bluuebunny/crossref_metadata_2025_split huggingface dataset:
Differentiation of allantoic endoderm implanted into the presumptive digestive area in avian embryos. A study with organ-specific antigens
Authors: Yasugi Sadao 
Published: April 2021

ABSTRACT
Quail allantoic endoderm was implanted into the presumptive digestive-tract area of chick embryos, and the differentiation of the endoderm was examined morphologically and immunocytochemically with antisera against pepsinogens and sucrase. The allantoic endoderm was incorporated into the host digestive organs. It often became continuous with the host endoderm and formed a chimaeric digestive-tract epithelium. It differentiated morphologically into the epithelium of the digestive organ into which it was incorporated, showing the morphological inductive ability in situ of the digestive-tract mesenchyme against the allantoic endoderm. However, the allantoic endoderm did not produce pepsinogens even when it was incorporated into the host proventricular mesenchyme and formed well-developed proventricular glands. This result indicates that the heterotypic morphogenesis of the allantoic endoderm is not necessarily accompanied by the heterotypic cytodifferentiation. In contrast, the anti-sucrase antiserum-reactive cells often differentiated in the allantoic endoderm incorporated into not only the intestine but also other organs. This confirmed our previous observation that the allantoic endoderm has a tendency to differentiate into the intestinal epithelium in the heterologous environment.
Genetic analysis of developmental mechanisms in hydra
Authors: Takano Jun , Sugiyama Tsutomu 
Published: April 2021

ABSTRACT
Chimaeric hydra strains were produced from a normal strain (105) and a naturally-occurring mutant strain (L4) which has a large polyp size, a low budding rate and a high head-inhibition potential. Various properties of the chimaeras were then examined and compared to those of the two parental strains.
Hydra tissue consists of three cell lineages: the ectodermal epithelial, the endodermal epithelial and the interstitial cell lineages. Using the methods recently developed by Marcum & Campbell (1978b) and by Wanek & Campbell (1982), six chimaeric strains were produced which contained six different combinations of the three cell lineages from 105 and L4.
Evidence obtained from the comparison of the chimaeras and their parental strains indicates that the ectodermal epithelial cell lineage in L4 is primarily responsible for the large polyp size and the low budding rate of this strain, whereas the endodermal epithelial cell lineage is largely, and the interstitial cell lineage is also partially, responsible for the high head-inhibition potential in L4. This suggests that the mechanisms determining the occurrence and location of bud formation and the mechanisms determining the inhibition potential levels are not related to each other (cf. Takano & Sugiyama, 1983; Bode & Bode, 1983). Evidence was also obtained which suggests that the levels of the head-activation and head-inhibition potentials in the chimaeras are determined independent of each other, apparently without the cross-catalytic relationship between them assumed in the Gierer-Meinhardt model (Gierer & Meinhardt, 1972; Meinhardt & Gierer, 1974).
Ontogeny of the granulocyte/macrophage progenitor cell (GM-CFC) pools in the beagle
Authors: Nothdurft Wilhelm , Braasch Eckehard , Calvo Wenceslao , Prümmer Otto , Carbonell Felix , Grilli Gualtiero , Fliedner Theodor M. 
Published: April 2021

