bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interprétation des régénérais multiples chez les Insectes
Authors: Bulliére Désiré 
Published: April 2021

ABSTRACT
Depuis très longtemps les auteurs se sont attachés à l’étude des régénérais surnuméraires chez les Insectes et ont cherché à reproduire expérimentalement ces malformations, afin d’en mieux comprendre la genèse. A la fin du 19° siècle, Bateson (1894) a essayé de trouver une explication aux variations naturelles en formulant des lois qui régissent ces variations. Bodenstein (1937, 1941) a, le premier, réussi à provoquer expérimentalement l’apparition de régénérais multiples chez Phryganidia california et P. cardini. A sa suite, Balazuc (1948, 1955) et plus récemment Penzlin (1965), Bart (1965 a, b, 1966) et Bohn (1965 a, b) ont tenté de donner une explication à la production expérimentale de régénérais multiples. Ces études, faites sur les Insectes, ne s’accordent pas toujours avec les conclusions de Della Valle (1913) et de Przibram (1921) qui ont obtenu des régénérats multiples chez les Batraciens urodèles. D’après Przibram, la section incomplète d’un membre conduit à l’élaboration d’un régénérât à partir de chacune des deux lèvres de la plaie, maintenues écartées artificiellement.
A light and electron microscopic study of cell behavior and microtubules in the embryonic chicken lens using Colcemid
Authors: Pearce Thomas L. , Zwaan Johan 
Published: April 2021

ABSTRACT
The first sign of differentiation of the lens rudiment is a change in cellular shape, as in many other embryonic systems (Tilney, 1968 a). This occurs some time before the beginning of overt chemical differentiation, the appearance of specific proteins (Zwaan, 1968). From stage 11 (Hamburger & Hamilton, 1951), just after the optic cup contacts the surface ectoderm, to stage 13, before the onset of invagination, the lens Anlage is rapidly transformed from a cuboidal to a high columnar epithelium, a process described by McKeehan (1951) as palisading. This is slightly preceded in time by nuclear rearrangement. First irregular in outline and randomly oriented, the nuclei become smooth and oval, and aligned at right angles to the surface. They take up positions in the basal portions of the cells (McKeehan, 1951).
Dissociation of sensory ganglia from the embryonic chick by pronase and other dispersing agents
Authors: Banks Barbara E. C. , Banthorpe D. V. , Lamont D. Margaret , Pearce F. L. , Redding Katharine A. , Vernon C. A. 
Published: April 2021

ABSTRACTThe gross effect of protein factors from mouse salivary glands and certain snake venoms on the growth, in tissue culture, of explants of sensory ganglia from chick embryos is well established (Levi-Montalcini, 1964, 1965; Angeletti, Calissano, Chen & Levi-Montalcini, 1967; Banks et al. 1968; Varon, Nomura & Shooter, 1967a, b). The effects of these substances, called nerve growth factors, on individual neurons in vitro have, however, been little investigated and no quantitative studies have been reported. In order to make such a study we required a method of making cell suspensions of high density from chick embryonic sensory ganglia: the target tissue normally used for the assay of nerve growth factors.
Mandibular growth retardation as a cause of cleft palate in mice homozygous for the chondrodysplasia gene
Authors: Seegmiller Robert E. , Fraser F. Clarke 
Published: April 2021

ABSTRACT
Defective chondrogenesis in C57BL mice homozygous for the chondrodysplasia gene leads to deformity of limbs, ribs, trachea, mandible and palate. Since formation of the secondary palate depends upon coordinated development of several craniofacial structures, the presence of micrognathia and cleft palate in cho/cho newborn mice suggested a cause-and-effect relation between these two deformities. To determine whether or not lower jaw shortening coincided with the time of palate closure, heads from mutant and control littermates previously rated morphologically were examined in median sagittal section. Of six parameters analyzed, growth rates for mutant mandible and anterior vertical dimension were significantly less than those of controls from the beginning of control palate closure. Since there is evidence that intrinsic shelf force is normal, these observations suggested that, during palatogenesis, growth retardation of Meckel’s cartilage did not allow forward displacement of the tongue, and that the consequent failure to straighten the tongue impaired shelf movement. The data support the concept that growth of Meckel’s cartilage is necessary for normal palate formation.
In vitrodevelopment of palatal tissues from embryonic mice:III. Interactions between palatal epithelium and heterotypic oral mesenchyme
Authors: Tyler Mary S. , Koch William E. 
Published: April 2021

