bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of Chick Neuro‐retinal Cells in Culture: Serum Factors Acting between 12 and 20 Days of Culture Influence the Extent of Subsequent Lens Cell Formation
Authors: DE POMERAI D. I. , GALI M. A. H.
Published: January 2005

Embryonic chick neuroretinal cells transdifferentiate into lens cells during culture in media containing foetal calf serum (F). This process is largely inhibited if horse serum plus supplementary glucose (Hg) is substituted for F. This paper explores the effect of medium changeover (from F to Hg or vice versa) on the subsequent appearance of lens‐specific δ‐crystallin. If cultures are changed from Hg to F up to 12 days of culture, δ‐production at 40 days is similar to that for controls maintained in F throughout. Changeovers between 14 and 17 days progressively inhibit subsequent δ production, and after 19 days in Hg, lens transdifferentiation cannot be induced by F. Conversely, if cultures are maintained in F for up to 17 days, a changeover to Hg blocks transdifferentiation, whereas similar transfers performed after 19 days give increased δ production. These results suggest that some retinal cells which will eventually form lens in vitro become so determined between the 12th and 20th days of culture. A mixture of 50% Hg and 50% F medium (FHg) does not support δ production even after 60 days, but in the absence of supplementary glucose (FH), δ appears in considerable amounts by 30 days.
Cellular Heterogeneity in the Late‐onset Form of Hereditary Melanomas in the Xiphophorus Fish Hybrids
Authors: OZATO KENJIRO , WAKAMATSU YUKO
Published: January 2005

The late‐onset form of melanomas occurring in the Xiphophorus, fish hybrids carrying a macro‐melanophore gene Sp was investigated for its cellular heterogeneity. The melanoma tissues were dissociated enzymatically and cultured for a short term. The cultured melanoma cells were characterized according to cell size, cell shape, pigmentation, and response to epinephrine. The melanoma cells were considerably heterogeneous in these phenotypic traits. Various combinations of these heterogeneous cells gave a great heterogeneity to individual melanomas. The stability of the phenotypic traits was followed during the course of tumor growth. Cell size and cell shape were stable, but pigmentation and response to epinephrine varied. The results are discussed in relation to cell differentiation and tumor progression.
Effect of 17β‐Estradiol on Growth of Oocytes in Cultured Ovarian Fragments of the Starfish, Asterina Pectinifera
Authors: TAKAHASHI NOBUAKI , KANATANI HARUO
Published: January 2005

The development of growing oocytes of the starfish, Asterina pectinifera, was divided into five stages according to their histological features. Specimens collected monthly from Rishiri Island throughout a year were used. The effect of 17 β‐estradiol on oocyte growth was investigated. When ovarian fragments taken from April females were cultured in artificial seawater containing Medium 199 and streptomycin sulfate for 3 days, oocytes within such fragments did not show any changes in diameter. However, when similar ovarian fragments were cultured in the presence of 10−5M 17 β‐estradiol, the oocyte diameters increased significantly. It is concluded that 17 β‐estradiol enhances the growth of starfish oocytes in cultured ovarian pieces.
Demonstration of rRNA Synthesis in Pre‐Gastrular Embryos of Xenopus Laevis
Authors: SHIOKAWA K. , MISUMI Y. , YAMANA K.
Published: January 2005

Isolated cells from Xenopus laevis embryos at various developmental stages were incubated with (methyl‐3H) methionine to label newly synthesized RNAs. Methylation of RNAs was studied by analyzing nuclease‐digests of high‐molecular‐weight RNAs by DEAE‐Sephadex column chromatography. Labeled rRNA, mRNA and 4s RNA were distinguished by their characteristic patterns of 2′‐0‐methylation and base‐methylation. It was concluded that rRNA synthesis starts during the mid‐ to late‐blastula stage. This is about 4 hr, or at least 3 cell cycles earlier than the initiation of gastrulation, which was previously considered to be the stage when rRNA synthesis begins.
Non‐Coordinated Synthesis of RNA's in Pre‐Gastrular Embryos of Xenopus Laevis
Authors: SHIOKAWA K. , TASHIRO K. , MISUMI Y. , YAMANA K.
Published: January 2005

The rates of syntheses of 18S and 28S rRNA, 5S RNA, capped mRNA and 4S RNA were determined in isolated cells from pre‐ and post‐gastrular embryos of Xenopus laevis. The rate of rRNA synthesis per nucleolated cell Mas about 0.2 pg/hr, or about 5.5 × 104 molecules/hr at the blastula stage, and this value remained constant in later stages. At the blastula stage, about 30 molecules of 5s RNA, 10 molecules of capped mRNA and 900 molecules of 4S RNA were synthesized per molecule of 18S or 28S rRNA. These values were all greatly reduced during the gastrula stage, and at the neurula stage, one molecule each of 5S RNA and capped mRNA and 10 molecules of 4S RNA were synthesized per molecule of 18S or 28S rRNA.
Quantitative Analysis of Protein Synthesis Altered by Estrogen in Cultured Xenopus Liver Parenchymal Cell
Authors: KAWAHARA AKIRA , SATO KAZUKI , AMANO MINORU
Published: January 2005

