bluuebunny/crossref_metadata_2025_split huggingface dataset:
Distribution of Membrane‐Associated Calcium in Fertilized Sea Urchin Eggs during Mitosis*
Authors: ŌHARA TAKANE , SATO HIDEMI 
Published: January 2005

The distribution of membrane‐associated calcium in dividing sea urchin eggs was examined with chlortetracycline as a fluorescent chelate probe. The fluorescence of bound chlortetracycline in fertilized eggs was initially evenly distributed, but began to gather around the nucleus in prophase, and formed a dumb‐bell shaped condensation enclosing the mitotic apparatus by metaphase. During anaphase and telophase, the fluorescence was observed in kinetochore‐to‐pole regions of the spindle, with little fluorescence in the interkinetochore region. The astral regions showed intense fluorescence. The distribution of the chlortetracycline‐fluorescence coincided with that of ER‐like membranes seen in electron micrographs. The distribution of the fluorescence was obscure and the birefringence of spindles disappeared on perfusion on perfusion of the cells in metaphase with 1 mM tetracaine, which is known to displace membrane‐bound calcium.These results suggest that intracellular free calcium ions are sequestered in the membrane system associated with the mitotic apparatus during mitosis.
Changes in the Cell Surface Level of GP126 during Development of Dictyostelium discoideum
Authors: CHADWICK C. M. 
Published: January 2005

The developmental regulation of the vegetative cohesion molecule, gp 126, has been monitored in the cellular slime mould Dictyostelium discoideum. As judged by immunoprecipitation using an anti‐vegetative cell, cohesion blocking antibody, gp126 persisted until at least the grex stage of development although a decline in the level of the molecule was observed thereafter. Further, after the grex stage, cells showed an increasing loss of ability to absorb the cohesion‐blocking effect of an anti‐vegetative cell Fab. Therefore, the decline of gp 126 could be ascribed to a loss from the cell surface. By radio‐iodination of vegetative cells followed by liquid‐scintillation counting of gp 126, developmental‐regulation could be determined quantitatively.At the grex stage of development, whole aggregates were embedded in wax. Longitudinal sections were then stained with a monospecific anti‐gp 126 Fab, followed by a fluorescent sheep anti‐rabbit IgG. Fluorescence was observed only at the tip (the prestalk) region, thereby showing that gp 126 is a prestalk marker.To confirm the above result, grexes were dissociated and cells were separated into prespore and prestalk populations on a gradient of Percoll. Prestalk but not prespore cells were able to absorb the cohesion‐blocking effect of an anti‐vegetative cell Fab.To examine the biosynthesis of gp 126, cells were pulsed with radioactive glucosamine, mannose or acetate. The pattern of incorporation of radioactivity suggested that the de novo synthesis of gp 126 ceases upon commencement of development.
Half‐Life of Histone H4 mRNA in Xenopus laevis Embryonic Cells at Different Stages
Authors: ATSUCHI YASUO , TASHIRO KOSUKE , FU YUCHANG , SHIOKAWA KOICHIRO 
Published: January 2005

By Northern blotting methods we have recently found that the relative amount of histone H4 mRNA per Xenopus embryo is constant during cleavage, doubles during the gastrula stage, then decreases at the neurula stage to the level slightly lower than that of the cleavage‐embryo. At each developmental stage, the level of mRNA will depend on three parameters: amount of maternal mRNA remaining, rate of the synthesis of the mRNA and rate of the decay of the mRNA. In the present experiment, we compared rates of the decay of H4 mRNA in Xenopus embryonic cells at different stages by pulse‐chase experiments with actinomycin D as an inhibitor of transcription.Under the conditions used, the half‐life of H4 mRNA was estimated to be 90, 80, and 100 min, for the late blastula, late gastrula and neurula stages, respectively. The decay of H4 mRNA with a half‐life of 90 min at the late blastula stage predicts exhaustion of most of maternal H4 mRNA by the early gastruia stage. The slightly longer half‐life of H4 mRNA in neurula than in late gastrula cells suggests that H4 mRNA is more stable in neurula cells than in late gastrula cells, and therefore, the large decrease in the level of H4 mRNA observed at the neurula stage does not depend on the increase in the turnover‐rate of H4 mRNA. Probably, neurula cells synthesize less H4 mRNA than late gastrula cells but utilize it for longer time.
Early Reciprocal Interactions between Ectoderm and Chordamesoderm: Statistical Evaluation of Classical Embryological Experiments
Authors: LEYHAUSEN CLAUDIA 
Published: January 2005