ABSTRACTThe epithelium of the secondary palate from embryonic mice (12-14 days of gestation) was enzymatically separated from the palatal mesenchyme and was cultured in association with mesenchyme from the embryonic tongue, incisor, and salivary gland. The histological differentiation of the epithelium in each type of heterotypic recombination was always palatal. Tongue mesenchyme supported full histodifferentiation of the palatal epithelium, whereas incisor mesenchyme supported only a limited histodifferentiation in the epithelium. Salivary gland mesenchyme in direct combination with palatal epithelium influenced the epithelium to become organized into a system of ducts and acini typical of glandular morphogenesis; histodifferentiation of the epithelium, however, was palatal. Salivary gland mesenchyme grown in isolation did not undergo glandular morphogenesis.The results demonstrate that histodifferentiation of palatal epithelium may be supported by various types of mesenchyme. That a glandular morphogenesis can be induced in the epithelium without altering epithelial histogenesis indicates that histogenesis and morphogenesis are not necessarily interdependent parameters of epithelial differentiation. The ability of palatal epithelium to express its original histogenetic determination when separated from its mesenchyme as early as 12 days of gestation and recombined with heterotypic mesenchyme shows that the histogenetic program of the epithelium is relatively stable at an early stage in palatal development.
Karyotype analysis of teratocarcinomas and embryoid bodies of C3H mice
Authors: Iles S. A. , Evans E. P. 
Published: April 2021

ABSTRACTKaryotype and capacity for differentiation were determined in four transplantable teratomas, and their embryoid bodies, derived from C3H mouse embryos. An apparently normal karyotype was retained by one tumour and one subline that were able to differentiate into a wide range of tissues, but some chromosomal alterations were found in the two tumours and one subline that showed almost identical restrictions in their capacity for differentiation. Trisomy for chromosome 11 was shared by all three restricted tumours; two of the tumours had similar length changes in the same two chromosome (1 and 14) while the third was generally trisomic for four other chromosomes.
Modulation of alphafetoprotein synthesis in the early postimplantation mouse embryo
Authors: Dziadek M. 
Published: April 2021

ABSTRACT
The visceral endoderm of mouse egg cylinders on the 7th and 8th days of gestation is divided into the visceral embryonic (VE) endoderm cell population which synthesizes alphafetoprotein (AFP), and the visceral extra-embryonic (VEX) endoderm population which does not synthesize AFP. Embryonic (E) and extra-embryonic (EX) ectoderm and visceral endoderm tissues were enzymically separated, reassociated in different combinations, and cultured in vitro for 48 h. The immunoperoxidase reaction on sections of cultured tissues showed that both VE and VEX endoderm cells synthesize high levels of AFP when cultured in isolation or in association with E ectoderm, but do not synthesize AFP when in close association with EX ectoderm. Both 7th and 8th day VEX endoderm cells synthesize detectable levels of AFP 12 h after isolation, and contain high levels by 24 h. It is concluded that both VE and VEX endoderm cells have the ability to synthesize AFP, but modulation of expression occurs through an inhibitory influence of the EX ectoderm.
Postembryonic development of the visual system of the locust, Schistocerca gregaria
Authors: Anderson Hilary 
Published: April 2021

ABSTRACT
In the compound eye of the locust, Schistocerca gregaria, neurons from the retina project to the lamina in a precise topographical mapping.
The formation of this projection was investigated in grafting experiments which altered the spatial or temporal relationship between the retina and the lamina.
The results show that retina axons tend to grow along the paths of adjacent axons, with no indication of specificity for their normal termination sites.
It is suggested that the orderly sequence of retina differentiation during normal development plays a major role in imposing pattern both upon the developing projection and, through some form of inductive interaction between retina and lamina neurons, upon the lamina.
Studies on dwarf larvae developed from isolated blastomeres of the starfish,Asterina pectinifera
Authors: Dan-Sohkawa Marina , Satoh Noriyuki 
Published: April 2021