ABSTRACT
The pattern of development of the granulocyte/macrophage progenitor cell (GM-CFC) pools in the course of canine ontogeny was studied by means of the agar culture technique. Colony formation was stimulated by colony stimulating activity (CSA) in serum from lethally irradiated dogs in combination with erythrocyte-depleted peripheral blood leukocytes from normal adult dogs. The colonies thus obtained in cultures from the different organs were in general large (estimated maximum 50000 cells) and consisted predominantly of mononucleated macrophages, suggesting that, in these studies, a progenitor cell with high proliferative potential (HPP-CFC) has been monitored.
In the yolk sac, a transitory GM-CFC pool became established between day 23 and day 48 of gestation, reaching maximum numbers of approximately 41 × 103 per organ on days 36β7. At the same time the GM-CFC concentration in blood collected from the heart also reached a maximum of about 31 × 103/ml, indicating its carrier function for the migration of GM-CFC. In the liver a quasi-exponential increase in the GM-CFC numbers took place between days 36β7 and days 57 to 59 when a total of about 15·2 × 106 was found but thereafter and up to day 4 post partum the GM-CFC numbers decreased by almost two orders of magnitude. A continuous increase in the GM-CFC numbers was found in the spleen between day 42 of gestation and day 4 post partum when a maximum of 5·l × 106 to 8·7 × 106 was reached. In contrast to the GM-CFC numbers in the liver, the splenic GM-CFC dropped only by 50 % of peak values when the dogs reached adulthood. The bone marrow always had the highest incidence of GM-CFC, the concentration per 106 cells being 18·7 × 103/106 cells on days 45/46, the earliest time point at which cultures could be set up. The absolute GM-CFC numbers in the two femora increased continuously between days 45/46 and day 4 post partum in parallel with the growth of the bones. In the thymus a relatively small population of GM-CFC developed between days 42 and 48 of gestation that was kept quite constant at average numbers between 13 × 103 and 30 × 103 up to day 4 post partum.
Changes in actin distribution during fertilization of the mouse egg
Authors: Maro B. , Johnson M. H. , Pickering S. J. , Flach G. 
Published: April 2021

ABSTRACT
Unfertilized mouse oocytes and eggs 1–8 h after fertilization in vitro were examined at the light microscope level for structural changes, distribution of actin (as assessed by both antiactin antibodies and NBD-phallicidin), surface binding of concanavalin A (Con A) and chromosomal distribution and condensation. The influence of cytochalasin D on these events was also assessed. Changes in actin distribution were associated with rotation of the second anaphase spindle, formation of the second polar body, the events following incorporation of the sperm nucleus, and formation and migration of the pronuclei. Cytochalasin D prevented spindle rotation, polar body formation, pronuclear migration and the restoration of Con A binding over the site of sperm entry and the site of polar body formation, but did not affect sperm fusion and entry, the loss of Con A binding at the site of sperm entry and pronuclear formation.
The differentiation in vitro of the neural crest cells of the mouse embryo
Authors: Ito Kazuo , Takeuchi Takuji 
Published: April 2021

ABSTRACT
A culture method for neural crest cells of mouse embryo is described. Trunk neural tubes were dissected from 9-day mouse embryos and explanted in culture dishes. The developmental potential of mouse neural crest in vitro was shown to be essentially similar to that of avian neural crest. In the mouse, however, melanocytes always appeared in association with the epithelial sheet close to the explant. Neural crest cells surrounding the epithelial sheet, which probably migrated from the neural tubes in the early culture phase, never differentiated into melanocytes. The bimodal behaviour of mouse crest cells seems to be due to the heterogenous potency of the crest cells and the interaction of these cells with the surrounding microenvironment. This culture system is well suited for various experiments including the analysis of gene control on the differentiation of neural crest cells.
Effects of cytochalasin B on the formation of previllous ridges and the appearance of long microvillous-like processes in the organ culture system of chick embryonic intestine
Authors: Noda Setsuko 
Published: April 2021

ABSTRACT
Between 8 and 12 days of incubation the embryonic duodenum serially constructs with relative regularity the previllous ridges upon which the definitive villi later form. The effects of cytochalasin B (CB) on the formation of these previllous ridges of the duodena of developing chick embryos were studied, varying the concentrations and exposure time of CB in the organ culture system. The results were as follows:- (1) CB inhibited the formation of new previllous ridges from the epithelial cell sheets of 8-to 11-day-old embryonic duodena at a cultured time of 24 h. (2) CB treatment blocked or delayed cytokinesis of the epithelial cells and the production of many long microvillous-like processes (long processes) from the surface of the epithelial cells. (3) These long processes elicited by CB contained actin filaments and their appearance was influenced by the developmental stages of embryos and local parts of epithelial cells. (4) With 11-day embryonic duodena, induction of long processes by CB was observed at various concentrations (1 μg/ml–16 μg/ml) and even after short exposure of 15 min. (5) Cytochalasin D (CD) and colchicine were used and long processes were induced by CD but not by colchicine itself. The appearance of long processes depended on the experimental concentration of CB, CD and colchicine.
In normal developments, such long processes appeared and disappeared within a confined area during the formation of previllous ridges (Noda, 1981). This study seemed to provide experimental support for the previous reported suggestion that the long processes might be one of the important factors in the formation of the previllous ridges of chick embryonic duodena.
Histospecific acetylcholinesterase development in the presumptive muscle cells isolated from 16-cell-stage ascidian embryos with respect to the number of DNA replications
Authors: Mita-Miyazawa Izumi , Ikegami Susumu , Satoh Noriyuki 
Published: April 2021