Embryos of the urodele Ambystoma mexicanum were used in time set experiments for the analysis of ectoderm‐chrodamesoderm interactions in “primary embryonic induction”. The influence of chordamesoderm‐age (CM‐age), ectoderm‐age (CM‐age), ectoderm‐mass (E‐mass) on differentiation processes were investigated. The results revealed that early interactions exist, which, however, seem to be dominated by the ectoderm in various respect: a) the segregations of the CNS is due to the autonomous change in ectoderm competence phases; b) based on the temporal sequence of competence phases, influences are exerted by the ecto‐neuroderm which support the chordamesoderm in its self‐differentiation capability to chorda and other mesodermal tissues. Consequently, reciprocal impulses from these newly differentiated tissues are warranted (feedback to ectoderm); c) co‐ordination of the cranialization effect and corresponding ectodermal competence phase is achieved; d) the inductive efficiency of the chordamesoderm is strongly supported.Three statistical tests (regression, correlation, information analyses) were conducted (dependant variables: quality and quantity of the differentiated structures; independant variables: experimental factors). All three tests equally rendered statistical significance for the following order of decreasing importance the experimental factors play in induction and differentiation processes: E‐age, E‐mass, CM‐age.
Structural Changes of Yolk Platelets and Related Organelles during Development of the Newt Embryo
Authors: KOMAZAKI SHINJI , ASASHIMA MAKOTO 
Published: January 2005

Structural changes in yolk platelets and related organelles in the cytoplasm of the presumptive ectodermal region up to the stage of gastrulation were studied by light and electron microscopies using full‐grown oocytes, mature eggs descending the oviduct and embryos of the newt, Cynops pyrrhogaster. Yolk platelets with a superficial layer are first observed in mature eggs descending the oviduct. During the cleavage and early morula stages, the superficial layer increases in thickness and the main bodies become more slender. The superficial layer decreases in thickness in the blastula stage, and many yolk platelets lose this layer in the gastrula stage.The amount of rough‐surfaced endoplasmic reticulum (r‐ER) increases rapidly in the morula stage, while Golgi complexes gradually increase in number between the cleavage and gastrula stages. In the cleavage and early morula stages, most of the r‐ER is closely adherent to yolk platelets and is associated with several mitochondria. Two types of free vesicles, large (0.5–4.0 μm diameter) and small (0.15–0.3 μm diameter), were seen in abundance from the early morula stage to the early gastrula stages.Changes in the structure of yolk platelets are discussed in relation to changes in other cytoplsmic organelles.
Analysis In Vitro of Capacity of Fetal Fat Pad to Support Mammary Gland Embryogenesis
Authors: INAGUMA YUTAKA , NISHI YOSHIMI , SAKAKURA TERUYO , KUSAKABE MORIAKI , HOSICK HOWARD L. 
Published: January 2005

Fourteen‐day fetal mammary fat pad precursor tissue (FP) has the capacity to support various fetal epithelia allowing them to accomplish their characteristic development in vivo, without their own mesenchyme (1). This capacity decreases with age of fetal fat pad and is lost postnatally. To analyse the molecular mechanism of such interaction, a method for in vitro duplication of organogenesis is necessary. In the present paper, a co‐culture system of fetal epithelium with prospective mammary fat pad is described. The explanted mammary epithelium started budding, then grew out forming branched mammary ducts with end buds. Ultrastructurally, the developing ductal structures exhibited the typical mammary gland morphogenesis. 3H‐Thymidine incorportion assessed by autoradiography showed that the mammary gland morphogenesis in vitro was due to the proliferation of epithelial cells, not merely to a change of the shape of the epithelium. This supportive capacity of 14‐day FP also decreased with aging; explanted mammary epithelium did not grow into 17‐day FP. When insoluble, non‐living biomatrix was used in place of living FP the epithelium grew into the matrix but the resulting structures lacked characteristic morphology of epithelium on living fetal FP. The difference of capacity between 14‐day and 17‐day tissues was also lost.
Studies on Unequal Cleavage in Sea Urchins III. Micromere Formation under Compression
Authors: DAN KATSUMA 
Published: January 2005