ABSTRACTNot only a whole denuded egg, but also blastomeres isolated from 2-, 4- and 8-cell starfish embryos developed into morphologically normal, but dwarf bipinnariae, the sizes of which were roughly proportionate to that of the respective original blastomeres. Some of the blastomeres isolated from the 16-cell stage were also capable of developing into the larval stage. All isolated blastomeres divided in good synchrony with the control embryos. Blastulae of all groups gastrulated within quite a short range of time, around 14·5 h after insemination at 20 ± 1 °C, although one-third of the 1/8-blastula missed this chance but gastrulated by 19-5 h. The number of constituent cells of the 1/8-gastrula was counted to be about 560, which corresponds roughly to one-half that of the 1/4-, one-fourth of the 1/2- and one-eighth of the 1/1-gastrula. This ratio also fitted roughly for the total cell volume.The results are compared with those of other invertebrate species, as well as of some vertebrates, and are discussed in connexion not only with the concepts of ‘regulative’ and ‘mosaic’ eggs, but also with a criterion that does not fit into either of these; the developmental system of the mammals.
Cell adhesiveness and embryonic differentiation
Authors: Bellairs Ruth , Curtis A. S. G. , Sanders E. J. 
Published: April 2021

ABSTRACT
The aim of the investigation was to decide whether changes in cell to cell adhesiveness took place during embryonic differentiation. The technique of Curtis (1969) was used to measure the adhesive behaviour of several types of ectodermal, neural and mesodermal cells of the chick embryo at stages 7 and 12 of differentiation. Cells dissected from segmented mesoderm were found to be more adhesive than cells from unsegmented mesoderm. Cells from the ectoderm were more adhesive than those from the neural tissue, at both stages 7 and 12. Cells from both ectoderm and neural tissue became more adhesive between stages 7 and 12. It is concluded that an increase in adhesiveness may play a role in somite segmentation, but not in neural tube formation.
Biochemical changes in developmentally retarded Xenopus laevis larvae
Authors: Doyle M. J. , Maclean N. 
Published: April 2021

ABSTRACT
Premetamorphic tadpoles of Xenopus laevis reared in water containing 0·01 % propyl-thiouracil are developmentally retarded and metamorphosis is prevented. When uncrowded, they continue to grow to a giant size. Moderate crowding leads to a slower rate of growth. Thus morphologically premetamorphic tadpoles were produced with lens diameters appropriate to either normal premetamorphic, climactic or post-metamorphic animals. The lens crystallins of such tadpoles have been separated by immunoelectrophoresis and polyacryl-amide gel electrophoresis. The crystallin pattern was correlated with lens diameter rather than with body stage. Giant retarded larvae possessed crystallin patterns identical to those of normal adults. The thyroid antagonist propylthiouracil is therefore unable to prevent the lens crystallin transition, the beginning of which is normally temporally correlated with metamorphosis.
X-chromosome activity in preimplantation mouse embryos from XX and XO mothers
Authors: Monk Marilyn , Harper Mary 
Published: April 2021

ABSTRACT
Embryos from XO female mice begin development with half the activity levels of an enzyme (HPRT) coded for by a gene on the X chromosome, compared with embryos from XX females. Groups of unfertilized eggs and individual embryos at the 8-cell, morula and blastocyst stages were assayed for HPRT activity. An autosomally coded enzyme (APRT) was assayed simultaneously in the same reaction mix as a control. There is a substantial increase in HPRT activity by the 8-cell stage. However, the mean activity of HPRT in embryos of XO mothers remains half that in embryos of XX mothers. This suggests a signifi- cant maternally inherited component of HPRT activity in 8-cell embryos. By the 9- to 16-cell morula stage the HPRT activities in the two groups of embryos become similar due, pre- sumably, to a transition to embryo-coded activity; HPRT activities in individual morulae from XX mothers show a bimodal distribution consistent with the hypothesis that both X- chromosomes are active in XX embryos at this stage.
The effects of some Robertsonian chromosome combinations on the seminiferous epithelium of the mouse
Authors: Redi C. A. , Garagna S. , Hilscher B. , Winking H. 
Published: April 2021