Using the primary culture system of male Xenopus laevis hepatocytes consisting of more than 95% parenchymal cells, the effect of estradiol‐17 β (10−6M) on protein synthesis was quantitatively analyzed by 3H‐leucine incorporation kinetics and the estimation of specific radioactivity of newly synthesized secretory protein. The cells in a well defined culture revealed high plating efficiency and very low DNA synthetic activity. The cultured cells could synthesize several secretory proteins containing serum albumin. The pattern of secreted proteins in SDS‐polyacrylamide gel electrophoresis (SDS‐PAGE) did not alter with culture time but secretion rate of protein increased for 7 days, starting on the third day following inoculation. Estradiol added to the culture media extensively induced the synthesis of yolk precursor protein vitellogenin which accounted for 40–50% of the overall secretory protein synthesis and 20–30% of the total protein synthesis on day 7 of estradiol treatment. Ultimately, the total protein synthesis and secretory protein synthesis were stimulated 1.2–1.3 fold and 2.0–2.2 fold, respectively, over those of the control cells cultured in the absence of estradiol. These results indicated that the stimulation of protein synthesis was largely due to vitellogenin production. Such an estradiol‐dependent stimulation of protein synthesis was also detected in the low molecular weight protein(s). On the other hand, albumin synthesis was evidently reduced by estradiol. Thus, estradiol had two different effects on protein synthesis.

The results obtained in this study will be discussed in relation to the findings o in vivo experiments.
Alterations in pH and Serum Concentration have Contrasting Effects on Normal and “Foreign” Pathways of Differentiation in Cultures of Embryonic Chick Neuroretinal Cells
Authors: DE POMERAI D. I. , GALI M. A. H.
Published: January 2005

Nine‐day chicken embryo neuroretinal cells transdifferentiate into both lens and pigment cells after 3–4 weeks when cultured in MEM medium containing 10% foetal calf serum at pH 7.4. At pH 6.8. the appearance of lens crystallins is retarded and cholineacetyltransferase (CAT) activity persists for longer, whereas at pH 8.0 crystallins appear earlier and CAT activity declines more rapidly. Cell survival and culture growth are about 10% lower at pH 6.8 than at pH 8.0. If the concentration of foetal calf serum (FCS) is increased from 10% to 25% (at pH 7.4), cell survival and growth are both promoted, crystallins appear slightly earlier and CAT activity declines more rapidly. Converse effects are observed with 5 % serum, accumulation of crystallins being greatly inhibited and CAT activity prolonged. Crystallin production in cultures with 10% or 25% chicken serum (CS) is much less extensive than in similar FCS cultures, but in cultures with 5 % CS, crystallins appear more rapidly, reaching higher levels than in 5 % FCS cultures. However, the pattern of CAT activity in response to different serum levels is similar for both CS and FCS. This might imply the presence of some factor(s) able to stimulate transdifferentiation in FCS, whereas CS can apparently inhibit this process.
Advances in Rabbit Embryo Culture during Organogenesis
Authors: STOKES P. A. , VARDY P. H. , McBRIDE W. G.
Published: January 2005

Modified rodent embryo culture techniques were used to maintain 10 1/2 day rabbit embryos in vitro for up to 24 hr. In homologous, immediately centrifuged, heat inactivated serum containing 2 μCi/ml 3H‐thymidine, observed status was consistently high at 12 hr but fell thereafter. Liquid scintillation counting and autoradiography revealed rapid uptake of radioactivity during the first 12 hr. The splanchnopleure of the inverted yolk‐sac is only partially vascularised in the rabbit and is thus inadequate as a medium of metabolic exchange in extended culture. Nevertheless, this technique will enable a study of the morphology and biochemistry of teratology in vitro in a sensitive species.
Persistent Nucleoli in Early Postimplantation of Rat Embryos
Authors: TAKEUCHI IKUO K. , TAKEUCHI YOSHIKO K.
Published: January 2005

Ultrastructural changes of the nucleolus in mitotic embryonic ectodermal cells of 7 1/2‐day and 7 2/3‐day rat embryos were examined. It was found that the nucleolus was broken down into small fragments during late prophase and metaphase, and that some of these fragments persisted in the cytoplasm of telophase cell (persistent nucleoli). No interphase embryonic ectodermal cells contained persistent nucleoli. Persistent nucleoli were also found in telophase cells of extraembryonic ectoderm, extraembryonic visceral endoderm and parietal endoderm of the embryos, but they disappeared in interphase cells. Persistent nucleoli in telophase cells tended to decrease in size with embryonic age, and they had almost completely disappeared in neuroectodermal cells of the telencephalon in 14 1/2‐day embryos. They were concluded to be remnants of disappearing nucleoli in embryonic cells that were cycling too rapidly to permit their nucleoli to disappear completely.
Conditions Permitting Solid Tumor Formation of Teratocarcinoma Cells in Allogeneic Mice
Authors: ISHIKAWA TOMOICHI
Published: January 2005

