bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interkinetic nuclear migration during the early stages of lens formation in the chicken embryo
Authors: Zwaan Johan , Bryan Phillips R. , Pearce Thomas L. 
Published: April 2021

ABSTRACT
The optic vesicle in the chicken embryo, after growing out sufficiently to establish contact with the overlying ectoderm, adheres very firmly to the latter for a period of 12-15 h (McKeehan, 1951). Within the area of adhesion the surface ectoderm is transformed into a lens placode under influence of the developing retina. Little is known about the biochemical changes involved in this tissue transformation. Langman (1959) and Langman & Maisel (1962) found a cytotoxic effect of lens protein antisera and specific a-crystallin antibodies on presumptive lens cells shortly after induction had started but before the first morphological changes characteristic for the lens placode were visible. They concluded that the synthesis of a-crystallin might be a prerequisite for lens placode formation. Recent studies with the fluorescent antibody technique, however, indicate that the first crystallins are not produced until the very end of the contact period (Zwaan & Ikeda, 1965, 1968; Ikeda & Zwaan, 1966). α-Crystallin appears even later, at about 3-5 days of incubation when the formation of primary lens fibers has progressed far enough almost to obliterate the lens cavity (Ikeda & Zwaan, 1967).
Variation of the lumbar vertebrae of mice at two environmental temperatures
Authors: Munro Kathleen M. H. , Barnett S. A. 
Published: April 2021

ABSTRACT
The house mouse, Mus musculus L., usually has twenty-six presacral vertebrae: these consist of seven cervical, thirteen thoracic and six lumbar vertebrae (Weber, 1950; Deol, 1958; Berry & Searle, 1963; Berry, 1964). The twenty-sixth vertebra is, however, sometimes abnormal, especially among laboratory mice: on one or both sides it may be fused with the sacrum. There are then five typical lumbar vertebrae, instead of six. The proportion of such abnormalities in a population is influenced by genotype, diet and unidentified maternal factors (reviewed by Griineberg, 1963). Evidence is given below that a low environmental temperature can also increase the incidence of ‘sacralization of L6’.
Chondrogenesis in chick embryo somites in vitro
Authors: Ellison M. L. , Ambrose E. J. , Easty G. C. 
Published: April 2021

ABSTRACT
During the embryonic development of vertebral cartilages, cells from the somite mesoderm differentiate into chondrocytes around the spinal cord and notochord. Grafting experiments in amphibian and chick embryos have indicated that the spinal cord and notochord have some influence on this differentiation of somite cells to cartilage (Holtzer & Detwiler, 1953; Watterson, Fowler & Fowler, 1954). Further analysis in vitro has established that, under specified culture conditions, cartilage formation from somites is, in fact, dependent on the presence of either spinal cord and/or notochord or their extracts (Grobstein & Parker, 1954; Grobstein & Holtzer, 1955; Strudel, 1962, 1963; Lash, 1963).
The permeability of the hamster placenta to radioactive cadmium
Authors: Ferm Vergil H. , Hanlon David P. , Urban John 
Published: April 2021

ABSTRACT
Studies on the permeability of the mammalian placenta to teratogenic agents during the early critical stages of embryogenesis have been relatively few. Most of these studies have been done in the pregnant rabbit, in which the unusually large size of the blastocyst makes it possible to obtain samples of blastocyst fluid for analysis. Thus, investigations have been done on the permeability of the rabbit blastocyst wall to trypan blue and other teratogenic azo dyes (Ferm, 1956), changes in blastocyst sugar content following maternal administration of insulin (Curry & Ferm, 1962; Lutwak-Mann, 1962) and the effect of thalido-mide and other agents on the implanting rabbit blastocyst (Lutwak-Mann & Hay, 1962; Hay, 1964; Fabro, Smith & Williams, 1965; Keberle et al. 1965; Fabro, Hague & Smith, 1967).
Etude des ribosomes et du glycogène des gastrules de Xenopus laevis par cytochimie ultrastructurale
Authors: Gansen P. Van , Schram A. 
Published: April 2021