ABSTRACT
In Mammals, structural rearrangements of the karyotype cause considerable trouble to the spermatogenic process. Making use of an experimental animal model of Robertsonian chromosomal variation in the house mouse (Gropp, Winking & Redi, 1982a) the effects of these chromosome structural rearrangements on the spermatogenic process were studied in fertile and chromosomally derived subfertile and sterile mice. Each karyotype condition was related to the cytological composition of the twelve stages of the seminiferous epithelium, studied in PAS-haematoxylin-stained testicular sections, with the following results: in subfertile males there is a depletion of spermatogonia in the regenerating compartment but their differentiation is not affected. In the sterile males there is degeneration of primary and secondary spermatocytes and massive spermatid degeneration.Spermatocyte development is retarded in nearly 50 % of the spermatocyte population in subfertile males. Moreover the ratio between primary spermatocytes and spermatids is reduced to about 1:2 in subfertile males, while the few spermatids produced in sterile males had degenerated during stages I to VIII.The number of Sertoli cells/100 μm throughout the cycle of spermatogenesis is the same in the three conditions studied. These data indicate that the spermatogenic process is affected by structural changes not only at the meiotic level (primary spermatocyte failure to follow the normal pattern of differentiation and occurrence of defective spermatids) but also at the premeiotic stage, when undifferentiated spermatogonia are regenerating.
Clonal analysis of intestinal crypt populations in mouse aggregation chimaeras
Authors: H. Schmidt Günter , Garbutt David J. , Wilkinson Maureen M. , Ponder Bruce A. J. 
Published: April 2021

ABSTRACT
The epithelium of each individual intestinal crypt in adult mouse aggregation chimaeras is composed of cells of a single parental genotype (Ponder et al. 1985). Using a carbohydrate polymorphism recognized by Dolichos biflorus agglutinin as a strain-specific marker on entire sheets of intestinal mucosa, we have analysed the two-dimensional mosaic patterns of patches of the chimaeric intestinal crypt population. The relative proportions of each genotype varied greatly along the length of any one intestine. In chimaeras with highly unbalanced proportions, the minority component occurred as discrete patches. Patches of single or a few crypts were most frequent, but a smaller number of much larger patches was always present. The size frequency distribution of discrete patches was highly concave and departed significantly from a geometric distribution (a model for non-differential proliferation), but fitted the more skewed negative binomial model. The data are consistent with the interpretation that most progenitor crypts never or rarely divide, while a minority proliferate to a greater extent. We discuss ways in which our system could be analysed further to examine this interpretation. Our results also support Whitten’s (1978) conclusion from a computer simulation that the mean patch size, as it has previously been used in statistical analyses of chimaeric tissue, ‘is not a reliable statistic on which to judge mosaicism’.
Transcription of similar sets of rare maternal RNAs and rare nuclear RNAs in sea urchin blastulae and adult coelomocytes
Authors: Kleene Kenneth C. , Humphreys Tom 
Published: April 2021

ABSTRACT
We studied the sequences transcribed in the rare class of hnRNA and the rare maternal RNA set in blastula embryos and a tissue of adult sea urchins, coelomocytes. About 26 % of labelled single-copy DNA formed hybrids which bound to hydroxyapatite after three cycles of hybridization with nuclear RNA from blastulae and coelomocytes. This corresponds to transcription of about 50 % of the single-copy genome by both cell populations. To compare the rare hnRNA sequences synthesized by blastulae and coelomocytes directly, labelled single-copy DNA was hybridized with blastula nuclear RNA to high RNA C0t, fractionated into sequences complementary and non-complementary to blastula nuclear RNA by chromotography on hydroxyapatite, and then each fraction was rehybridized with nuclear RNA from blastulae and coelomocytes. About 62 % of the labelled DNA complementary to blastula nuclear RNA and about 1·5 % of the labelled DNA non-complementary to blastula nuclear RNA hybridized with nuclear RNA from both cell populations. Thus, coelomocytes and blastula embryos transcribe essentially the same single-copy sequences in the rare hnRNA class. A probe for the rare maternal RNA set was isolated by hybridizing single-copy DNA with total egg RNA to high RNA C0t. 65–67 % of this probe hybridized with whole-cell RNA from eggs, blastulae, plutei and coelomocytes demonstrating that essentially all rare maternal RNAs are present, and presumably transcribed, in blastulae, plutei and coelomocytes.
Separation of wound healing from regeneration in the cockroach leg
Authors: Truby Paul R. 
Published: April 2021