When sea urchin embryos at 2‐cell stage are flattered between agar plates, the direction of cleavage is rotated by 90° in each division in reference to the preceding cleavage and no micromere is formed. But under this condition, micromeres are formed in 2 cases; 1) When the egg axis is parallel to the plane of flattening, 2 micromeres are formed on one side of a square 16‐cell stage. 2) when the egg axis is perpendicular to the plane, 4 micromeres are formed at the center of the square.When put into a groove, a string of 4 cells is formed showing that the spindle direction is further deflected by the groove. In the following 16‐cell stage in the groove, which consists of 2 layers of 8 cells, cases with 2 micromeres on one side and 4 micromeres at the center are still found. If the 2‐cell stage is introduced into a groove after the formation of mitotic apparatus, the spindle direction can no longer be changed and the 4‐cell stage becomes like 4 pancakes stuck in 2 layers, indicating that 2 asters are holding the ends of a spindle in fixed positions.
A Yolk‐granule Component Acts as an Adhesive Material for Dissociated Gastrula Cells of the Newt, Cynops pyrrhogaster
Authors: KOMAZAKI SHINJI 
Published: January 2005

Yolk granules were collected from full‐grown ovarian oocytes of the newt, Cynops pyrrhogaster, and dissolved in 3% acetic acid or 8 M urea solution. Culture dishes were then coated with either of the yolk‐granule solutions. The yolk‐coated surfaces acted as adhesive substrata for dissociated gastrula cells, which showed active locomotion when spread on the surfaces. Divalent cation was required for cell adhesion and spreading on the yolk‐coated surface. Trypsin and glycosidase digestions of dissociated cells or the yolk‐coated surfaces inhibited cell adhesion and spreading. Addition of concanavalin A to the culture medium inhibited cell spreading on the yolk‐coated surfaces, while high concentration (50 mM) of the saccharides, D‐galactose, D‐lactose and D‐mannose, had a slightly inhibitory effect on cell spreading.Two yolk components (30‐kD and 108‐kD proteins) were isolated from yolk granules and applied to the culture dish surfaces. Surfaces coated with the 30‐kD protein showed strong adhesiveness for dissociated gastrula cells.
Competence as the Main Factor Determining the Size of the Neural Plate
Authors: ALBERS BRIGITTE 
Published: January 2005

A piece of ectoderm was taken from the neural plate area of an early neurula (Ambystoma mexicanum) and replaced by competent gastrula ectoderm. Neural tissue was induced in these transplants, and the amount of neural tissue was used to estimate the spreading of the neural inductive stimulus. Dependence was tested of the amount of neural tissue formed in the transplants on the following factors: distance of the transplant from the dorsal midline of the host, age of the host, age of the transplant. The first two factors had no influence on the results but age of the transplant turned out to be decisive. The distance of the transplant from the midline of the host did not influence the amount of neural tissue found in the transplant, even in transplants out side the normal neural plate area neural differentiation was induced.It is concluded that the spreading of neural induction is not controlled by a gradient but by the loss of neural competence of the ectoderm. A model for the spreading of neural induction is suggested using competence and homoiogentic induction as its main factors.
Pepsinogen Induction in Chick Stomach Epithelia by Reaggregated Proventricular Mesenchymal Cells In Vitro
Authors: TAKIGUCHI KEIKO , YASUGI SADAO , MIZUNO TAKEO 
Published: January 2005

In vitro organ culture system which permits embryonic chick proventriculus (glandular stomach) to synthesize pepsinogen de novo was developed. Explants of the proventricular rudiment were cultured on Millipore filters in Medium 199 with Earle's salts supplemented with 50% 12‐day embryo extract at 38°C in 95% air and 5% CO2.In these culture conditions, pepsinogen, a functional marker protein of proventriculus, was first detected after 3 days of cultivation of 6‐day chick proventricular rudiment. When recombined and cultured with 6‐day proventricular mesenchyme, 6‐day oesophageal, proventricular or gizzard (muscular stomach) epithelium expressed pepsinogen while small intestinal epithelium did not. These results were consistent with the previous results obtained by chorioallantoic membrane (CAM) grafting, and showed that the culture conditions are permissive for pepsinogen expression.When recombined and cultured with reaggregated mesenchymal cells isolated from 6‐day proventricular mesenchymal fragments, both 6‐day proventricular and gizzard epithelia formed glandular structure and expressed pepsinogen. This indicates that the proventricular mesenchymal cells retain the ability to induce morphogenesis and cytodifferentiation of the proventricular epithelium even if the normal organization of proventricular mesenchyme is once destroyed.
The Cell Cycle and Cell Population Kinetics in the Programmed Cell Death in the Limb‐Buds of Normal and 5‐Bromodeoxyuridine‐ Treated Chick Embryos
Authors: TONÉ SHIGENOBU , TANAKA SHOJI , KATO YOSHIHIRO 
Published: January 2005

