bluuebunny/crossref_metadata_2025_split huggingface dataset:
Developmental regulatory mechanisms in the evolution of insect diversity
Authors: Carroll Sean B. 
Published: April 2021

ABSTRACT
The major architectural differences between most Arthropod classes and orders involve variations in the number, type and pattern of body appendages. We have utilized the emerging knowledge of appendage formation in fruit flies to begin to address the developmental and genetic basis of morphological diversity among insects. Butterflies, for example, differ from fruit flies in possessing larval abdominal limbs, two pairs of adult wings, and a sophisticated system of wing color pattern formation. We have found that the genetic bases for these three major morphological features involve differences between flies and butterflies at three levels of genetic regulation during development.
First, we show that the presence of abdominal limbs in butterflies is associated with striking changes in the regulation of specific homeotic genes in the abdominal segments of the butterfly embryo. Second, we suggest that the twowinged state of the fruit fly and the distinct pattern of the butterfly hindwing are the consequence of many accumulated changes in the target genes regulated by the Ultra-bithorax homeotic gene. And finally, we demonstrate that a new genetic program, involving many of the same genes that specify the conserved global patterning coordinates of fruit fly and butterfly wings, has been superimposed onto the butterfly wing to create their unique color patterning system. These findings demonstrate how morphological diversity arises from the different ways in which conserved sets of regulatory genes are deployed during development.
Domain organizations of extracellular matrix proteins and their evolution
Authors: Engel Jürgen , Efimov Vladimir P. , Maurer Patrik 
Published: April 2021

ABSTRACT
The astonishing diversity in structure and function of extracellular matrix (ECM) proteins originates from different combinations of domains. These are defined as autonomously folding units. Many domains are similar in sequence and structure indicating common ancestry. Evo lutionarily homologous domains are, however, often func tionally very different, which renders function prediction from sequence difficult. Related and different domains are frequently repeated in the same or in different polypeptide chains. Common assembly domains include α-helical coiled-coil domains and collagen triple helices. Other domains have been shown to be involved in assembly to other ECM proteins or in cell binding and cell signalling. The function of most of the domains, however, remains to be elucidated. ECM proteins are rather recent ‘inventions’, and most occur either in plants or mammals but not in both. Their creation by domain shuffling involved a number of different mechanisms at the DNA level in which introns played an important role.
Etude ultrastructurale de Fectoblaste chez l’embryon d’Urodèle normal ou traité par l’urée
Authors: Gallera J. , Baud C. A. 
Published: April 2021

ABSTRACT
A preliminary description is given of the submicroscopic texture of the yolk platelets and of the membrane which surrounds them, as also of that of the hyaloplasm.
The ultrastructure of the cytoplasm of neurectoblast cells and of ventral epiblast cells from young neurulas is characterized by an obvious dorso-ventral orientation of the constituents (hyaloplasm and yolk platelets).
After treatment with urea these cells no longer show this orientation, and they then resemble normal ectoblast cells, but of a younger stage, at the beginning of gastrulation.
The modifications of ultrastructure are correlated with modifications of competence. The origin of these morphological and functional modifications is discussed.
Analyse de l’induction neurale chez les Amphibiens au moyen d’organisateurs marqués
Authors: Ficq Adrienne 
Published: April 2021

ABSTRACT
The analysis of neural induction by means of organizers tagged by glycine and orotic acid has demonstrated the migration of radioactive substances during neuralization.
The incorporation of these precursors, both as regards proteins and nucleic acids, is greatest in regions undergoing active morphogenesis. It seems to be particularly intense in the nuclei.
The Effect of Three Antimetabolites on Sea-Urchin Development
Authors: Hörstadius Sven , Gustafson Tryggve 
Published: April 2021

ABSTRACT
The metabolic background for morphogenesis has been the object of intense investigations during the past decades. As an approach to this problem the metabolic effects of the vegetalizing lithium ion and the animalizing thiocyanate ion have been investigated (cf. Lindahl, 1936, and Gustafson, 1952). The studies of antimetabolites (growth-factor analogues) during the last decade have opened pathways for interfering with the embryonic metabolism in a predictable way. Using the antimetabolites it is now possible to get a deeper insight into the relation between metabolic processes and different developmental trends.
Le pouvoir inducteur de l’endoblaste présomptif contenu dans la ligne primitive jeune de Poulet
Authors: Gallera J. , Nicolet G. 
Published: April 2021

