bluuebunny/crossref_metadata_2025_split huggingface dataset:
DNA synthesis inhibition, cytotoxicity and their relationship to teratogenesis following administration of a nicotinamide antagonist, aminothiadiazole, to pregnant rats
Authors: Scott William J. , Ritter Edmond J. , Wilson James G. 
Published: April 2021

ABSTRACT
Four groups of Wistar rats were treated with 100 mg/kg aminothiadiazole (ATD) i.p. on day 12 of gestation. The first group was allowed to proceed to day 20, when they were sacrificed and the teratogenic effects analyzed in the surviving fetuses. A second group was given 100 mg/kg nicotinamide (NAM) i.p. simultaneously or at intervals of 4, 8 or 12 h following ATD. Third and fourth groups corresponded to the first and second except that [3H]thymidine was administered and one uterine horn removed for histological study or analysis of DNA synthesis rates. The following observations were made:
ATD proved teratogenic to 90% of the surviving fetuses, causing one or more malformations of organs such as limbs, tail, palate and heart. Nicotinamide was capable of protecting the embryo against ATD teratogenicity. This effect diminished as the interval between ATD and NAM administration lengthened so that by 12 h little protection remained. ATD produced a severe and prolonged inhibition of DNA synthesis, reaching a low of 12% of control level at 17 h and returning to near normal by 38 h. NAM reversed this inhibition of DNA synthesis in proportion to the length of the interval between ATD and NAM administration. ATD produces severe cytotoxicity especially in the limb buds and neural tube. Based on this and earlier studies the hypothesis is proposed that the time of appearance of maximal cell death plays a major role in determining the degree and pattern of forelimb ectrodactyly.
ATP metabolism in cleavage-staged mouse embryos
Authors: Ginsberg L. , Hillman N. 
Published: April 2021

ABSTRACT
Total ATP, ATP/ADP ratios, the rates of synthesis and turnover of ATP, and the level of cyanide inhibition of ATP synthesis were determined for 2-cell, 4-cell, 8-cell, late-morula and late-blastocyst mouse embryos. The results show that from the 2-cell stage to the late-blastocyst stage there are progressive decreases in total ATP and in the ATP/ADP ratios. These are accompanied by increases in the rates of ATP turnover as well as in the percentage of inhibition of ATP synthesis by cyanide. These data are discussed in relation to results from other metabolic studies on mouse cleavage-staged embryos and from studies describing configurational changes in the ultrastructure of mitochondria at these developmental stages. It is postulated that the mitochondrial ultrastructural changes during cleavage reflect differences in the levels of oxidative phosphorylation during specific metabolic steady states.
Elicitation of lens formation from the ‘ventral iris’ epithelium of the newt by a carcinogen, N-methyl-N′-nitro-N-nitrosoguanidine
Authors: Eguchi Goro , Watanabe Kenji 
Published: April 2021

ABSTRACT
A potent carcinogenic compound, N-methyl-N′-nitro-N-nitrosoguanidine (NG), was administered to the lentectomized eyes of the newt, Triturus pyrrhogaster. Supernumerary lenses were formed from the dorsal iris and even from the ventral iris, which never transforms into lens following simple surgical lentectomy or the grafting of isolated iris pieces into lentectomized eyes. After the administration of NG the pigmented epithelial cells of the ventral iris were induced to gain the competence for transformation into lens cells. The induced competence of the iris epithelial cells was stably maintained for at least 12 months. The secondary regeneration of the lens 45 days or 12 months after the primary lentectomy took place at the same positions of the ventral area of the iris where the primary lens regeneration had been induced by NG.
The effects of NG were also confirmed by implanting isolated pieces of iris treated with NG solution into lentectomized eyes. Five implants out of 42 available experiments on the ventral half of the iris were found to be transformed into lens.
Properties of the primary organization field in the embryo ofXenopus laevisV. Regulation after removal of the head organizer, in normal early gastrulae and in those already possessing a second implanted organizer
Authors: Cooke J. 
Published: April 2021

