bluuebunny/crossref_metadata_2025_split huggingface dataset:
Histological studies of whisker regeneration in the hooded rat
Authors: Oliver R. F. 
Published: April 2021

ABSTRACT
A histological study has been made of the follicular changes which occur in vibrissa follicles both after the removal of the dermal papilla alone and the removal of various lengths of follicle root (‘root ends’). The dermal papilla of the vibrissa follicle is not always a discrete and permanent entity, as it has been suggested to be in the feather follicle, since it can be regenerated. No whisker is produced from a follicle or follicle remnant unless a dermal papilla is first regenerated. Dermal papillae regenerate by tissue reorganization at, or just above, the puncture in the base of, or the cut across, the capsule. After removal of the dermal papilla alone, a new papilla of apparently normal size is regenerated, but dermal papillae which regenerate after removal of root ends are smaller than normal. Examination of follicles after the removal of root ends demonstrates that the regeneration of dermal papillae and then whiskers occurs only within the lower third of the vibrissa follicle; there is little or no permanent lengthening, or shortening, of the follicle remnant—whether whiskers are regenerated or not. However, lengths of follicle remaining after removing root ends from within the upper two-thirds of the follicle persist—even though dermal papillae do not regenerate and no fibre production occurs. The histological evidence strongly suggests that cells from the mesenchymal layer contribute to and possibly become the new dermal papilla. After removal of the dermal papilla or root end the outer root sheath cells coalesce to form a column or rod. Basophilia arises within the proximal end of this rod, over which the mesenchymal cells aggregate. These cells form the dermal papilla, first as a small indentation which then increases in size whilst acquiring a strongly basophilic ectodermal matrix.
A study of the effects of colchicine on the process of morphogenesis and induction in chick embryos
Authors: Diwan B. A. 
Published: April 2021

ABSTRACT
The importance of sulfhydryl groups in the process of morphogenesis and induction has been discussed by several workers (Rapkine & Brachet, 1951; Seilern-Aspang, 1959; Brachet, 1960; Pohl & Quertier, 1963; Brachet, 1964). Lakshmi (1962a, b) studied the effects of chloroacetophenone on the develop-ment of chick embryos and emphasized the importance of sulfhydryl groups in morphogenesis and induction. Colchicine is known to affect cell division, probably by its action on sulfhydryl groups of the spindle proteins (Dustin, 1947; Mazia & Dan, 1952). In the present work the effect of colchicine on the processes of morphogenesis and induction in chick embryos has been studied. In order to gain further insight into the mechanism of action of the chemical it is useful to see if its action is reversible. Therefore, an attempt has been made to reverse the action of colchicine by cysteine.
A new gene affecting the morphogenesis of the vestibular part of the inner ear in the mouse
Authors: Deol M. S. , Lane Priscilla W. 
Published: April 2021

ABSTRACT
The discovery of a new semi-dominant gene in the mouse is reported. It is called ‘dancer’, and it belongs to the linkage group XII. The homozygotes have cleft palate and cleft lip, and die soon after birth. The heterozygotes have ab-normal behaviour and a white spot on the head. An examination of the inner ear in the heterozygotes revealed a reduction of the vestibular ganglion, absence of some of its nerves, and widespread mal-formations in the vestibular region. Developmental studies showed that the malformations appear about 2 days after the abnormalities of the ganglion and nerves, and since they are virtually confined to the parts with affected nerve supply they are probably consequent on these abnormalities. A complete correlation between the defects of the semicircular ducts and of their nerves strongly suggests that the nerve plays an essential part in the morphogenesis of the proximal end of the duct. The failure of the otoliths to form in the utricle in the absence of the macula indicates that the otoliths are probably secreted by the macula.
On the constancy of the number of villi in the duodenum of the post-embryonic domestic fowl
Authors: Clarke Rufus 
Published: April 2021

ABSTRACT
Counts performed on whole mounts of late embryonic and of adult chicken duodenum demonstrate that the number of villi present at these two stages of development is approximately the same. Growth occurs by increase in the size of the villi. The crypts of Lieberkühn increase greatly in number and depth, but change little in diameter.
Studies on induction by substances containing sulphydryl groups in post-nodal pieces of chick blastoderm
Authors: Waheed M. Abdul , Mulherkar Leela 
Published: April 2021