In this report, the growth capacity of murine ascitic teratocarcinomas (embryoid bodies, EBs) was studied in certain strains of allogeneic mice. When EB was intravenously injected into Balb/c mice, various types of tumor colonies were formed with various types of differentiated tissues in the lung, as in the case of syngeneic 129/Sv mice. Tumor colonies in the abdomen of Balb/c and other allogeneic mice formed by the intraperitoneal injection of EB, however, contained merely undifferentiated embryonal carcinoma cells (EC cells) and sometimes some primitive tissues, too. Analysis of lung colonies (LCs) from EBs in Balb/c mice indicated that EC cells are a potent target for being rejected but they can escape this rejection by differentiating into various types of tissues cells.
Increased Potassium Conductance in Rana Follicles after Stimulation by Pituitary Extract
Authors: WEINSTEIN STEVEN P. , MORRILL GENE A. , KOSTELLOW ADELE B.
Published: January 2005

Pituitary gonadotropins are believed to induce the somatic cell portion of the amphibian follicle to synthesize and release progesterone which, in turn, induces the resumption of the meiotic divisions in the follicular oocyte. We report here that pituitary extract, at concentrations that induce ovulation and meiosis, causes a rapid hyperpolarization of the follicular oocyte. A similar hyperpolarization is seen in response to porcine LH but not FSH. Voltage clamp studies indicate that this is due to an increase in follicle K+ conductance. An electrical model of the amphibian follicle suggests that pituitary factors act by increasing the K+ conductance of the oolemma, by increasing the extent of oocyte‐follicle cell ionic coupling, or by increasing the conductance of follicle cell plasma membrane. The conductance change does not occur in the absence of follicle cells, is not mediated by progesterone, and is not necessary for meiotic maturation, per se, but may play a role in processes which accompany or follow maturation.
VII. Decrease in the Rate of Respiration in the Spermatozoa of the Sea Urchin, Hemicentrotus Pulcherrimus, Caused by Long Chain Fatty Acyl‐CoA‐induced Inhibition of the Movement
Authors: FUJIWARA AKIKO , MITA MASATOSHI , HINO AKIYA , HAMASAKI TOSHIKAZU , NAITOH YUTAKA , YASUMASU IKUO
Published: January 2005

Spermatozoa of the sea urchin, Hemicentrotus pulcherrimus, showed marked decrease in respiration, and arrested movement after interaction with the fixed eggs. Immotile spermatozoa that had reacted with fixed eggs contained higher levels of long chain fatty acyl‐CoAs than normal motile spermatozoa. On treatment with carnitine, the immotile spermatozoa became motile again and their intracellular concentrations of long chain fatty acyl‐CoAs decreased. On incubation with anti‐mycin A or CN− for 20 min, the motility of normal spermatozoa decreased gradually but their long chain fatty acyl‐CoA content changed only slightly. The decrease in sperm motility in the latter case was probably due to decrease in the level of ATP, resulting from inhibition of respiration by antimycin A or CN−. The motility of spermatozoa extracted with Triton X‐100 was restored by ATP and their movement was inhibited by long chain fatty acyl‐CoAs, such as myristoly CoA and palmitoyl‐CoA, but was not by short chain fatty acyl‐CoAs, such as acetyl‐CoA, propionyl CoA and butyryl‐CoA. Na‐palmitate, Na‐myristate and CoA did not inhibit the reactivation of extracted spermatozoa by ATP.
Changes in Surface Morphology of Myogenic Cells during the Cell Cycle, Fusion and Myotube Formation
Authors: MASUKO SADAHIKO , ISHIKAWA YUJI
Published: January 2005

The surface morphology of chick myogenic cells during development in cell culture was examined by scanning electron microscopy. Myoblasts at the G1 and S phases of the cell cycle had a relatively smooth surface. In late G2 and mitosis, they had many microvilli and some blebs on their surfaces. Ca2+‐deficient fusion‐arrested myoblasts had a relatively smooth surface. When the cells underwent cell fusion, many microvilli, small spherical protrusions, and some blebs appeared on their surface. In newly formed myotubes, the surface over the nucleus was smooth whereas that over perinuclear regions had many flat excrescences and other surface protrusions. This mosaic appearance of the surface was less prominent in striated myotubes. Scanning electron microscopy combined with fluorescence microscopy using rhodamine‐labeled erabutoxin b revealed that sites of accumulation of acetylcholine receptor had a smooth surface. These results suggest that changes in surface structure occur in association with the cell cycle, fusion and subsequent development of myotubes.
Ultracytochemical Modifications of Surface Carbohydrates in Fertilized Eggs of the Common Carp
Authors: KUDO SHIGEHARU
Published: January 2005