ABSTRACT
Les travaux de J. Brachet et de ses collaborateurs sur le rôle des acides nucléiques dans le développement embryonnaire des Amphibiens ont eu pour hypothèses directrices, ces dernières années (Brachet, 1965, 1967a, b, 1968), que les synthèses protéiniques spécifiques des différentes étapes de la morphogénèse se feraient dans le cytoplasme au niveau des polyribosomes. Les RNA messagers de ces organites existeraient dans l’œuf sous des formes stables qui se démasqueraient au moment de la maturation et assureraient les synthèses protéiniques pendant la segmentation; à partir de la gastrulation, ils seraient synthétisés au contact de DNA chromosomiaux déréprimés de façon différentielle par les territoires cytoplasmiques où ils se trouvent. Au gradient ribosomial animal-végétatif de l’œuf indivis se superposerait ainsi dans les gastrules un gradient polysomial dorso-ventral, ce double gradient étant l’équivalent biochimique des gradients morphogénétiques des embryo-logistes. Cette conception s’appuie actuellement sur un très grand nombre d’expériences faites à l’aide de techniques biochimiques et autoradiographiques (Brachet, 1967b).
Observations on the origin of the ‘germinal cytoplasm’ in Xenopus laevis
Authors: Czołowska Renata 
Published: April 2021

ABSTRACT
The early appearance of the ‘germinal cytoplasm’ and its behaviour during the formation of cells which are thought to represent the primordial germ cells have been described in detail for Rana temporaria by Bounoure (1927, 1934, 1939) and Blackler (1958). These observations were extended to Xenopus laevis (Nieuwkoop, 1956; Nieuwkoop & Faber, 1956; Blackler, 1958), Bufo bufo (Blackler, 1958), (Berardino, 1961), Discoglossus pictus (Gipouloux,1962a) and Rana esculenta (Hammer, cited by Blackler, 1965b).
Ontogenetic changes in hemoglobin synthesis of two strains of Chironomus tentans
Authors: English Darrel S. 
Published: April 2021

ABSTRACT
Differentiating cells can be characterized by the number and types of proteins they produce (Markert, 1963). In man and other organisms the diversity of hemoglobins has been correlated with ontogenetic changes which reflect the alterations of gene activity (Ingram, 1963). Furthermore, the types of proteins produced are generally specific for the species.
Fate of primordial germ cells in the transplanted hind gut of mouse embryos
Authors: Ożdżeński Wacław 
Published: April 2021

ABSTRACT
During normal development of the mouse embryo, primordial germ cells (PGCs) differentiate in the root of the allantois and in the hind region of the embryo, then pass to the hind gut and through the mesentery to reach the germinal ridges (Chiquoine, 1954; Bennett, 1956; Mintz & Russell, 1957; Mintz, 1957; Ożdżeński, 1967). The number of PGCs increases greatly during migration (Chiquoine, 1954; Mintz & Russell, 1957). After penetrating into the gonads PGCs continue to divide mitotically for a certain time, then undergo changes which differ in each sex: the meiotic prophase begins in the ovaries (Brambell, 1927; Borum, 1961), gonial divisions are arrested in the testes and the chromatin in the nuclei of the germ cells undergoes characteristic dispersion. The behaviour of germ cells in the male embryos of the mouse is similar to that described by Clermont & Perey (1957) and Beaumont & Mandl (1963) in the rat.
Chemically stimulated differentiation of post-nodal pieces of chick blastoderms
Authors: Chauhan S. P. S. , Rao K. Vasudeva 
Published: April 2021