ABSTRACT
The importance of sulphydryls in morphogenesis is being increasingly recognized. In the study of the role of thiols in amphibian and avian development one of the methods of approach has been to subject early embryonic stages to the action of reagents such as chloroacetophenone, monoiodoacetic acid, oxidized glutathione and mercaptoethanol (Beatty, 1949; Rapkine & Brachet, 1951; Deuchar, 1957; Brachet & Delange-Cornil, 1959; Pohl & Brachet, 1962; Lakshmi, 1962a). One common effect seen in most of the above experiments is that in treated embryos the nervous system is affected, in that it remains an open thick plate.
The pathogenesis of hydrocephalus in newborn rats deficient in vitamin B12
Authors: Woodard James Carroll , Newberne Paul M. 
Published: April 2021

ABSTRACT
Richardson & Hogan (1946) produced hydrocephalus in rats by feeding a purified casein diet containing all the vitamins available at that time. Almost 2% of the young from females fed the experimental diet were hydrocephalic; female rats fed the same diet supplemented with liver extract gave birth to normal young. It is now thought that this diet was marginally deficient in vitamin B12 (Newberne & O’Dell, 1961). Animals which showed no gross evidence of lesions in the central nervous system had reduced maze-learning abilities as compared to animals on control diets (Whitley, O’Dell & Hogan, 1951).
Developmental genetics of the mutant grandchildless of Drosophila subobscura
Authors: Fielding C. J. 
Published: April 2021

ABSTRACT
A study of the embryology of female-sterile mutants can provide information on the course of normal development, particularly when several mutants affect the same organ system. A favourable situation for an investigation of this kind arises with the formation and migration of the pole cells in Drosophila species. A number of genetic characters are known whose expression in the embryology of the offspring of affected mutant females involves the complete loss of pole cells or a change in their distribution after gastrulation. Thus the sex-linked female sterile mutant fs nasA (Counce & Ede, 1957), and the sex-linked lethals Lf11 (Ede, 1956a), X2 (Ede, 1956b), X27 (Ede, 1956c) and X10 (Ede, 1956d) all show disturbances of the pole cell complement.
Immunochemical investigations on the origin of serum albumin in the chick embryo
Authors: Zaccheo D. , Grossi C. E. 
Published: April 2021

ABSTRACT
Information concerning physical and chemical properties of serum albumin during the development of the chick has been collected by different techniques, e.g. paper, gel and continuous flow electrophoresis, ultracentrifugation and immunochemical methods. However, the results of the various authors are not always in full agreement. The main questions deal with the precise stage of development when serum albumin can first be detected in the circulating blood, and with the heterogeneity of the molecular types in the group of serum albumins. Other aspects of the problem concern the possibility of different origins of serum albumin at various stages and the metabolism of this protein which probably has peculiar features at each intra- and extra-ovular developmental period (Iványi, Hraba & Cerny, 1964).
The ultrastructure of implantation in the golden hamster (Cricetus auratus)
Authors: Young M. P. , Whicher J. T. , Potts D. M. 
Published: April 2021

ABSTRACT
Previous work on the early development of the golden hamster includes the investigation of Ochs (1908), Graves (1945) and Ward (1948), all at the level of the light microscope. Austin (1963) has examined the ultrastructure of the oocytes of the golden hamster while Enders & Schlafke (1965) have observed the pre-implantation stages of pregnancy.
Development of embryonic rat eyes in organ culture
Authors: Armstrong R. Christy , Elias Joel J. 
Published: April 2021

ABSTRACT
Abnormalities of the ocular system which appear in organ culture in Way-mouth’s medium with freshly added glutamine (Armstrong & Elias, 1968) resemble those caused by transitory pteryolglutamic acid (PGA or folic acid) deficiency in vivo (Armstrong & Monie, 1966). The configurations of such malformations as lens herniations, retinal diverticula, and rosette-like formations of the retina are remarkably similar in both cases. The experiments reported in this paper were undertaken in an effort to understand the mechanisms involved in the production of similar abnormalities by two very different experimental conditions: the addition of glutamine in vitro and the transitory deficiency of PGA in vivo.
One series of experiments involved the effects of manipulation of the PGA and glutamine content of the culture medium on eye development in vitro. Parallel studies on PGA-deficiency in vivo were undertaken in conjunction with organ-culture experiments in order to compare the effects on abnormal eye morphogenesis.
Induction neurale chez les Oiseaux à travers un filtre millipore: étude au microscope optique et électronique
Authors: Gallera Par J. , Nicolet G. , Baumann M. 
Published: April 2021