The cell cycle and cell population kinetics have been analyzed in the interdigital regions of chick limb‐buds during the course of programmed cell death both in normal and the 5‐bromodeoxyuridine (BrdU)‐treated embryos. Our previous study has shown that a single administration of BrdU at day 6 1/3 inhibited the programmed cell death occurring in normal development of limb‐buds.Pulse‐ as well as continuous labelings with tritiated thymidine (3H‐TdR) were used. The results obtained from the analyses made on both normal and experimental embryos have demonstrated the presence of a particular DNA‐synthetic period, around day 6 1/3, closely related to the programmed death occurring on day 7 1/3. In normal embryos, new cell populations, which did not belong to any phases of normal cell cycle, made their appearances in the process of programmed cell death. A possible correlation between programmed cell death and the cell cycle has been discussed in relation to the morphogenesis of limbs in both normal and BrdU‐treated embryos.
Distributions of Actin, Vinculin and Fibronectin in the Duodenum of Developing Chick Embryos: Immunohistochemical Studies at the Light Microscope Level
Authors: NODA SETSUKO , MITSUI TAOAO 
Published: January 2005

Microscopic studies were made on the localizations of three different cytoskeletal proteins, actin, vinculin and fibronectin, in the duodenum of developing chick embryos and chicks by an indirect immuno‐fluorescent staining method with specific antibodies.Topographical changes in the distributions of these three proteins seemed to be related to stages in morphogenesis of the duodenum. In early stages of embryonic development, findings suggested interaction between actin and vinculin in the apical region of epithelial cells and between actin and fibronectin in the basal region of these cells. From this stage, vinculin and fibronectin seemed to be of importance in determination and continuity of the polarity of the duodenal epithelium, and in control of the intracellular arrangement of actin. This relation between actin and vinculin seemed to continue throughout embryogenesis.The main role of actin in epithelial cells seemed to change on day 12 from that of forming constricting bundles for morphogenesis of previllous ridges to that of microfilaments in the microvilli and the terminal web.
Estrogen Responsiveness and the Estrogen Receptor during Development of the Murine Female Reproductive Tract
Authors: TAGUCHI OSAMU , BIGSBY ROBERT M. , CUNHA GERALD R. 
Published: January 2005

The developing uterus, vagina, and cervix of mice whose age ranged from 16 days of gestation to 90 days postnatal were examined for nuclear estrogen receptors (ERs) by autoradiographic and whole cell uptake techniques. ERs were present within mesenchymal cells of these organs throughout the entire period of development and maturation. By contrast, nuclear ER first became detectable by autoradiography in the epithelium of vagina and uterus at 5 and 6 days postnatal, respectively.As a result of administration of the synthetic estrogen, diethylstilbestrol (DES), consecutively from 16 to 18 days of gestation, uterine and vaginal epithelial cell height was increased and epithelial secretory activity was elevated during the first 48 hr of postnatal life. Also, a single does of DES administered on the 2nd day after birth stimulated epithelial proliferation in the uterus as determined by 3H‐thymidine incorporation. These typical estrogenic effects occurred in the absence of nuclear ER within the epithelium. Prenatal DES treatment accelerated the onset of ER activity within the epithelium by 2 to 3 days relative to controls. The possibility that certain effects of estrogen on epithelial differentiation may be mediated indirectly via ER positive mesenchymal cells is discussed.
Differentiation Expression in Blastomeres of Cleavage‐Arrested Embryos of the Ascidian Halocynthia roretzi
Authors: NISHIKATA TAKAHITO , MITA‐MIYAZAWA IZUMI , SATOH NORIYUKI 
Published: January 2005