The surface of the plasma membrane of unfertilized and fertilized carp eggs was examined by four cytochemical techniques, colloidal thorium, colloidal iron, ruthenium red and phosphotungstic acid stainings, to determine the carbohydrate moieties. The surface of the plasma membrane of unfertilized eggs stained only with colloidal iron, which was heterogeneously deposited: no deposits were seen on the plasma membrane near overlying cortical alveoli. In fertilized eggs, the membrane was stained by all four methods. These ultracytochemical modifications of the surface of the plasma membrane may be caused by participation of the limiting membranes of secretory organelles, probably by turnover of the inner surface of the limiting membranes. Neuraminidase treatment of fertilized eggs eliminated the deposits of colloidal iron on the surface of the plasma membrane and caused an increase in stainability with ruthenium red. Treatment with neuraminidase or trypsin prevented the staining with phosphotungstic acid.
Changes in Activity of Mitochondrial Enzymes during the Development of Xenopus laevis
Authors: NELSON LENNART , LØVTRUP‐REIN HUGUETTE
Published: January 2005

Changes in activity of mitochondrial enzymes were studied during the embryonic development of Xenopus laevis.

The following enzymes were determined: malate dehydrogenase (MDH), isocitrate dehydrogenase (NAD+‐dependent) (IDH), aspartate aminotransferase (GOT), cytochrome oxidase (COX), succinate dehydrogenase (SDH), rotenone‐insensitive NADH cytochrome c reductase (NADH‐red) and monoamine oxidase (MAO). IDH is constant throughout the period studied. COX and SDH, two enzymes of the inner membrane, are constant in pregastrula stages, and subsequently decrease significantly. MDH and NADH‐red are highly active in the pregastrula stages and decline thereafter, while MAO is undetectable during early development and increases significantly only in the larvae. GOT increases during the cleavage stages, being most active in the gastrula stages, and decreases subsequently.

The results are discussed in the sense of mitochondrial differentiation during the early development of the amphibian embryo.
Homoeotic Gene ETc Controls the Cell Number of Embryonic Ectodermal Layers of Bombyx mori
Authors: SHINOHARA YUKIE , KOGA KATSUMI , SAKAGUCHI BUNGO
Published: January 2005

The formation of segments of Bombyx larvae involves differentiation of legged and legless segments during embryogenesis. Observations by light microscopy of serial sections of developing embryos of Bombyx showed that the cell number of the ectodermal layers increased more rapidly in segments where legs were being extruded than in those where no appendages were formed. In the embryos of a homoeotic mutant for the E‐pseudoallelic locus (about 0.0–VI), ETc/ETc, in which all the abdominal segments were legless, the cell number of the ectodermal layers did not increase as in normal embryos. These findings suggest that the ETc gene controls the cell number of the ectodermal layers in relation to the differentiation of abdominal segments.
Local Degeneration of Cilia and Nuclear Activation during Sexual Reproduction in Paramecium caudatum
Authors: WATANABE TSUYOSHI
Published: January 2005

The correlation between local degeneration of cilia and nuclear activation during chemically induced autogamy in Paramecium caudatum was studied by experimental interruption of autogamy. When the induction of autogamy was interrupted 60 min after the onset of chemical induction, nuclear activation did not occur and ciliary regeneration took place at the deciliated surface. On the contrary, when it was interrupted 3 hr after the onset of induction, nuclear activation was not stopped and no reciliation was observed. At this critical stage, the deciliated zone was seen to extend to the right wall of the gullet. These findings suggest that there is a transition point in activation processes. It is conceivable that in autogamous cells that have gone beyond this transition point all processes of nuclear activation proceed, and that the ability to regenerate cilia is lost by the end of autogamy, even if the stimulus for autogamy is removed.
Response to Sperm Penetration of the Cortex of Eggs of the Fish, Plecoglossus altivelis
Authors: KUDO SHIGEHARU
Published: January 2005

The response of the egg to sperm penetration was examined in eggs of the fish, Plecoglossus altivelis, by scanning electron microscopy. Eggs responded to sperm penetration by forming a fertilization cone at a “sperm entry site”, which is a specialized structure in the egg surface under the micropyle. Within one minute, the fertilization cone showed dramatic morphological changes from its earliest appearance, through full two‐storied growth to its marked recession. The sperm entry site in the egg surface is discussed as a morphologically specialized organ responsible for the entrance of a fertilizing spermatozoon. The morphological characteristics of the egg and sperm are also described.
Optical Recording of the Pacemaking Activity of a Congenital Double‐heart in an Early Chick Embryo
Authors: FUJII SHIROH , SAKAI TETSURO , HIROTA AKIHIKO , KAMINO KOHTARO
Published: January 2005