ABSTRACT
Chez les Amphibiens le contact direct entre l’inducteur et l’ectoblaste n’est pas indispensable. Des substances inductrices solubles, probablement de nature pro-téinique, peuvent traverser un filtre millipore et déclencher des inductions neurales (Saxén, 1961; Nyholm, Saxén, Toivonen & Vainio, 1962). Ce filtre constitue pourtant une barrière difficilement franchissable, puisque le pour-centage et la puissance des inductions obtenues sont nettement plus faibles que dans les conditions normales.
Evolution of flowers and inflorescences
Authors: Coen Enrico S. , Nugent Jacqueline M. 
Published: April 2021

ABSTRACT
Plant development depends on the activity of meristems which continually reiterate a common plan. Permutations around this plan can give rise to a wide range of morphologies. To understand the mechanisms underlying this variation, the effects of parallel mutations in key developmental genes are being studied in different species. In Antirrhinum, three of these key genes are: (1) floricaula (flo) a gene required for the production of flowers (2) centrora- dialis (cen), a gene controlling flower position (3) cycloidea (eye), a gene controlling flower symmetry. Several plant species, exhibiting a range of inflorescence types and floral symmetries are being analysed in detail. Comparative genetic and molecular analysis shows that inflorescence architecture depends on two underlying parameters: a basic inflorescence branching pattern and the positioning of flowers. The flo and cen genes play a key role in the positioning of flowers, and variation in the site and timing of expression of these genes, may account for many of the different inflorescence types. The evolution of inflorescence structure may also have influenced the evolution of floral asymmetry, as illustrated by the cen mutation which changes both inflorescence type and the symmetry of some flowers. Conflicting theories about the origins of irregular flowers and how they have coevolved with inflorescence architecture can be directly assessed by examining the role of eye- and cen-like genes in species displaying various floral symmetries and inflorescence types.
Gene duplications and the origins of vertebrate development
Authors: Holland Peter W. H. , Garcia-Fernàndez Jordi , Williams Nic A. , Sidow Arend 
Published: April 2021

ABSTRACT
All vertebrates possess anatomical features not seen in their closest living relatives, the protochordates (tunicates and amphioxus). Some of these features depend on develop mental processes or cellular behaviours that are again unique to vertebrates. We are interested in the genetic changes that may have permitted the origin of these inno vations. Gene duplication, followed by functional diver gence of new genes, may be one class of mutation that permits major evolutionary change. Here we examine the hypothesis that gene duplication events occurred close to the origin and early radiation of the vertebrates. Genome size comparisons are compatible with the occurrence of duplications close to vertebrate origins; more precise insight comes from cloning and phylogenetic analysis of gene families from amphioxus, tunicates and vertebrates. Comparisons of Hox gene clusters, other homeobox gene families, Wot genes and insulin-related genes all indicate that there was a major phase of gene duplication close to vertebrate origins, after divergence from the amphioxus lineage; we suggest there was probably a second phase of duplication close to jawed vertebrate origins. From amphioxus and vertebrate homeobox gene expression patterns, we suggest that there are multiple routes by which new genes arising from gene duplication acquire new functions and permit the evolution of developmental inno vations.
Can the Cambrian explosion be inferred through molecular phylogeny?
Authors: Philippe Hervé , Chenuil Anne , Adoutte Andre 
Published: April 2021