ABSTRACT
Dans deux notes publiées en 1964 et 1965, Vakaet conclut que la partie antérieure de la jeune ligne primitive, transplantée à la périphérie de l’aire pelIucide, ne peut induire que le cerveau, tandis que son segment moyen induit exclusivement la formation d’une nouvelle ligne primitive. Pourtant, Gallera (1968) a obtenu, dans quelques cas, l’induction d’un cerveau par le segment moyen de la jeune ligne primitive, si bien que la règle établie par Vakaet n’a pas une valeur aussi absolue qu’il le pense. Nous avons repris ces expériences systématiquement d’une part pour vérifier si la potentialité d’induire le cerveau et celle de provoquer la formation d’un nouveau centre gastruléen sont aussi strictement localisées que l’affirme Vakaet et d’autre part pour voir si la nature de la réponse de redoblaste de l’hôte ne dépend pas en partie de son âge, et, enfin, pour établir le rôle joué dans le processus d’induction par l’endoblaste présomptif contenu dans la ligne primitive.
Immunofluorescence studies on the distribution of mouse uterine epithelial antigen in foetal, immature and adult mice
Authors: Forsberg John-Gunnar , Nord Lennart 
Published: April 2021

ABSTRACT
In an investigation of cellular differentiation processes, it is of great value to be able to study the appearance of specific cell products. Systems permitting this include pancreatic exocrine cells which make zymogen granules and amylase (Grobstein, 1964), the myoblast which produces myosin (Konigsberg, 1965), the chondrocyte which makes chondroitin and chondroitin synthesizing en-zymes (Lash, Glick & Madden, 1964), and the melanocyte which makes melanin (Wilde, 1961). In other cases, such well-defined products are not known or are difficult to obtain and it is therefore necessary to turn to other methods for investigations of specific cell changes. Histochemical methods have been widely used but frequently give unspecific results. Advantages are obtained by using immuno-chemical methods which can demonstrate the appearance of organ- or tissue-specific antigen (Dumonde, 1966). The differentiation of the lens has been extensively studied by immuno-histological methods (for reviews, see Halbert & Manski, 1963; Dumonde, 1966). The appearance of kidney-specific antigens during metanephros differentiation was studied by Lahti & Saxén (1966).
Facial formation in normal and cadmium-treated golden hamsters
Authors: Mulvihill James E. , Gamm Stephen H. , Ferm Vergil H. 
Published: April 2021

ABSTRACT
In the golden hamster the critical days of palatal development occur between days 12 and 14 of gestation. During this period the shelves undergo transposition from vertical positions alongside the tongue to horizontal positions above it, and undergo fusion with each other. Palatal transposition, per se, probably takes place on or about day 12. Present data are in-sufficientto indicate in which direction this occurs. Although epithelial remnants arestill present in the midline of the palate on day 13, they have completely disappeared by day 14, thus signaling the completion of the fusion process. Preosteoblast areas are clearly visible on day 12 but actual ossification is first seen on day 13.
Cadmium apparently has a marked deleterious affect on the head mesoderm of golden hamsters, causing the production of numerous malformations, including unilateral and bilateral cleft lips and palates. It is suggested that the clefts found in cadmium-treated hamsters are due to a mesodermal deficiency rather than to a delay in shelf transposition. Marked abnormalities in cartilage formation and delays in ossification are also described.
The mechanism of action of cadmium—whether directly on the differentiating embryonic tissue, or indirectly through action on the maternal tissues—remains to be elucidated.
The origin and movement of prelung cells in the chick embryo as determined by radioautographic mapping
Authors: Rosenquist Glenn C. 
Published: April 2021