ABSTRACTPatterns of individuation occurring in the primary embryonic axis of Xenopus following excision of the organizer region of the early gastrula are described. In some 70 % of cases the information for induction of the complete head is qualitatively restored by the time of cell determination, giving rise to an essentially normal embryo. In some 40 % of cases a second posterior axis of bilaterality is formed, causing development of a secondary anus, tail-fin and spinal cord, and often somites. The probabilities of twinning in the tailfield and of failure to complete apical regulation (= head formation) are largely independent.After such excision of the head organizer region, a delay of some 3 h in the schedule of visible differentiation in the neurula/tail-bud embryo is commonly incurred, whether or not apical regulation is successful.When the apex is excised from a host embryo which has already contained for some hours a second apex (= head organizer) as described in an earlier paper, that grafted apex then captures a considerably increased territory in the host material, as seen from the size of the individuation field finally caused by it. Such a shift across host cells, of the boundary between fields of positional information due to two organizers, is not seen under any conditions where these are left intact, or where host excision is carried out soon after implanting the donor organizer.In discussing the results and reconciling them with earlier observations, it is shown that they strongly suggest the presence of local polar (i.e. vectorial) properties in the presumptive mesoderm, due to signals from restricted regions which have achieved a special apical state. Repolarization of cells by a new organizer is not very rapid, and may spread decrementally from the source. Data on further delays in development, caused by the presence of the second organizer during regulation in the host apex, suggest that one organizer may act directly on cells elsewhere to delay or prevent the restoration of the apical state there.
Induction d’une queue et de parapodes surnuméraires par déviation de l’intestin chez les Nereidae (Annélides Polychètes)
Authors: Boilly B. 
Published: April 2021

Supernumerary tail and parapodia induction by deviation of the intestine in nereids (Annelida: Polychaetd)Localized ablation of the intestine has been performed on normal and grafted specimens of the two polychaetes Nereis pelagica L. and Perinereis cultrifera G. with the following results: In the absence of the intestine, segments are not regenerated but parapodia grow on the plane of section.A segmented tail arises where the intestine is deviated; the regenerate we obtain in this case is of the ‘aneurogenic’ type and without anal cirri and parapodia.These results suggest that caudal regeneration results from the association of different tissues (intestine and the body wall) whereas the nerve cord exerts an influence upon the organization of the regenerate. Likewise the caudal regeneration of parapodia is the consequence of the juxtaposition of a dorsal and a ventral body wall in the presence of the central nervous system.
Teratogenic activity of methadone hydrochloride in mouse and chick embryos
Authors: Jurand A. 
Published: April 2021

ABSTRACTTeratogenic activity of methadone HCl (Physeptone, Burroughs Wellcome and Co.) was tested on inbred JBT/Jd and outbred Q strain mouse embryos and on chick embryos. 22–24 mg/kg injected subcutaneously on the 9th day of pregnancy caused by the 13th day exencephaly in 56 out of 479 JBT/Jd embryos but after 32 mg/kg only in 1 out of 220 of the Q strain. Some affected JBT/Jd embryos showed also rachischisis in the cervical area.The second abnormality shown by the embryos of both strains is Z-shaped kinkage of the spinal cord.In explanted chick embryos cultured in vitro as well as in embryos treated in ovo metha-done causes non-closure of the neural tube with extensive necrosis of the neural plate cells in the cephalic region.The results of this study indicate that methadone, which is a neutropic drug, has an embryo-toxic activity directed against the developing central nervous system.
Passage of bovine serum albumin from the mother to rabbit blastocysts II. Passage from uterine lumen to blastocyst fluid
Authors: Kulangara Abraham C. , Crutchfield Floy L. 
Published: April 2021