ABSTRACT
Most of the major invertebrate phyla appear in the fossil record during a relatively short time interval, not exceeding 20 million years (Myr), 540-520 Myr ago. This rapid diversification is known as the ‘Cambrian explosion’. In the present paper, we ask whether molecular phyloge netic reconstruction provides confirmation for such an evo lutionary burst. The expectation is that the molecular phy logenetic trees should take the form of a large unresolved multifurcation of the various animal lineages. Complete 18S rRNA sequences of 69 extant representatives of 15 animal phyla were obtained from data banks. After elimi nating a major source of artefact leading to lack of resolu tion in phylogenetic trees (mutational saturation of sequences), we indeed observe that the major lines of triploblast coelomates (arthropods, molluscs, echinoderms, chordates…) are very poorly resolved i.e. the nodes defining the various clades are not supported by high bootstrap values. Using a previously developed procedure consisting of calculating bootstrap proportions of each node of the tree as a function of increasing amount of nucleotides (Lecointre, G., Philippe, H. Le, H. L. V. and Le Guyader, H. (1994) Mol. Phyl. Evol., in press) we obtain a more infor mative indication of the robustness of each node. In addition, this procedure allows us to estimate the number of additional nucleotides that would be required to resolve confidently the currently uncertain nodes; this number turns out to be extremely high and experimentally unfea sible. We then take this approach one step further: using parameters derived from the above analysis, assuming a molecular clock and using palaeontological dates for cali bration, we establish a relationship between the number of sites contained in a given data set and the time interval that this data set can confidently resolve (with 95% bootstrap support). Under these assumptions, the presently available 18S rRNA database cannot confidently resolve cladogenetic events separated by less than about 40 Myr. Thus, at the present time, the potential resolution by the palaeontolog ical approach is higher than that by the molecular one.
The evolving role of Hox genes in arthropods
Authors: Akam Michael , Averof Michalis , Castelli-Gair James , Dawes Rachel , Falciani Francesco , Ferrier David 
Published: April 2021

ABSTRACT
Comparisons between Hox genes in different arthropods suggest that the diversity of Antennapedia-class homeotic genes present in modern insects had already arisen before the divergence of insects and crustaceans, probably during the Cambrian. Hox gene duplications are therefore unlikely to have occurred concomitantly with trunk segment diversification in the lineage leading to insects. Available data suggest that domains of homeotic gene expression are also generally conserved among insects, but changes in Hox gene regulation may have played a significant role in segment diversification. Differences that have been documented alter specific aspects of Hox gene regulation within segments and correlate with alterations in segment morphology rather than overt homeotic transformations.
The Drosophila Hox cluster contains several homeobox genes that are not homeotic genes -bicoid, fushi-tarazu and zen. The role of these genes during early development has been studied in some detail. It appears to be without parallel among the vertebrate Hox genes. No well conserved homologues of these genes have been found in other taxa, suggesting that they are evolving faster than the homeotic genes. Relatively divergent Antp-class genes isolated from other insects are probably homologues of fushi-tarazu, but these are almost unrecognisable outside of their homeodomains, and have accumulated approximately 10 times as many changes in their homeodomains as have homeotic genes in the same comparisons. They show conserved patterns of expression in the nervous system, but not during early development.
A class act: conservation of homeodomain protein functions
Authors: Manak J. Robert , Scott Matthew P. 
Published: April 2021

ABSTRACT
Dramatic successes in identifying vertebrate homeobox genes closely related to their insect relatives have led to the recognition of classes within the homeodomain superfamily. To what extent are the homeodomain protein classes dedicated to specific functions during development? Although information on vertebrate gene functions is limited, existing evidence from mice and nematodes clearly supports conservation of function for the Hox genes. Less compelling, but still remarkable, is the conservation of other homeobox gene classes and of regulators of homeotic gene expression and function. It is too soon to say whether the cases of conservation are unique and exceptional, or the beginning of a profoundly unified view of gene regulation in animal development. In any case, new questions are raised by the data: how can the differences between mammals and insects be compatible with conservation of homeobox gene function? Did the evolution of animal form involve a proliferation of new homeodomain proteins, new modes of regulation of existing gene types, or new relationships with target genes, or is evolutionary change largely the province of other classes of genes? In this review, we summarize what is known about conservation of homeobox gene function.
The relation of the two blastomeres to the polar lobe in Dentalium
Authors: Verdonk N. H. 
Published: April 2021

ABSTRACT
Experiments on the influence of the polar lobe on the development of molluscs have shown that after removal of the polar lobe cleavage is radially symmetrical and indications of bilateral symmetry do not appear (Wilson, 1904: Dentalium;Clement, 1952: Ilyanassa). In normal development the polar lobe fuses with one of the two cells of the trefoil stage, and this cell becomes the posterior side of the embryo.
Albumen absorption during chick embryogenesis
Authors: Carinci P. , Manzoli-Guidotti L. 
Published: April 2021