A congenital double‐hearted chick embryo was found among 16,171 embryos, which was at the 11 somite stage of development. The pacemaking activity of its double heart was monitored simultaneously from 9 different regions by optical methods. The right and left half hearts were tubular, and in both, spontaneous rhythmical action potentials and beating were detected, and differences were detected in their rhythms. Action potentials were also monitored in a malformed embryonic heart formed by partial fusion of the primordia. The results are discussed in relation to genesis of intrinsic pacemaking activity in cardiac primordia and to a spatial gradient of rhythmicity in the early stages of cardiogenesis.
Stimulation of Unfertilized Eggs of the Echiuroid, Urechis unicinctus by Polyamines
Authors: FUJIWARA AKIKO , KUSUNOKI SHINICHIRO , TAZAWA EIGORO , YASUMASU IKUO
Published: January 2005

Unfertilized eggs of the echiuroid, Urechis unicinctus, were activated by polyamines, such as putrescine, spermidine and spermine at concentrations above 10 μM. Fertilization membrane elevated and germinal vesicle disappeared in unfertilized eggs kept for several min in sea water containing these polyamines. Following the addition of these polyamines, a decrease of pH value in the egg suspension, occurred in a similar manner as observed following fertilization. Several sec after the addition of polyamines to the egg suspension, the respiratoy rate increased very slightly and the sensitivity of the respiration to 2, 4‐dinitrophenol, which was lower in unfertilized eggs than in fertilized eggs, became as high as in fertilized ones. Irregular cleavage occurred in the eggs stimulated by polyamines. The incorporation of [3H]‐deoxyadenosine into DNA was initiated by adding polyamines in the unfertilized eggs preloaded with the isotope. The rate of [3H]‐leucine incorporation into protein in the preloaded unfertilized eggs was also enhanced by polyamines, in almost the same manner as observed following fertilization.
Denervation Effects on Limb Regeneration in Postmetamorphic Xenopus laevis
Authors: KURABUCHI SHINGO , INOUE SAKAE
Published: January 2005

The effects of denervation on limb regeneration of postmetamorphic Xenopus laevis in the early to late stages of regeneration were studied. Limbs that were denervated immediately after amputation did not show any signs of regeneration. Moreover regenerating limbs denervated 20, 30, 40 and 60 days after amputation showed significant regression of regenerates. After this regression of regenerates, the regenerative capacity was not restored during a long observation period. Denervation reduced both protein synthesis (3H leucine autoradiography) and mitotic activity of regenerating limbs even in later stages of regeneration. These results on the role of the nerve in limb regeneration of Xenopus were compared with results in Xenopus and urodeles reported previously.
Trifluoperazine‐Sensitive Step during Sea Urchin, Echiuroid and Pelecypod Egg Activation
Authors: MEIJER LAURENT , DUBE FRANÇOIS , GUERRIER PIERRE
Published: January 2005

Trifluoperazine, a calmodulin‐antagonist, is shown to inhibit egg activation by ionophore A 23187 in sea urchin (I50: 43 μM), by trypsin in echiufoids (I50: 22 μM) and by KCl in bivalves (I50: 34 μM). In each case the inhibition could be reversed by washing the eggs and the trifluoperazine‐sensitive period was clearly limited. In Barnea and Urechis, trifluoperazine inhibits calcium uptake. A common trifluoperazine‐sensitive step, possibly involving calmodulin, may thus be shared by a variety of animal groups during egg activation.
Obstruction of Blastodisc Formation by Cytochalasin B in the Zebrafish, Brachydanio rerio
Authors: KATOW HIDEKI
Published: January 2005

The blastodisc formation in the zebrafish, Brachydanio rerio, was obstructed by treatment with 1.0 μg/ml of cytochalasin B (CB), but not by 1.0 μg/ml of colchicine. The cortex in normal eggs contained a meshwork of microfilaments associated with the plasma membrane. The cortex was thicker at the vegetal pole and thinner at the animal pole of the egg. In CB treated eggs the cortex contained masses of microfilaments detached in places from the plasma membrane. Microtubules were never observed in the cortex of eggs with or without CB treatment. These results suggest that ooplasmic segregation, which results in blastodisc formation, is carried out by activity of the cortex, which contains CB sensitive microfilaments.
Fine Structure and Differentiation of the Acrosome‐Like Structure in the Solitary Ascidians, Pyura haustor aud Styela plicata1
Authors: FUKUMOTO MAKOTO
Published: January 2005

An acrosome‐like structure has been recognized at the apex of mature spermatozoa of both Pyura haustor and Styela plicata. The acrosome‐like structure of P. haustor is a slightly depressed ellipsoid, approximately 90 nm × 80 nm × 50 nm, in length, width and height, respectively, while that of S. plicata is an antero‐posteriorly elongated, flattened vesicle, approximately 200 nm × 100 nm × 50 nm, in length, width and height, respectively.

During spermiogenesis, two vesicles (50–80 nm in diameter) are found in a blister at the apex of early spermatids of both species. These vesicles, presumably derived from the Golgi apparatus, contain moderately electron‐dense material. In late spermatids, these two vesicles appear to fuse to form an acrosome‐like structure.