ABSTRACT
The origin of the prelung cells was determined by tracing the movements of [3H]thymidine-labelled grafts excised from medium-streak to 4-somite stage chick embryos and transplanted to the epiblast, streak, and endoderm-mesoderm of similarly staged recipient embryos.
At the medium-streak stage the prelung endoderm cells are in the anterior third of the primitive streak; they shortly begin to migrate anteriorly and laterally into the endoderm layer. They are folded into the gut beginning at about the 4-somite stage, and begin to reach their definitive position in the ventrolateral gut wall at the 10-to 16-somite stage. At the ± 22-somite stage the prelung endoderm begins to burrow into the overlying splanchnic layer of mesoderm, pushing the prelung mesoderm ahead of it.
At the medium-streak stage the prelung mesoderm is in the epi blast (dorsal) layer about half-way to the lateral margin of the area pellucida on either side of the streak, at a level about half-way between the anterior and posterior ends of the streak. From this position the prelung mesoderm migrates medially to the streak and is invaginated into the mesoderm layer at a position about half-way between the anterior and posterior ends of the streak. As a section of the dorsal mesentery, it migrates anteriorly and laterally from the streak into the splanchnic mesoderm lateral to the somites. From the head process stage to the early somite stages, the prelung mesoderm is located posterior to the prelung endoderm. The prelung mesoderm continues to migrate with the splanchnic mesoderm into the mesentery dorsal to the heart, where it invests the prelung endoderm after the 16-to 19-somite stage. Beginning at about the 22-somite stage, the prelung endoderm penetrates the prelung mesoderm and the bilateral bronchi are formed.
Interactions morphogènes au cours de l’histogenèse du corpuscule de Herbst, étudiées à l’aide de transplantations hétérochrones
Authors: Saxod Raymond 
Published: April 2021

ABSTRACT
Morphogenetic interactions during the histogenesis of Herbst’s corpuscle, as studied by heterochronic transplantations
Duck embryo frontal buds or bill fragments have been transplanted to the frontal bud or limb bud of early duck embryo hosts. Results show that : Somato-sensory nerve endings are able to participate in corpuscle histogenesis as soon as they reach 14 days of incubation.However, corpuscle histogenesis can take place only in dermis that is older than 20 days of incubation.The time at which the corpuscles form in a graft of a given age is independent of the total duration of graft innervation.
The results, which demonstrate the existence of morphogenetic interactions between the dermal mesenchyme and the nerve endings, are discussed in connexion with what is known about the origin of Herbst’s corpuscle and the role of nerve and cutaneous tissue in its development. A schematic model is proposed for the morphogenetic sequence of Herbst’s corpuscle.
Experimental study of the formation of the bulboventricular loop in the chick
Authors: Castro-Quezada Alfredo , Nadal-Ginard Bernardo , De La Cruz María V. 
Published: April 2021

ABSTRACT
The formation of the normal bulboventricular loop (convex to the right) and the inverted loop (convex to the left) produced by the Lepori technique in chick embryos was studied. The development of the loops was recorded by means of diagrams, photographs and microscopic time-lapse photography. Electron-microscope studies were also made. The normal loop was studied by means of labelling and removal experiments on the heart tube. The results demonstrated that the fusion of both cardiac primordia is made in stage 9— in the mid-line of the embryo and that the first asymmetry of the heart tube appears in stage 10. The truncus region developed in situ directed towards the right after the fusion of both cardiac primordia, and in this region the electron-microscope study demonstrated a gradient of caudo-cephalic differentiation. In stage 10 the left caudal groove is the prospective interventricular groove, but the right caudal groove is not the right atrioventricular groove as had been stated by others. The asymmetric incorporation of both primordia begins in stage 11 —, when the curvature of the loop is already developing. In the removal experiments it was evident that the different portions of the cardiac tube in situ are orientated in space independently of the whole of the loop.
The formation of the experimentally inverted loop is a mirror-image of the normal loop and appears to be originated through mechanic traction of the cardiac tube by the left splachnopleure and not by a faster displacement of the right cardiac primordia.
Uterine protease activities and lysis of the blastocyst covering in the rabbit
Authors: Kirchner C. 
Published: April 2021