The question whether two or more different genetic programs are expressed in the common cytoplasm of single blastomeres or the expression of one genetic program somehow excludes expression of the other, was analyzed by assessing the occurrence of a muscle‐specific and two epidermis‐specific antigens in cleavage‐arrested blastomeres in early embryos of the ascidian Halocynthia roretzi. Blastomeres which had been arrested in 1‐ to 4‐cell stages expressed only the epidermis markers. Arrested 8‐cell to 32‐cell embryos produced both epidermis and muscle markers, but each cell expressed only one program of differentiation, even though some possessed the potential to express both. The differentiation expressions followed their cell lineages. These results indicate that at least in this experimental system differentiation markers of the two different cell‐types are expressed exclusively.A distinct order was noticed in expression of the two epidermis markers in a single blastomeres; a marker is always superiorly expressed, whereas the other appears only when the superior marker is expressed.
Regulation of the Dorsal Axial Structures in Cell‐Deficient Embryos of Xenopus laevis
Authors: Yuge Masahiro , Yamana Kiyotaka 
Published: January 2005

To study the regulation of the dorsal axial structures, we removed the right animal dorsal and the right vegetal dorsal cells from an 8‐cell embryo of Xenopus laevis.Most of the right dorsal cell‐deficient embryos developed to normally proportioned tailbud embryos. No detectable delay was observed in their development. Examinations of serial sections revealed that they had restored bilateral symmetry. The cell numbers of the somite and the notochord had recovered to more than 90% and 70%, respectively, those of controls. Since the right dorsal cell‐deficient embryo retained roughly three‐quarters of the prospective region for the somites and half of that for the notochord, respectively, the cell number was more than that expected from the remaining prospective regions. Cell lineage analyses showed that progeny of the right ventral cells had formed almost all of the right dorsal axial structures, which are normally formed by the progeny of the right dorsal cells. However, almost all the notochord cells had been derived from the remaining left dorsal cells.These results indicate that some quantitative aspects of regulation as expressed in terms of the cell number were different between the two tissues examined.
Expression of Neural Antigens in Normal Xenopus Embryos and Induced Explants
Authors: Itoh Keiji , Kubota Hiroshi Y. 
Published: January 2005

Monoclonal antibodies were raised against neural tissues of Xenopus larvae. Three monoclonal antibodies, named NEU‐1, NEU‐3, and NEU‐4, were specific for neural tissue and first bound to neural cells at stage 25 after neural tube formation (NEU‐1 and NEU‐3) or at stage 31 (NEU‐4). These antibodies bound to differentiating neural cells, but not to germinal neuroepithelial cells. NEU‐1 and NEU‐3 recognized antigens in cell bodies as well as neural fibers of neural cells, and these antigens were distributed throughout the central nervous system. NEU‐4 bound to antigens in granular materials in neural cells, and these antigens were present in head and trunk regions but not in the tail region.These three antibodies were used as neural markers in two types of induction experiments, in which 1) the animal pole region and the dorsal blastopore lip from stage‐10 gastrulae were combined, or 2) the animal pole region and the vegetal pole region from stage‐8 blastulae were combined. In both experiments, most conjugated explants expressed the NEU‐1, NEU‐3, and NEU‐4 antigens, although the expression of NEU‐4 antigen was delayed compared with those of the NEU‐1 and NEU‐3 antigens. These results show that these antibodies are useful as markers in neural induction experiments.
Scale Arrangement Pattern in a Lepidopteran Wing. 1. Periodic Cellular Pattern in the Pupal Wing of Pieris rapae
Authors: Yoshida Akihiro , Aoki Kiyoshi 
Published: January 2005

In most species of lepidopteran insects, anteroposterior rows formed by scales are arranged at regular intervals in the adult wing; within each row two kinds of scales are alternately arranged. To investigate the cellular basis for the scale arrangement pattern, we examined cell arrangement in the epidermal monolayer of the pupal wing of a small white cabbage butterfly, Pieris rapae, by scanning electron microscopy and light microscopy.The arrangement of scale precursor cells, closely resembling that of scales in the adult wing, was observed in the wing epidermis of the early pupa. Scale precursor cells are proximodistally elongated and form anteroposterior rows. Within a row two kinds of scale precursor cells are nearly alternately arranged, which is not so precise as the alternation of scales in the adult wing. Individual rows of scale precursor cells are separated by rows of single or double undifferentiated general epidermal cells. Occasionally, arrangement abnormalities occur both in the adult and the pupal wing. The cellular basis for the regular spacing of scale rows is discussed.