ABSTRACT
The presumptive muscle cells (B5.1 blastomeres) were isolated from 16-cell-stage embryos of the ascidian, Ciona intestinalis. The isolated cells were allowed to divide either twice or three times thereafter. Then further divisions of the cells were continuously inhibited by a simultaneous treatment with aphidicolin (a specific inhibitor of DNA synthesis) and cytochalasin B (an inhibitor of cytokinesis). When development of muscle-specific acetylcholinesterase in these division-arrested progeny cells of B5.1 blastomeres was examined histochemically, the B5.1 blastomeres which had been allowed two further divisions did not produce any detectable acetylcholinesterase activity. Whereas those which had been allowed three further divisions showed the tissue-specific enzyme activity. These results provide further evidence for the presence of a quantal DNA replication cycle for the tissue-specific enzyme development, which is qualitatively different from the other DNA replication cycles.
Influence of Temperature on Rate of Regeneration in the Time-graded Regeneration Field in Planarians
Authors: Agnes  , Brøndsted H. V. 
Published: April 2021

ABSTRACT
The aim of the experiments was to see how different levels in the time-graded head-regeneration field of two species, differing strongly as to the characteristics of the field, might behave at different temperatures. As was expected, regeneration was retarded for all levels by lowering the temperature. Regeneration of heads was retarded relatively more strongly at posterior levels of the field. Some characteristic differences in regeneration rates of the two species were found, leading to certain suggestions as to the possible nature of the field. By lowering the temperature regeneration may be separated into two main components : formation of the blastema and differentiation of the cells. Formation of the blastema is not seriously impeded at temperatures below 5–6° C., whereas the differentiation processes are nearly brought to a stop at these low temperatures. Doubt is therefore cast on the hypothesis of an adaptive value of regenera-tion in view of the fact that several planarian species actually live and reproduce at temperatures well below those necessary for regeneration.
The Association of Mucopolysaccharides with Morphogenesis of the Palate and Other Structures in Mouse Embryos
Authors: Walker Bruce E. 
Published: April 2021

ABSTRACT
Acid mucopolysaccharides have been postulated to occur in the palatine shelves of mouse embryos on the basis of metachromatic staining with toluidine blue (Walker & Fraser, 1956), and this idea has since been supported by results from radioautography with S35 (Larsson, Bostrom, & Carlsoo, 1958). It was not known which structural component of the tissue contained this substance, but, since aldehyde fuchsin-positive material existed in the same area, the possibility was raised that the component was a network of elastic fibres (Walker & Fraser, 1956). The first purpose of the present paper is to describe further histochemical and radioautographic investigations of this problem, supplemented by electron microscopic observations of palatine shelf tissue.
La Métachromasie au bleu de toluidine dans l’œuf d’Artemia salina
Authors: Fautrez par J. , Fautrez-Firlefyn N. 
Published: April 2021

ABSTRACT
Toluidine blue staining of fixed eggs of Artemia salina reveals during vitellogenesis, maturation, and segmentation the presence of metachromatic granules. These granules originate in certain yolk platelets. Scattered throughout the yolk, they show a series of progressive transformations while migrating into the perinuclear plasm, which they reach at the time of copulation of the pronuclei. During the cleavage divisions they are principally located around the asters. New elements continue to be formed within the yolk until the end of cleavage, when metachromatic elements disappear from the egg. Though they have obviously something to do with the rapid succession of mitoses during cleavage, their formation continues nevertheless in virgin females whose eggs are blocked in metaphase of the first maturation division.
The Importance of Mesenchymal Factors in the Differentiation of Chick Epidermis
Authors: Mcloughlin C. B. 
Published: April 2021