ABSTRACT
In birds albumen represents a substantial part of the reserve material for their embryological development (Romanoff & Romanoff, 1949). In Gallus gallus albumen proteins form 50 % of non-incubated egg protein content (Romanoff & Romanoff, 1949). During incubation such material is absorbed and utilized, to a great extent, for the synthesis of embryonal proteins (Fiske & Boyden, 1926; Rupe & Farmer, 1955). It is not yet well understood how these processes (albumen absorption and utilization for the energetic and nutritional needs of the embryo) take place. The present available data indicate that the amount of albumen solids begins to diminish starting from 11 to 12 days of incubation (Romanoff & Romanoff, 1933; Rupe & Farmer, 1955). From 13 to 14 days, after the sero-amniotic connexion perforates, the protein content of the amniotic fluid shows a marked increase because of the passage of albumen (Needham, 1931 ; Romanoff, 1960). During the same development period albumen proteins can be recovered, in large amounts, in the yolk (Saito, Martin & Cook, 1965; Carinci, Wegelin & Manzoli-Guidotti, 1966).
Observations on CBA-p/CBA-T6T6 mouse chimeras
Authors: Mystkowska Ewa T. , Tarkowski Andrzej K. 
Published: April 2021

ABSTRACT
A considerable amount of information bearing upon mouse chimeras obtained experimentally by fusion of cleaving eggs has already been accumulated (Tarkowski, 1961, 1963, 1964a, b, 1965; Mintz, 1962a, b, 1964a, b, 1965a, b, 1967). Direct and indisputable proofs of the chimerism of the individuals produced were obtained by establishing that two types of pigment cells were present in the outer layer of the retina (Tarkowski, 1963,1964a) and in the coat (Mintz, 1965a, b, 1967). The cell composition of other organs and tissues has not as yet been investigated. True hermaphroditism in some of the animals obtained was also accepted as an indirect proof of chimerism (Tarkowski, 1961, 1963, 1964b; Mintz, 1965b) but the postulate of these individuals being six-chromosome chimeras has not as yet been directly confirmed by karyological research.
Etude experimentale de Forganogenèse du poumon: nature et spécificité des interactions épithélio-mésenchymateuses
Authors: Dameron Fl. 
Published: April 2021

ABSTRACT
On sait que Forganogenèse pulmonaire (Dameron, 1961a, b) s’effectue seulement lorsque les deux constituants de l’ébauche, épithélium bronchique et mésenchyme pulmonaire, sont associés. Les interactions qui s’exercent entre les deux tissus sont indispensables pour la croissance et la différenciation de l’épithélium.
Le rôle de l’épiblaste dans la chondrogénèse du bourgeon de membre chez la Souris
Authors: Milaire J. , Mulnard J. 
Published: April 2021

ABSTRACT
Les facteurs qui contrôlent la morphogénèse et la croissance des bourgeons de membres ont suscité un intérêt considérable au cours de ces vingt dernières années. Tous les travaux qui y ont été consacrés se basent sur des techniques d’expérimentation directe appliquée in vivo aux bourgeons de membres du poulet, ou, dans une moindre mesure, à ceux du xénope. Leurs résultats ont fait l’objet de plusieurs articles de synthèse qui nous autorisent à n’en rappeler ici que les points essentiels (Zwilling, 1961; Tschumi, 1962; Amprino, 1965). Dès qu’il prend naissance aux dépens de la pariétopleure, le mésoblaste présomptif des membres acquiert la faculté d’induire, dans son feuillet de revêtement, la formation d’un épaississement marginal connu sous le nom de cape épiblastique apicale. Aussitôt constituée, cette structure stimule à son tour la croissance du mésoblaste sous-jacent et assure ainsi la mise en place des matériaux destinés à former les segments de plus en plus distaux du membre. Dans ce jeu d’influences réciproques, c’est le mésoblaste qui détient le rôle principal et spécifique. Non seulement il induit la formation d’une cape apicale, mais durant toute la morphogénèse il continue d’émettre, vers la périphérie du bourgeon, un facteur diffusible assurant le maintien de l’intégrité structurale et fonctionnelle de la crête épiblastique. Les informations dont nous disposons concernant le rôle de l’épiblaste sont beaucoup moins précises. Il paraît bien s’agir d’une induction non spécifique stimulant la prolifération du mésoblaste sous-jacent, mais on ignore tout des modalités de cette influence et de ses répercussions éventuelles sur les capacités d’histodifférenciation du mésoblaste.