ABSTRACTPassage of bovine serum albumin (BSA) into unimplanted rabbit blastocysts was studied using intravenous or intrauterine injection of the mother and in vitro cultivation of 5-day blastocysts. BSA concentration in blastocyst fluid was measured using a quantitative radial immunodiffusion method and confirmed by double diffusion in agar.Intravenous injection of up to 200 mg/kg body weight produced a mean concentration of 106 μg/ml in uterine fluid and the blastocyst fluid was mostly negative. In vitro cultivation with 1–20 mg BSA/ml resulted in appreciable passage which was confirmed by intra-uterine injection. BSA appeared in blastocyst fluid after 2–3 h of exposure. After 24 h, 0·25–2 ·0μg BSA was accumulated. The highest concentration observed in blastocyst fluid was 338 μg/ml and this was about 1·7 % of the surrounding concentration. Combined with previous results on passage from plasma into uterine fluid, it could be calculated that in 24 h the blastocyst fluid acquired about 0· 08 % of the maternal serum concentration of BSA.The accumulation of BSA by the blastocyst is about half that of rabbit albumin in the same period (5–6 days p.c.), which suggests that the unimplanted blastocyst is capable of discriminating between native and foreign serum albumin.
Parthenogenetic development of mouse embryos in vivo: II. Postimplantation development
Authors: Witkowska Anna 
Published: April 2021

ABSTRACT
CBA-p and CBA-T6T6 females were mated with vasectomized males of A strain and early in the morning the eggs were activated in situ with the electric shock of 30, 40 and 50 V. Females were killed between the 5th and the 10th day of pregnancy and the implantation sites were studied histologically or their content was examined under the dissecting microscope. Of the uterine horns, 43·6% contained at least one implantation and the mean number of implantations per horn was 0·76. Altogether 152 implantations were collected. The implantation rate was twice as high in older females (12 weeks and over) as in young ones (6 –8 weeks). The number of living embryos decreased with every day so that on the 9th and 10th day only 2 out of 86 embryos were alive (2·3%). With one exception all embryos which were alive at the time of examination were retarded in development for approximately 1 day. The most advanced embryo was at the 8-somite stage. Two attempts aimed at increasing the synchrony between the embryos and the uterus at the time of implantation (activation immediately after delayed mating and transfer of 4·5-day embryos to 3·5-day uterus) did not improve the survival of embryos after implantation.
Changes in protein during development of Triturus embryos: I. Contents and syntheses of soluble or basic protein of cell components
Authors: Imoh Hiroshi , Minamidani Tsutomu 
Published: April 2021

ABSTRACT
The present paper reports basic data on DNA content, protein content, and protein synthesis in Triturus pyrrhogaster embryos during development from cleavage to the hatching stage. Except for measurements of DNA and total protein contents, embryos were labeled with sodium carbonate-14C for 10 h and fractionated into embryonic cell components, i.e. cytoplasmic mass, yolk and pigment granules, and nuclei, in a discontinuous density gradient of sucrose. The protein content and the radioactivity incorporated into protein were measured in each fraction. Those fractions combining protein soluble in buffer at pH 8·3 and in 0·25 N-HCl were further studied with polyacrylamide gel electrophoresis.
In the newt embryo, four stages of active DNA increase were observed when cultured at constant temperature; they were gastrula, neurula, late tail-bud, and before-hatching stages. Total protein per embryo decreased from 3 to 2 mg during the development studied. The content of cytoplasmic soluble protein per embryo was low and constant throughout development. Synthesis of the fraction was observed at the earliest stage of development studied though the rate was not high and specific activity of the soluble protein increased during development. Qualitative changes in the newly synthesized protein were observed. With the yolk fraction, synthesis of protein, other than from probable contamination with the cytoplasmic fraction, was not detected and a detailed description was omitted.
Changes were observed at two stages of development in the synthesis of nuclear protein soluble in buffer at pH 8·3, the first at gastrulation and the second at late tail-bud stage. The change at gastrulation seemed to be the start of syntheses of the nuclear soluble proteins, while quantitative enhancement rather than qualitative change was noticed at late tail-bud stage. Most of the nuclear protein soluble in 0·25 N-HCl was histone. The histone content increased in accordance with increase in the DNA content and the rate of DNA accumulation was accompanied by proportionate incorporation of radioactivity into histone. Among histone fractions, unique behaviour of the very lysine-rich histone was observed.
The availability of [14C]sodium carbonate in rough estimations of protein synthesis in embryos and significance of the data obtained have been discussed.
Positional information and pattern regulation in hydra: formation of the foot end
Authors: Hicklin J. , Wolpert L. 
Published: April 2021