ABSTRACT
The normal differentiation in vitro of whole skin from the limb-bud of the 5-day chick embryo is described briefly. Epidermis isolated by tryptic digestion from the 5-day limb-bud and cultivated alone in vitro shows very few mitoses and keratinizes completely within 10 days. Isolated epidermis grown in vitro in a medium containing excess vitamin A fails to keratinize, secretes mucus and sometimes becomes ciliated; mitoses are rare. Isolated epidermis explanted in contact with cell-free intercellular material from the mesenchyme becomes oriented towards it and arranged around it in an epithelial manner. These findings indicate that while the embryonic epidermis can differentiate in the absence of mesenchyme, contact with a basement membrane and the proximity of mesenchyme and its intercellular material are required for the normal growth and functioning of epithelial cells.
Recherche sur la différenciation protéique au cours du développement des Amphibiens
Authors: Denis par H. 
Published: April 2021

ABSTRACT
Saline extracts of embryos of stages 0–37 (Pleurodeles waltii) were subjected to electrophoresis on cellulose acetate. Various embryonic tissues were studied in the same way. A new band appears in the electrophoretic pattern of whole embryos at the onset of gastrulation. Only minor changes can be detected until stage 31. Thereafter, the electrophoretic pattern becomes rapidly more complicated. From stage 0 to stage 31, there is a slow increase of the overall amount of extractable protein per embryo. After stage 31, soluble proteins appear at an increased rate. This acceleration is probably due to the starting of blood circulation. The various embryonic tissues already have a different protein constitution at the beginning of gastrulation. The proteins seem to be distributed in the early gastrula according to a dorso-ventral gradient. Competent ectoderm and neurulating ectoderm contain particular protein bands. From the second part of gastrulation onwards, the protein content of ventral ectoderm is different from that of neural ectoderm. Every embryonic tissue (except endoderm) acquires new protein bands during neurulation. These bands are different in each tissue. The embryo probably has two types of yolk. These two types are not digested at the same time but successively. The first type is probably located in the axial organs. The second type is contained in the endoderm and seems to be digested only after stage 31.
The Action of Various Agents upon the Rabbit Embryo
Authors: Adams C. E. , Hay Mary F. , Lutwak-Mann Cecilia 
Published: April 2021

ABSTRACT
A study was made of the action upon the rabbit embryo of various agents administered to pregnant animals in doses which did not seriously upset maternal health. The pre-implantation blastocyst, examined as a flat mount, was the principal object of study, but observations were also made on ovulation, fertilization, cleavage, nidation, and subsequent phases of pregnancy. To facilitate comparison between embryos from normal and treated animals 5-to 7-day-old blastocysts from untreated animals, grouped according to size, were classified into 6 developmental stages, depending upon the degree of maturity of the embryonic disc. Additional procedures which served to evaluate the condition of blastocysts and their uterine environment were: mitotic counts made in the abembryonic part of the trophoblast, chemical determinations of certain characteristic constituents of blastocyst fluid, and measurement of carbonic anhydrase activity in the endometrium. . The experimental agents comprised hormones, colchicine derivatives, several polyfunctional alkylating compounds, metabolic analogues, a sulphonamide inhibitor of carbonic anhydrase, and substances endowed with teratogenic, hepatotoxic, radiation-protective, and hypoglycaemia-inducing properties; total body exposure to X-rays was also investigated. Results obtained at various stages of pregnancy with the different treatments are described and discussed; several results relating to blastocysts are illustrated by photomicrographs. Among significant general findings emerging from the study are: the speed with which exogenous agents are transmitted to embryos even before uterine attachment; differential drug sensitivity, frequently evident in the pre-implantation blastocysts, as between the embryonic disc and trophoblast, the former usually being more susceptible; and variability in response, both individual and between litters, of the embryos to parenterally administered agents. It is suggested that the blastocyst flat mount preparation could be adapted as a conveniently rapid and simple procedure for the screening of cytostatic and other growth-modifying agents.
Alkaline Phosphatase Activity in the Rat Uterus1
Authors: Prahlad K. V. , Conaway C. H. 
Published: April 2021