Because of its extremely reduced size and the paucity of its contents, it is unlikely that the acrosome‐like structure of these sperm contain a significant amount of chorion lysin(s). A well developed Golgi apparatus and many Golgi vesicles of various sizes are found in the cytoplasm of spermatids in both P. haustor and S. plicata. It is hypothesized that ascidian spermatozoa contain a poorly developed acrosome, and that the chorion lysin(s) are intercalated into the plasmalemma enclosing the sperm head.
Further Studies on the Developmental Change in Myotrophic Activity of Chicken Serum: Relation between Activity and Transferrin
Authors: KIMURA ICHIRO , OZAWA EIJIRO
Published: January 2005

As an extension of previous studies, we reexamined the developmental change in trophic activity of chicken serum on chicken myogenic cells in vitro and attempted to elucidate it on the basis of possible changes in serum transferrin (Tf), the myotrophic activity of which depends both on its concentration and on the level of its iron‐saturation. The myotrophic activity was found to be low until the second week in ovo, then to increase rather abruptly to a plateau at about the time of hatching, and then to decrease to the adult level. Determination of the concentration and level of iron‐saturation of serum Tf suggested that the change in myotrophic activity was mainly caused by these two parameters, though another factor(s) may also be involved.
A Changing Pattern of the Cell Cycle during the First Two Cleavage Divisions of the Mouse
Authors: DOMON MASAHARU
Published: January 2005

The cell cycles of the early cleavage stages of the mouse were analyzed by examining Feulgen‐stained ova. The period from ovulation to the completion of second cleavage division was investigated. The ova donors were C57BL/6 × DBA/2 female mice, which were hormonally superovulated. To estimate the durations of DNA synthesis and mitotic phases of the cleavage divisions, the ova were pooled into culture medium, and as a function of time, aliquots were removed from the batch of pooled ova. The ova specimens were Feulgen‐stained and classified as the ova nuclei in G1, S, G2 or mitosis by use of a cytophotometric technique and then the durations of these phases were determined by probit analysis.

The pronuclear stage had a generation time of 11 hr, with a G1 phase of 6 hr and a short S phase of 1.7 hr. In contrast the two‐cell stage had a generation time of 18 hr, with a G1 phase of 2 hr and an S phase of 3 hr. The duration of cleavage division also changed; the first cleavage division spanned 3 hr while the second spanned 1 hr.
Intracellular Localization of DNA Polymerases in the Oocyte of Starfish, Asterina pectinifera
Authors: OISHI NOBORU , SHIMADA HIRAKU
Published: January 2005

Oocytes of the starfish, Asterina pectinifera, were separated into karyoplasts and cytoplasts by centrifugation in a sucrose density gradient in the presence of cytochalasin B. More than 90% of the DNA polymerase activity of whole oocytes was recovered in the karyoplasts, and less than 10% in the cytoplasts. DNA polymerase α was specifically localized in karyoplasts. Of the DNA polymerase β activity of whole oocytes, 70–80% was found in the karyoplasts, and about 15% in the cytoplasts. The problem of whether DNA polymerases are localized within germinal vesicles in starfish oocytes is discussed.
Asymmetrical Development of the Gonads in the Embryos and Fry of the Fish, Oryzias celebensis
Authors: HAMAGUCHI SATOSHI
Published: January 2005

The development of the gonad in Oryzias celebensis was studied by light and electron microscopy. The path of PGC‐migration, the time of the sex‐differentiation, and the pattern of germ cell proliferation were almost identical to those in O. latipes. The most conspicuous difference was in the distribution of germ cells after migration. The gonadal anlage in O. celebensis developed only on the right side of the dorsal mesentery, although PGCs were stituated on the both sides of the embryos before migration. The testis retained its unilateral condition throughout development and acquired a unilobed shape. In the female, the right presumptive ovary developed over the mesentery, and the ovary became bilobed. Thereafter, right and left parts of the presumptive ovary fused to develop into a single ovary in the adult fish. The situation appears to be comparable to the gonadal asymmetry in birds, but the present observations suggest that the developmental processes of the asymmetrical gonads in this fish are quite different from those in birds.
Emergence of the Extrachromosomal Circular DNA Complexes as One of the Earliest Signals of Cellular Differentiation in the Early Development of Mouse Embryo
Authors: YAMAGISHI HIDEO , KUNISADA TAKAHIRO , IWAKURA YOICHIRO , NISHIMUNE YOSHITAKE , OGISO YOKO , MATSUSHIRO AIZO
Published: January 2005

A small number of mouse embryos and embryonal carcinoma cells were pressed by mica sheet; then the extruded DNA complexes were adsorbed to mica and processed for electron microscopy. Extrachromosomal circular DNA complexes longer than 1 μm emerged during the compaction process of mouse embryos and during the differentiation of embryonal carcinoma cells induced with retinoic acid. These DNA molecules are discussed as possible products of developmental gene rearrangements occurring in the chromosomal DNA.
Fusion of Spermatozoa with Embryonic Cells and Somatic Cells in the Sea Urchin
Authors: KATO KOICHI H. , IWAIKAWA YUKIO , SUGIYAMA MASAO
Published: January 2005