ABSTRACT
Earlier studies on the role of sulfhydryl (-SH) groups in morphogenesis have indicated that in chick and amphibian embryos, an -SH-containing substance can act as an inducing stimulus in the action of the primary organizer. Thus, blocking -SH groups by chloroacetophenone (CAP) has specific developmental effects and the inducing capacity of the Hensen’s node is affected (Lakshmi, 1962 a, b). Reversal of the effects of -SH block by cysteine indicated that whatever is blocked by the -SH inhibitor is restored by cysteine (Mulherkar, Rao & Joshi, 1965; Mulherkar, Rao, Joshi & Joshi, 1966). It appears, however, that not all -SH-containing substances can reverse the effect of -SH block by CAP. Thus the teratogenic effects of CAP could not be ameliorated by a subsequent treatment with cysteamine, a decarboxylation product of cysteine, while CAP and cysteamine mixed in equimolar proportions had no effect on development (Rao, 1969). Inhibition of developing neural tissue and of inducing capacity of the organizer may be due to block of -SH groups of proteins or of the -SH in free cysteine and/or glutathione in the inducing tissue. Since the effects of -SH block can be reversed effectively by cysteine and not by cysteamine, it is likely that the action of cysteine in reversing the effects of -SH block is not the restoration of -SH groups. On the other hand, it is quite likely that an inducing stimulus can be given by substances of low molecular weight, probably cysteine or reduced glutathione. Waheed & Mulherkar (1967) have shown that postnodal pieces (PNPs) treated with cysteine and reduced glutathione, when used as organizer grafts, can induce neural tissue and that the grafts are neuralized or differentiate into somites. Thus there is good evidence that -SH-containing substances like cysteine and glutathione have the ability to stimulate differentiation of axial structures. In the present investigation an attempt has been made to study the inductive effects of cysteine and glutathione on post-nodal pieces of the chick embryo.
Les caractères de la segmentation et la détermination de la polarité dorsoventrale dans le développement de quelques Spiralia
Authors: Guerrier Par Pierre 
Published: April 2021

ABSTRACT
C’est une particularité du développement des Spiralia que d’établir une liaison stricte entre la distribution des blastomères dès le début de la segmentation et les principales orientations de l’embryon qui sera produit en fin de compte. Dès le stade IV, on peut reconnaître la direction antéropostérieure, le plan dorsoventral de symétrie et le sens dextre ou sénestre de la segmentation.
Les caractères de la segmentation et la détermination de la polarité dorsoventrale dans le développement de quelques Spiralia
Authors: Guerrier Par Pierre 
Published: April 2021

ABSTRACT
La formation de la polarité dorsoventrale chez les Spiralia a été interprétée par plusieurs auteurs comme l’expression d’une structure préformée dans l’œuf indivis. Des études antérieures (Guerrier, 1970) m’ont amené à rejeter cette conception pour le développement de Limax maximus où les éléments essentiels de la symétrisation s’expriment de manière relativement tardive au cours du développement. Cependant, chez d’autres Spiralia, comme Sabellaria alveolata, le caractère inégal des premières divisions rend la position du plan de symétrie apparente dès le début du développement. Je me suis donc proposé d’examiner si cette espèce présente, pour la détermination de sa polarité dorsoventrale, un mécanisme particulier.
Etude histochimique dé la distribution des sialomucines dans l’oviducte et les gangues muqueuses des ovocytes de Rana pipiens. Comportement dans l’eau des différentes gangues
Authors: Pereda Par Jaime 
Published: April 2021

ABSTRACT
Les recherches histochimiques ont révélé chez les amphibiens divers mucopolysaccharides, situés dans l’oviducte à des niveaux bien définis et dont la topographie est très précise dans les gangues gélatineuses qui entourent les ovocytes (Humphries & Hughes, 1959; Humphries, 1966; Humphries & Workman, 1966; Pereda, 1969).
The role of exogenous heart-RNA in development of the chick embryo cultivated in vitro
Authors: Niu M. C. , Mulherkar L. 
Published: April 2021

ABSTRACT
The physiological effect of fresh calf heart-RNA was studied on the explanted chick blastoderm at the definitive streak stage. It was found that heart-RNA interferes with normal development of the central nervous system, especially forebrain, and of the body axis, but not with normal development of the heart. To analyse this effect further, the untreated and RNA-treated fragments of the antero-lateral blastoderm were investigated by intrablastodermal transplant and in vitro. Approximately 50% of the treated grafts transplanted intrablastodermally developed into heart, but none of the controls. In vitro formation of the heart-like structure was found in 45% of the heart-RNA-treated series as opposed to 20% of the PC saline controls and none of the liver-RNA series. When the explants of the presumptive forebrain were treated with heart-RNA and cultured in isolation in vitro, 11% developed into brain vesicle compared with 76% of the controls. It appears, therefore, that heart-RNA has somehow collaborated with the macromolecules responsible for heart formation but interfered with those responsible for the development of the central nervous system.
The reaction of the mouse blastocyst and its zona pellucida to enzymes in vitro
Authors: Bowman Patricia , Mclaren Anne 
Published: April 2021