ABSTRACT
It has been shown that after a critical point in the moult cycle of a cockroach, wound healing can occur but regeneration of pattern does not take place until the following intermoult period. Leg removal after the critical point is used to separate the processes of wound healing and leg regeneration. This permits the study of patterns of cell division resulting from wound healing to be distinguished from those involved in leg regeneration.
During wound healing, cell division occurs in the epidermal cells of approximately the distal half of the trochanter. The cells then return to the resting state until after the next ecdysis. Regeneration starts with cell division occurring in the distal half of the trochanter, and then spreading to include cells of the proximal trochanter and distal coxa. This spread and the following patterns of growth and redifferentiation appear to be the same as for regeneration following leg removal prior to the critical point, with the more distal structures completing early stages of regeneration first.
Scanning electron micrographs of the cuticle of the trochanter after the ecdysis following leg removal support the evidence from the patterns of cell division in suggesting that the distal half of the trochanter is dedifferentiated during wound healing.
Synthesis of apolipoproteins, alphafoetoprotein, albumin, and transferrin by the human foetal yolk sack and other foetal organs
Authors: Shi W-K. , Hopkins B. , Thompson S. , Heath J. K. , Luke B. M. , Graham C. F. 
Published: April 2021

ABSTRACT
Fragments of human foetal organs and blood at 5 –11 weeks of postfertilization development were cultured in radioactive protein precursors. The secreted products were characterized by immunoprecipitation, and by measuring the mobility of the immunoprecipitates on polyacrylamide gels. It was found that secondary human yolk sacks secreted apolipoproteins A1 and B. The work of previous authors on the synthesis of other serum products by this organ and by the foetal liver and by the foetal intestines was confirmed. Within the yolk sack, the endoderm, the blood cells, and the outside epithelium reacted with antibodies against apolipoprotein Al and transferrin. By metabolic labelling of umbilical cord blood, it was found that blood did not secrete apolipoproteins Al and B. Blood cells could therefore not be a source of these secreted products.
Cell surface changes during cleavage of newt eggs: scanning electron microscopic studies
Authors: Ohshima Hiromasa , Kubota Tomoyuki 
Published: April 2021

ABSTRACT
Scanning electron microscopic studies were carried out on changes of the cell surface during the first cleavage of eggs of the newt, Cynopus (Triturus) pyrrhogaster. A dense population of elongated microvilli, which initially covered a double line indicating the initial furrow and stress marks running on each side of it, became located inside the pigmented area a little apart from its border with the unpigmented area when this borderline was established. This finding, together with data of carbon marking experiments, indicates that membrane growth occurs not only at the presumptive unpigmented surface, but also in a small portion of the presumptive pigmented area adjoining it. During cleavage within the vitelline membrane, a stable intercellular junction at the border of the pigmented and unpigmented surfaces was formed through the following successive processes: the appearance of individual lamellipodia on the borderline; contact of their apical filopodia with those of the opposite blastomere; contact of the lamellipodial bodies; and complete joining of the whole of the lamellipodia in contact. In cleavage of demembranated eggs, in which there is no chance of contact of lamellipodia of the two blastomeres, each lamellipodium persisted in an isolated state until the onset of the next division. In most cases, many strained or broken threads were seen across the space formed by opening of opposing blastomeres, at their peripheries. These threads were cytoplasmic in nature and showed cell contact. Similar threads were found stretched between blastomeres when the closed furrow was opened in medium containing EGTA.
The Development of Pandora inaequivalvis (Linné)
Authors: Allen J. A. 
Published: April 2021

ABSTRACT
Artificial fertilization of the eggs of P. inaequivalvis has been carried out and the development followed to the dissoconch stage. The development is very rapid and metamorphosis occurs in less than 4 days. The veliger spends less than one day in the plankton and this is the first record of a short-lived planktotrophic lamellibranch larva. The speed of development is related to the relatively large (105– 125 μ diameter) size of the egg and its contained food reserves. There is minimal dispersal of the young from the very localized habitat of the adult. No protonephridia or larval eyes are developed and the gut follows a simple course in comparison with other lamellibranch larvae. The gills do not develop until after metamorphosis and the large palps and foot produce the ciliary currents connected with respiration, feeding, and cleansing between the loss of the velum and the development of the functional gill.