Spermatozoa can enter the separated blastomeres of 8‐ and 16‐cell stage embryos, the cells of blastulae and even somatic cells of the oesophagus wall of an adult sea urchin, under certain conditions. In the presence of egg jelly solution, the rate of entrance of spermatozoa is remarkably increased. In the case of the blastomere of 8‐cell stage embryos, characteristic cytoplasmic protrusions are formed at the sites of sperm entry, in succession to the formation of the cytoplasmic bulge. These protrusions elongate until 4 min after insemination, and then they retract gradually. The nucleus of penetrated sperm swells and decondenses to form a pronucleus. In most cases, the pronucleus seems to fuse with the preexisting diploid nucleus of the blastomere. When the dissociated oesophagus cells were inseminated, a certain type of the cells was found to fuse with spermatozoa, although the percentage of fused cells was very low.
Morphological Modifications of Oocyte Vitelline Envelope from Bufo arenarum during Different Functional States
Authors: MARIANO MARTA I. , De MARTIN MARTA G. , PISANO ARMANDO
Published: January 2005

The submicroscopic morphology of the vitelline envelope of Bufo arenarum's oocyte change significantly during the maturation and fertilization processes. The morphological changes are related to physiological activity in vivo and can be triggered in vitro by experimental procedures. It is our scope to present the ultrastructure differences of fascicular components of the vitelline envelope in coelomic, “pars recta” conditioned, oviductal, oviposited and fertilized oocytes. Our experimental results indicate that artificial “pars recta” treatment of coelomic oocytes arrange the fascicular components as those of oviposited oocyte, although differences still remain indicating that additional maturation processes take place while the egg pass througth the oviduct. Fertilized or activated oocytes which are refractary to sperm penetration, change the vitelline envelope fascicular components orientation giving a submicroscopical image quite different to those of none fertilized oocytes. These ultrastructural changes define in a clear cut manner the functional states of Bufo arenarum's oocyte.
Studies on the Cytoplasmic Determinant for Muscle Cell Differentiation in Ascidian Embryos: An Attempt at Transplantation of the Myoplasm
Authors: DENO TAKUYA , SATOH NORIYUKI
Published: January 2005

The 8‐cell stage embryos of the ascidian Halocynthia roretzi which had been prevented from undergoing further divisions by continuous treatment with cytochalasin B could develop histospecific muscle acetylcholinesterase in two blastomeres (B4.1 and B4.1 cells). If the cytoplasm of a B4.1 or B4.1 cell was transplanted by microinjection into either an A4.1 or A4.1 cell of recipient embryos and the transplanted embryos were permanently cleavage‐arrested with cytochalasin B, a few eventually developed AChE in three blastomeres instead of in just the two blastomeres found in cleavage‐arrested control embryos. Judging from the relative positions of the blastomeres, the third AChE‐producing cells appeared to be the A4.1 or A4.1 cells injected with the cytoplasm of B4.1 or B4.1. Although the success rate was considerably low, this result might indicate the presence in the cytoplasm of a determinant for the muscle‐specific enzyme development.
Graph‐Theoretical Analysis of Cleavage Pattern: Graph Developmental System and Its Application to Cleavage Pattern of Ascidian Egg
Authors: DOI HIROFUMI
Published: January 2005

The skeletal structure of the embryo is represented by the graph. In the graph, the cells and the connectivities between the cells are reduced to the nodes and edges, respectively. Along cleavage history, the series of graphs is obtained. In this paper I propose a new graph developmental system(GDS) which develops the series of graphs. And I represent and analyze the cleavage pattern of the ascidian egg by GDS. In order to represent it by GDS, at first, the connectivities between the cells are labeled according to the developments of the connectivities at the next time step, and next the cells are labeled. But there are two ways of labeling the cells, then two types of GDS are defined: (1) to label according to the pattern of the connectivities of their descendant cells after two time steps (G‐GDS), (2) to label according to the cell fates (C‐GDS). The C‐GDS of the ascidian egg produces 16 cleavage patterns at 64‐cell stage non‐deterministically. If some labels are distinguished at 16‐cell stage, the C‐GDS becomes deterministic at 64‐cell stage.