ABSTRACT
The time required for foot end formation increases with distance from the foot end. Using lateral grafting it was shown that both the peduncle and basal disc could induce a proximal axis when grafted into the gastric region. The time for foot end determination was shown to be about 4 h at the proximal end of the gastric region and to increase towards the head end. In general the determination of the foot end is similar to that of the head end.
The retinotectal projection from a double-ventral compound eye in Xenopus laevis
Authors: Straznicky K. , Gaze R. M. , Keating M. J. 
Published: April 2021

ABSTRACT
The retinotectal projection was mapped in 22 post-metamorphic Xenopus in which the eye under investigation had been made double-ventral by operation at stage 32. The contralateral retinotectal projection from a double-ventral eye is neither normal nor does it show the type of abnormality predicted from previous work on double-nasal and double-temporal eyes. In the case of double-ventral eyes, the nasal part of the field projection tended to be reduplicated about the horizontal midline and those field positions corresponding to latero-medial rows of electrode positions on the tectum ran ventrodorsally in the field. As the electrode rows on the tectum progressed more caudally, so the corresponding rows of stimulus positions in the field tended to curl in a temporal direction. These observations have been interpreted as indicating that the nasotemporal and dorsoventral polarities of the eye are not irreversibly determined at stage 32 and that the mechanisms generating the nasotemporal and dorsoventral axes of the eye may interact with each other.
The fine structure of the reconstructed neural retina of chick embryos
Authors: Fujisawa H. , Nakamura H. , Chin M. 
Published: April 2021

ABSTRACT
The fine structure of reconstructed neural retina formed from dissociated neural retinal cells of -day-old chick embryos on the chorio-allantoic membrane of chick embryos was examined with the electron microscope.
Three nuclear layers (ganglion cell layer, inner and outer nuclear layers) and two fibrous layers (inner and outer plexiform layers) are found within the reconstructed retina.
Both the outer and the inner limiting membranes of the reconstructed structure are constituted from the processes of differentiated Müller cells.
The ganglion cell layer consists of two types of cell, though a typical ganglion cell with axonal process is not observed. Optic nerve fibres are not formed.
Amacrine cells are recognized within the inner nuclear layer.
Differentiation of the inner segment of the photoreceptor cell occurs, but not of the outer segment.
Synaptic structures are recognized in the inner plexiform layer, but not in the outer plexiform layer.
Influence of extrinsic factors on the development of the bulboventricular loop of the chick embryo
Authors: Del RÍO Jorge Salazar 
Published: April 2021

ABSTRACT
Of several chick culture methods investigated, New’s technique produced the greatest percentage of normal bulboventricular loops.
In embryos with two left cardiogenic areas or with two right cardiogenic areas or with the areas exchanged, the bulboventricular loop develops to the right in the cases in which there is integration. When each of the areas was permitted to be expressed without the other and there was closure of the gut, both areas were expressed according to their intrinsic quality. We believe that in stage 5, the type of loop is not determined.
Genetic and environmental factors determining the morphological maturation of the mouse and its relationship with weight growth
Authors: Garrard G. , Harrison G. A. , Weiner J. S. 
Published: April 2021

ABSTRACTData on the morphological development of inbred and F1 hybrid mice reared at 22·8 °C dry bulb, 17·8 °C wet bulb, and 32·2 °C dry bulb, 26·7 °C wet bulb are presented. Animals were weighed at birth, 1 and 2 weeks of age and at each developmental stage. All animals were examined for the freeing of the ear pinnae, eruption of the lower incisor teeth and perforation of the eye membranes and in addition females were examined for the appearance of the first pair of nipples and for perforation of the outer part of the vagina.Within each environment, but especially at 23 °C, there are genotypically characteristic differences in the ages at maturation of each variable. Though the ages of maturation of the different variables are highly correlated within genotypes, early maturation of one variable is not necessarily associated with the early maturation of others. Reciprocal F1 hybrid differences indicate a maternal effect upon the age of maturation which is more marked at 23 than at 32 °C.Comparisons of the ages at maturation in the two environments showed that the only character to mature earlier at 23 than at 32 °C was pinna freeing. The most marked influence of the 32 °C environment in advancing development was on the appearance of nipples and on vaginal opening. In almost all cases, animals reared at 32 °C were lighter at the time of maturation than those at 23 °C. Hence when allowance was made for environmental differences in body weight the association between an environment at 32 °C and early development was further enhanced. Those animals that were relatively heavy when weighed at the weekly interval prior to maturation matured earlier than the lighter ones, especially at 23 1C, indicating that morphological maturation was closely related to overall growth.Both the within, and between, litter variation in the ages and body weights at maturation of a strain tended to be greater in animals exposed to the higher temperature. In bilaterally distributed characters, asymmetrical maturation was more common at 32 than at 23 °C.
The development of the retino-tectal projection in Xenopus laevis: an autoradiographic and degeneration study
Authors: Scott T.M. 
Published: April 2021