ABSTRACT
Protease activity in rabbit uterine secretion and blastocyst between 5 days 18 hours and 7 days 18 hours after mating was studied histologically and electrophoretically by film gelatin lysis. At definite times after the beginning of implantation, the uterine secretion contains two and the blastocyst covering at least one protease, all with different electrophoretic mobility. Digestion of the blastocyst covering begins on the seventh day post coitum in the area of the embryonic disc. The function of the proteases, origin of the blastocyst protease, and possible activation mechanisms of these enzymes are discussed.
The development of rabbit eggs in the ligated oviduct and their viability after re-transfer to recipient rabbits
Authors: Adams C. E. 
Published: April 2021

ABSTRACT
The development of fertilized rabbit eggs trapped in the oviduct by ligation was examined at 84, 96, 108 and 120 h p.c. in ten animals, five of which were superovulated. Out of 210 eggs recovered, only two failed to develop into early blastocysts. The proportion of blastocysts undergoing some expansion increased from 66% at 84 h to 100% from 96 h onwards, when a high proportion, 66-89%, had ruptured zonae pellucidae. The viability of the blastocysts was assessed by transfer to the uteri of recipient rabbits, in which the proportion developing to term fell from 62% at 84 h to 3% at 108 h.
A total of 643, 2- and 4-cell eggs recovered 30 hp.c. was transferred to the ligated oviducts of oestrous, early or mid-luteal does for periods of 24, 48 or 72 h. Development to the early blastocyst stage appeared to be faster in the luteal phase than in oestrous does. Of the eggs recovered after either 48 h or 72 h, 20-40% and 3-17% respectively were capable of developing to term. In general, the less advanced blastocysts survived better.
Three hundred and twenty-one 60 h morulae were transferred to the ligated oviducts of oestrous or mid-luteal does for 24,48 or 60 h. Neither the rate of egg development nor viability was significantly affected by the endocrine status of the temporary recipient. The proportions of eggs developing to term after transfer to recipients were 50%, 20% and 0%.
It is concluded that the rabbit egg cannot develop beyond the early blastocyst stage in the oviduct, irrespective of the host’s endocrine status. If development is interrupted, the life-span of the blastocyst is very short. The rabbit blastocyst requires to undergo almost continuous development to differentiate normally.
Le système nerveux périphérique crânien de l’embryon humain de 9 mm
Authors: Masy par Simone 
Published: April 2021

ABSTRACT
With the help of silver impregnation, an accurate description of the distribution of the cranial nerves of a 9-mm. human embryo is given. The earlier description by Streeter (1908) appears to be incomplete. Numerous anastomoses have been found between the oculomotor and the ophthalmic nerves, between the fifth and the seventh, between the ninth and the tenth, and between the tenth, eleventh, and twelfth nerves. Collateral branches of the various nerves are described. Placodal contributions are found to the olfactory and the acoustic nerves. Cranial autonomic ganglia have not been observed.
In vitro studies on the control of trophoblast outgrowth in the mouse
Authors: Jenkinson E. J. , Wilson I. B. 
Published: April 2021

ABSTRACT
When placed in serum-free medium on reconstituted collagen surfaces re-implantation mouse embryos are capable of producing characteristic trophoblast outgrowths. Previously this pattern of differentiation has been considered to be essentially dependent on the presence of serum macromolecules. Such activity is expressed only at the late blastocyst stage and is qualitatively different from the adhesive interactions between blastomeres earlier in development. The development of the properties responsible for outgrowth is intrinsic to the blastocyst, being independent of stimulation by exposure either to the uterine environment or to whole serum. The significance of these observations related to implantation control in vivo is discussed.
Genetic effects on the timing of early development in the mouse
Authors: Mclaren Anne , Bowman Patricia 
Published: April 2021

ABSTRACTOn the 4th day of gestation, embryos were recovered from mice of the C57BL, RIII, JU, C3H and Q strains, and cell counts were carried out. Significant differences between strains were seen, both in the percentage of embryos which had reached the blastocyst stage, and in the mean number of cells per embryo. C57BL embryos had most cells, and C3H embryos fewest. Examination of earlier stages of C57BL and C3H development showed that the proportionate difference in cell number remained constant, so that the difference involved the time at which cleavage began, and not the rate of cleavage. Activation of the eggs and the formation of pronuclei also occurred earlier in C57BL than in C3H females. The difference in cell number between C57BL and C3H embryos did not depend on a difference in time of mating, nor on the genotype of the male, since reciprocal crosses were similar to the maternal strain. The difference was maintained in culture from the two-cell stage.
A re-examination of two skeletal mutants of the mouse, vestigial-tail (rt) and congenital hydrocephalus (ch)
Authors: Grüneberg H. , Wickramaratne G. A. De S. 
Published: April 2021