ABSTRACT
Mouse blastocysts were cultured for 24 h in the presence of various substances at concentrations as high as possible, consistent with blastocyst survival. Lysis of the zona pellucida was produced by trypsin and pronase, but not by hyaluronidase, collagenase, β-glucuroni-dase, ribonuclease, neuraminidase or oestrogen. This suggests that the zona lysin secreted by the mouse uterus at the time of implantation consists of a proteolytic enzyme.
The developmental endocrinology of the spleen in chick embryos: I. The pars distalis
Authors: Betz T. W. 
Published: April 2021

ABSTRACT
Partial decapitation (‘hypophysectomy’) of the chick embryo significantly reduces body growth by 20 days (stage 46—) of incubation as indicated by body weights, 60 % of normal; the lengths of the toe and tibiotarsus, 80 % and 78 % of normal respectively; and liver growth, 47 % of normal, but the gall bladder was not apparently enlarged. It significantly increases spleen growth to 82 % greater than normal, suppresses or retards white pulp differentiation and splenic vasculogenesis but enhances red pulp development.
A single pars distalis gland placed as a chorioallantoic graft into operated embryos prevents the development of these defects except for liver growth which, while improved, is still subnormal. If the number of grafts is increased by one or two there is no change in the amount of influence on growth and development of the chick embryo. This apparent regulation occurs by some unknown mechanism even in the absence of the hypothalamus.
Thus body and liver growth is normally stimulated by the pars distalis but spleen growth and red pulp differentiation are suppressed even though the gland stimulates splenic white pulp histogenesis. The hypothalamus, epiphysis and pars nervosa (removed by partial decapitation) are not apparently involved in the developmental endocrinology of the spleen in chick embryos.
The in vitro effect of the nerve growth factor on chick embryo spinal ganglia—a light-microscopic evaluation
Authors: Weis Peddrick 
Published: April 2021

ABSTRACT
The effect of the nerve growth factor (NGF) on chick embryo spinal ganglia was studied in the hanging-drop bioassay system by comparison with parallel development in vivo.
The well-differentiated ventrolateral neuroblasts, which in vivo increase 1·33 times in size during the culture period, did not increase in size at all in vitro. Only 65–72% survived to the end of the culture period regardless of the NGF concentration.
The less-differentiated mediodorsal (M-D) neuroblasts, which in vivo increase .1-31 times in size during the culture period, were found to increase equally in vitro if sufficient NGF was present. Such a quantity was greater than that which evoked maximum outgrowth of neurites.
Survival of M-D neuroblasts was also related to NGF concentration but did not equal the in vivo condition even at the highest concentration. The hyperchromatic type of degeneration prevented by high NGF concentrations is that which results in vivo from insufficient peripheral field.
From this and other reports it would appear that the response to NGF seen in vitro is due only to the M-D neuroblasts, and that all biochemical and cytological observations which have been reported would therefore represent conditions within those cells only.
Ontogeny of haemoglobin in the royal penguin Eudyptes chrysolophus schlegeli
Authors: Shaughnessy P. D. 
Published: April 2021

ABSTRACT
Haemoglobins of chicks, yearlings and known-age sub-adults of the royal penguin were investigated by starch-gel electrophoresis at pH 8·6.
Two haemoglobin components were observed in yearlings and sub-adults. These were assumed to be the haemoglobins of adults.
Another three haemoglobin components were observed in 3-week-old chicks.
Tn seven out of eight fledging chicks, these chick haemoglobins had disappeared.
The existence of other haemoglobin components in royal penguin embryos is predicted.
A radioautographic analysis of the migration and fate of cells derived from the occipital somites in the chick embryo with specific reference to the development of the hypoglossal musculature
Authors: Hazelton R. D. 
Published: April 2021

