not express DBA receptors. The receptors first appeared in primitive endoderm cells in 5-day embryos. In 5·5- to 7·5-day embryos, both the parietal and extraembryonic visceral endoderm cells expressed the receptors. Reichert's membrane was negative for DBA receptors. The columnar cells of the embryonic visceral endoderm (EVE) strongly expressed the receptors, while the flat cells at the antimesometrial pole of the EVE were negative or patchily positive. In 8- to 9-day embryos, the receptors were expressed in the epithelium of the fore- and hindgut. In 9·5- to 12·5-day embryos, the epithelial cells of various regions of the gut expressed the receptors, although the endodermal cells of the liver and the pancreas, both derived from the foregut, did not express them. In 8- to 12·5-day embryos both the visceral and parietal yolk sac endoderm were positive in DBA receptors. The receptors were localized exclusively on the free surface facing the yolk cavity or on the luminal surface and subjacent cytoplasm. All endodermal cells which were positive are known to have absorptive activity. All other tissues in these stages were negative in DBA receptors.
Les Malformations cardiaques obtenues par l’irradiation aux rayons X du cœur de l’embryon de Poulet
Authors: Douarin par Georges Le 
Published: April 2021

ABSTRACT
Dans un travail antérieur (Le Douarin & Le Douarin, 1959), nous avons étudié les répercussions de l’irradiation du cœur de l’embryon de Poulet sur l’évolution des arcs aortiques. Par ailleurs, les rayons X exercent sur le cœur lui-même une action tératogène.