ABSTRACT
The development of two skeletal mutants in the mouse has been re-investigated. In vestigial-tail (vt), a simple syndrome is traceable to an anomaly of the primitive streak. In congenital hydrocephalus (ch), the complicated events have been followed to a level at which the most fundamental gene action detected (or, more accurately, postulated) is no longer demonstrable by conventional histological methods. It involves the mesenchyme and some of its direct derivatives (meninges, skeletal blastemata, mesonephros), but also organs of different origin (nasal glands, ureteric bud, certain ganglia) for which the mesenchyme is the environment. Failure of the meningeal mesenchyme to form the subarachnoid drainage system for the cerebrospinal fluid leads to hydrocephalus which, by essentially mechanical means, is responsible for a multitude of subordinated effects.
Effects of cytochalasin B on meiosis and development of fertilized and activated eggs of Sabellaria alveolata L. (Polychaete Annelid)
Authors: Peaucellier G. , Guerrier P. , Bergerard J. 
Published: April 2021

ABSTRACT
Unfertilized, fertilized and activated eggs of Sabellaria alveolata were submitted to cytochalasin B concentrations ranging from 0·1 to 20 μg/ml. Their behaviour was studied either in vivo or in acetocarmine squash preparations. Polar body extrusion, cytokinesis and polar lobe formation are completely inhibited by cytochalasin B concentrations as low as 0·3–0·5 μg/ml. Caryotype determinations demonstrate that chromosomal meiotic and mitotic processes are not affected by the drug. Thus, polyploid embryos usually developed from fertilized eggs whilst they did not from activated ones. This is related to the contrasting behaviour of meiotic and cleavage centres. While the latter duplicates at each cycle, the former cannot replicate at the end of meiosis. This leads to an abortive monastral stage even if inhibition of polar body extrusion has provided the egg with two or four centres. These observations suggest the existence of an internal mechanism regulating the number of effective centrioles at the end of meiosis. They demonstrate also that the main cause of developmental failure in activated eggs cannot be related to ploidy. Eggs treated throughout meiosis with moderate drug concentrations developed into swimming larvae. However, frequent developmental abnormalities affecting lobe dependent structures were obtained even if polar lobe formation was unimpaired. This suggests either that cytochalasin B has irreversibly affected some decisive cortical element or that previously described activating processes, which begin with polar lobe formation, are actually exerted on specific materials segregated during meiosis.
Embryonic defects in Drosophila eggs after partial u.v. irradiation at different wavelengths
Authors: Bownes Mary , Kalthoff Klaus 
Published: April 2021

ABSTRACT
Drosophila eggs at nuclear multiplication or blastoderm stages were regionally irradiated with monochromatic u.v. Twenty-four hours after irradiation, the results were classified as normal larvae, undifferentiated eggs, or defective embryos; the latter were subdivided into embryos with anterior or posterior defects, or embryos without anterior and posterior specificity. The irradiation of anterior (posterior) egg regions and the occurrence of anterior (posterior) defects were strongly correlated. These correlations were found using eggs of both stages. The size of the irradiated area did not obviously influence the types of defect.
Dose-response curves were established irradiating anterior quarters of eggs at 245, 265, 285, or 305 nm wavelength. The frequency of embryonic defects increased with increasing u.v. doses, whereas the dosages applied did not increase the frequency of undifferentiated eggs over the control level. In eggs during nuclear multiplication 285 nm radiation was most effective in producing embryonic defects. After blastoderm formation, the efficiency of irradiation was generally increased but similar at all wavelengths employed. The induction of embryonic defects was photoreversible after u.v.-irradiation at the blastoderm stage. The data reported also include transmittance spectra of chorion and egg membrane preparations from Droso-phila eggs.