ABSTRACT
The development of the retinotectal projection in Xenopus laevis was studied using degeneration and autoradiographic techniques. At stage 47 only the rostral pole of the tectum receives optic fibres. By stage 50 half of the tectum is innervated and by metamorphosis all of the tectum except for narrow caudal and medial strips contains optic fibre terminals.
Micro-disc electrophoresis of soluble proteins in rabbit blastocysts
Authors: Petzoldt Ulrich 
Published: April 2021

ABSTRACT
Soluble proteins were studied in the developing rabbit blastocyst by using a micro-disc electrophoresis technique. The tissues of the blastocyst (in later stages separated into the embryoblastic and trophoblastic parts) were analysed, and their protein patterns were compared with those of uterine secretion and blastocyst fluid.
A protein pattern with more than 20 protein fractions was found in the tissues of the blastocysts. This protein pattern was quite different from those previously reported in uterine secretion or blastocyst fluid. After cleavage and during early phases of development of blastocysts the protein pattern was changing; from the 5th day p.c. it became fairly homogeneous. The protein patterns of the embryonic and trophoblastic parts of the blastocyst tissues were rather similar.
The origin of the proteins in the blastocyst fluid is discussed.
Origine et evolution des cellules trophoblastiques intra-artérielles, chez le rat: etude autoradiographique
Authors: Legrand C. 
Published: April 2021

ABSTRACT

An autoradiographic study of the origin and development of the intra-arterial trophoblast cells in the rat
The trophoblastic origin of the intra-arterial cells observed in the utero-placental arteries has been demonstrated, in the pregnant rat, by conjoined use of colchicine and tritiated thymidine. The development of these large cells is described. The intra-arterial trophoblast originates from a special placental cell population well segregated from the 10th–11 th day of gestation. Due to their cytophysiological characteristics, these foetal cells belong to the ‘renewing cell population’ described in the adult rat.
La lignée germinale chez les Echinodermes: Origine et évolution des cellules germinales au cours de la régénération de la gonade chez l’étoile de merAsterina gibbosaPenn.
Authors: Huet Michel 
Published: April 2021

ABSTRACTThe germinal Une in Echinodermata: the origin and development of the germinal tissue in the course of gonadal regeneration in the sea-star Asterina Gibbosa PennAfter partial surgical removal of the genital apparatus in an interradial structure, the elements removed regenerate. This regeneration produces a migration of germinal cells from a reserve of gonocytes situated in the aboral sinus. When destroyed by irradiation, the reserve cannot regenerate, though somatic regeneration is still possible. These results seem to indicate that Asterina possesses a germinal line distinct from the somatic line.The developmental level of the germinal tissue in the regenerated gonad conforms to that of gonads which have followed their normal cycle. This development is not related to the existence of a privileged anatomical place in the genital apparatus.
Effects of Nerve Growth Factor from the venom ofVipera russellion sensory and sympathetic ganglia from the embryonic chick in culture
Authors: Charlwood Katharine A. , Griffith Marjorie J. , Lamont Margaret D. , Vernon C. A. , Wilcock Joan C. 
Published: April 2021

ABSTRACTSensory and sympathetic ganglia of embryonic chick were cultured in media in which no growth of fibres occurred, and then transferred to culture conditions favouring the growth of fibres. The effects on fibre outgrowth of having NGF in neither, one or both media were examined quantitatively. It was concluded that the main effect of NGF, under these conditions, is to maintain the viability of the neurons. Subsidiary experiments supporting this view are also reported.