ABSTRACT
The migration pattern and fate of cells of the occipital somites and overlying ectoderm have been described for the chick embryo with particular reference to the development of the hypoglossal musculature.
Tritium-labelled thymidine (0·5–10 μCi per egg) was used as a cell-specific marker. Occipital somites (2–5) with overlying ectoderm were transplanted orthotopically from labelled donor embryos to unlabelled host embryos (Hamburger & Hamilton, stage 9–10). The embryos were incubated, for varying lengths of time (24 h–5 days), sacrificed, sectioned and the migration pattern and fate of the labelled cells determined radioautographically.
It appears that the hypoglossal as well as other hypopharyngeal musculature originates from the occipital somites.
The mesodermal migration pattern extended from the occipital somite region in a ventro-posterior direction to the dorsal surface of the pericardial cavity posterior to the expanded portion of the pharynx. At this position a so-called hypoglossal cord formed on each side which ran anteriorly to the level of the second pharyngeal pouch where it turned medially and together with the cord from the other side entered the pharyngeal area of the embryo. This material apparently forms the intrinsic musculature of the tongue. The mesodermal movements are attributed to differential growth movements of the areas concerned as well as to active cell mutiplication and migration.
Selective embryonic neuronal staining was undertaken to study the relationship between the migrating hypoglossal cord and nerve. The cord preceded the nerve in its migration.
There is an occipital somitic contribution to the primitive meninx, to the endothelial walls of developing blood vessels, possibly to microglial cells and to the cartilage surrounding the notocord.
The occipital ectoderm expands dorso-anteriorly and ventro-laterally. Tn the ventro-lateral position as contact is made with the pharyngeal endoderm a placode is formed which contributes cells to the nodose ganglion of the tenth cranial nerve. There is no other contribution of the ectoderm to the underlying tissues.
Studies on the transmission of hypostome inhibition in hydra
Authors: Wilby Owen K. , Webster Gerald 
Published: April 2021

ABSTRACT
The inhibition of hypostome formation in hydra has been investigated using isolation and transplantation techniques.
The transmission of inhibition does not seem to be polarized; a hypostome situated at the proximal end of the digestive zone can inhibit distal regeneration with no change in regeneration polarity. The time required for the proximal hypostome to establish an effective inhibitory ‘field’ is about 4–7 h. The results confirm that inhibition and polarity are quite separate factors.
The transmission of inhibition by a digestive zone is impaired by treating the region with media containing reduced concentrations of Ca2+ and Mg2+. This treatment has no effect on the inhibitory activity of the hypostome, nor on the resistance of the tissue to inhibition.
The effect of divalent cations on the transmission of inhibition does not seem to be due to an effect on cell adhesion. There is an effect on general cell permeability but this is not temporally correlated with the effect on transmission.
It is suggested that transmission of inhibition is dependent upon contact-mediated intercellular communication, possibly involving functional coupling between cells.
Cartilage anomaly (can); a new mutant gene in the mouse
Authors: Johnson D. R. , Wise Jean M. 
Published: April 2021

ABSTRACT
Cartilage anomaly (symbol can) is a recessive gene in the mouse producing achondroplasia. Abnormal mice die at about 10 days after birth. Light microscopy reveals a systemic deficiency in the cartilaginous matrix. Electron microscopy suggests that the collagen of the matrix is normal and that the mucopolysaccharide component is reduced.
The origin and movements of the hepatogenic cells in the chick embryo as determined by radioauto graphic mapping
Authors: Rosenquist Glenn C. 
Published: April 2021

ABSTRACT
The origin of the prehepatic 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 layer of similarly staged recipient embryos.
Although exact definition of prehepatic areas was not possible because of the small number of grafts placed at each developmental stage, the study showed in general that at the mediumstreak stage, the prehepatic endoderm cells are in the anterior third of the primitive streak; they shortly begin to migrate anteriorly and laterally into the endoderm layer ventral to the precardiac areas of mesoderm. They are in the yolk-sac endoderm at the 2–4-somite stage, and by the 15–17-somite stage are clustered at the anterior intestinal portal. At the 26-somite to early limb-bud stages, the anterior and posterior liver diverticula have formed from these endoderm cells, and some of the branches of the diverticula may have reached the prehepatic mesenchyme, where the two tissues have begun to form cords and sinuses.
At the medium-streak stage, the prehepatic mesoderm is located slightly more than halfway from the anterior to the posterior end of the primitive streak. From this position it migrates anteriorly and laterally into the lateral plate mesoderm, and from the head-process to the 2–4-somite stage it is situated posterior to the prehepatic endoderm and posterior and lateral to the heart-forming portion of the splanchnic layer. By the 15–17-somite stage the prehepatic mesoderm has reached a position in the splanchnic layer of mesoderm which forms the dorsolateral wall of the sinus venosus. By the 26-somite to early limb-bud stage the hepatic diverticula have joined with the hepatic mesenchyme to form the rudimentary cords and sinuses of the liver.