ABSTRACT
A comparative study of the distribution of placental scars from the first and second pregnancies in laboratory rats indicated that the most posterior scar of first pregnancy tends to be nearer to the cervix than the most posterior second pregnancy scar (Momberg & Conaway, 1956). Frazer (1955) in an earlier study observed that more embryos implanted in the caudal half of the uterus of the rat than in the cranial half when the embryo number was four or less. Momberg & Conaway (1956) found this difference to be greater when the embryo number was high.
The length of S-phase and G2-phase of epithelial cells is regulated during growth and morphogenesis in Hydra attenuata
Authors: Herrmann Klaus , Berking Stefan 
Published: April 2021

ABSTRACT
Feeding and sectioning of the freshwater polyp hydra generates signals that (1) shorten the G2-phase of epithelial cells and (2) prevent epithelial cells from entering mitosis for a short period of time. The latter effect appears to be mediated by inhibitor I, an endogenous morphogenetically active compound of hydra tissue. At least after feeding, the S-phase is shortened as well.
A probabilistic model of mosaicism based on the histological analysis of chimaeric rat liver
Authors: Iannaccone P. M. , Weinberg W. C. , Berkwits L. 
Published: April 2021

ABSTRACTThe analysis of pattern development in mosaic and chimaeric animals has provided insight into a number of developmental problems. In order to aid the understanding of the dynamics of the development of mosaic tissues, a computer simulation of the generation of a mosaic tissue was created using simple probabilistic decisions. Results of quantitative analysis of the simulated mosaicism were compared with chimaeric liver. Chimaeric animals were produced by morula aggregation between histologically distinguishable strains of congenic rats. The livers of these animals revealed a pattern of patchy mosaicism unrelated to either acinar or lobular architecture of the organ. Independent quantifiable parameters were correlated and compared between the simulation and chimaeric liver tissue. This analysis showed that extensive cell migration is not required to develop finely variegated mosaic tissue and that the patterns of mosaicism observed could have resulted from tissue development in which as few as three reiterated decisions were required. First, the simulation established anlagen of two cell types of various specified proportions with randomly chosen placement. Second, in each generation of the simulation the order in which the cells divided was established randomly. Third, there was a random choice of the direction of placement of the daughter cell. The quantitative relationships between the proportion of cell types, the area of patches and the number of patches per unit area was consistent between the simulation and the chimaeric tissue.
The midblastula cell cycle transition and the character of mesoderm in u.v.-induced nonaxialXenopusdevelopment
Authors: Cooke Jonathan , Smith J. C. 
Published: April 2021

ABSTRACTXenopus embryos (UV embryos) resulting from u.v. (254 nm) irradiation to the vegetal egg hemisphere and thus developing little or no axial pattern (UV5 -Scharf & Gerhart, 1983), have been compared histologically with synchronous normal siblings at each of three stages. In addition, the relative amounts of bloodforming tissue produced in normal and in UV embryos have been studied by Western blotting total protein from larval stages and by immunofluorescence on sections. The observations on midblastulae (around 5000 cells) were aimed at detecting any systematic retardation, due to u.v., of the slowing of the cell cycle that normally commences at the 2-4000 cell stage and makes possible zygotic transcription and the preparation for gastrulation. No such retardation was apparent. Observations on postgastrular stages gave an assessment of the size and character of the population of mesoderm founder cells, in relation to the control, for embryos visibly undergoing entirely nonaxial development. Little deficit in total mesodermal cell number was found, though the entire mesoderm adopted the histological character proper to only some 40 % of that in the normal pattern i.e. trunk lateral plate. Blood-forming capacity appears to be enhanced out of all proportion to the size of the mesoderm as a whole. The results are discussed in terms of the probable nature of the primary positional system for axial pattern and the later mechanisms of mesodermal patterning.