GDS will be useful to simulate morphogenesis by the computer graphics.
The Effects of Chemical Animalizing and Vegetalizing Agents and of Cell Dissociation on the Synthesis of 5S RNA and Transfer RNA in Cleaving Sea Urchin Embryos
Authors: O'MELIA ANNE F.
Published: January 2005

The effect of altering normal cell associations and interactions on the synthesis of 5S RNA and transfer RNA (tRNA) was studied in cleaving embryos of the sea urchin, Arbacia punctulata. Cell interactions were altered: (1) by culturing cleaving embryos in the animalizing agent, Evans Blue, and in the vegetalizing agent, Li+ as LiCl and (2) by culturing dissociated cells. Control and experimental embryos each were labeled from 3 h to 6 h post fertilization with [8‐3H]‐guanosine. Sixteen‐cell embryos, whose GTP precursor pools had been preloaded, were dissociated, labeled and cultured under conditions which prevent reaggregation. Quantitative measurements of rates of accumulation of newly synthesized 5S RNA and tRNA showed that these rates are similar in cleaving sea urchin embryos and in corresponding embryos cultured in the presence of Evans Blue and of Li+. In addition, cells dissociated from cleavage embryos and maintained under conditions which prevent reaggregation retained the ability to synthesize 5S RNA and tRNA. These results suggest that normal cell associations and interactions are not necessary for the synthesis of 5S RNA and tRNA to occur in cleaving sea urchin embryos.
Germ Layer Interactions in Pattern Formation of Amphibian Mesoderm during Primary Embryonic Induction
Authors: SUZUKI AKIO S. , MIFUNE YURIKO , KANÉDA TERUO
Published: January 2005

Mesodermal differentiation of dorsal marginal zone (DMZ) before and after invagination was analyzed by a series of combination experiments with different kinds of ectoderm.

Lower DMZ of early gastrula didn't show any axial‐mesoderm (notochord and somitic mesoderm) but lateral mesoderm (mesenchyme, mesothelium, or blood cells) in combinant with non‐competent ventral ectoderm, while combinant with competent ectoderm was found to have well‐differentiated axial‐mesoderm with deutero‐spinocaudal neurals. The axial‐mesoderms have origin in the ectoderm. Uninvaginated DMZ of middle gastrula also showed difference in mesodermal differentiation between competent and non‐competent ectoderms; axial‐mesoderm differentiation was much better in competent than in non‐competent. The axial‐mesoderm originated from the uninvaginated DMZ. Archenteron roof of late gastrula showed regional difference in mesodermal differentiation in both combinants with competent and non‐competent. The present study further demonstrated that there was regionality in promoting effect of induced neurectoderm on axial‐mesoderm differentiation of invaginated archenteron roof.

The present experiments suggest that the cranio‐caudal and dorso‐ventral axis formations of amphibian mesoderm are finally determined by sequential and reciprocal interactions between the mesodermal anlage and the overlying ectoderm. It should be also shown that lower DMZ acts to trigger a series of the sequential interactions during primary embryonic induction.
Ammonia Release by Chum Salmon Eggs at the Initiation of Their Embryonic Development
Authors: YAMAMOTO TADASHI S.
Published: January 2005

We have found that inseminated eggs of the chum salmon, Oncorhynchus keta, actively release alkaline substances when they have been stimulated by deionized water; the pH of the egg suspension prepared in the non‐buffered Salmon‐Ringer solution shifts within at least 1.3 pH units. The nesslerization method and an ammonia gas sensitive electrode measurement reveal that the alkalization of the suspension is partly due to the efflux of ammonia from the stimulated eggs. The increase in the intracellular ammonia level leading to the alkalization of ooplasm may occur at an early stage of the embryonic development. Since the ammonia release is observed also in the eggs stimulated parthenogenetically by deionized water, it can be inferred that the stimulation of the egg triggers a reaction which increases the ammonia level in the ooplasm.

The environmental medium of stimulated eggs contains fairly large amounts of organic compounds. Its UV spectrum shows a peak at 249 nm; the position of the absorption maximum corresponds to that of inosine monophosphate (IMP). This fact suggests that IMP is one of the components of the organic compounds. The presence of IMP in the medium is also shown by thin layer chromatography. The medium contains monosaccharides and peptides. We have explained these results by postulating that an abrupt change in the activity of adenylate deaminase which catalyzes the conversion of adenosine monophosphate to ammonia and IMP occurs at the initiation of the embryonic development in the chum salmon egg.
Mobility of Membrane Lipids and Proteins at the Animal and Vegetal Pole of the Sea Urchin Egg
Authors: PETERS R. , SARDET C. , RICHTER H.‐P.
Published: January 2005

We have compared the mobility of a fluorescent lipid analogue and of fluorescently labeled membrane proteins at the animal and vegetal poles of the egg of the sea urchin Paracentrotus lividus. Translational diffusion coefficients have been measured by fluorescence microphotolysis (“photo‐bleaching”) on the egg which was rotated on its poles. Lipid and protein diffusion coefficients averaged 0.8 μm2/sec and 0.04 μm2/sec, respectively at both animal and vegetal pole of the egg. Substances which were known to animalize (Zn++) or vegetalize (Li+) the sea urchin egg had no significant effect on protein diffusion coefficients.
Electron Microscopic Observations on the Cortical Reaction of the Brittle‐Star Amphipholis kochii Lütken, with Special Reference to its Vitelline Coat Modification as Revealed by the Surface Replica Method
Authors: YAMASHITA MASAKANE
Published: January 2005

This paper describes the fine structural changes of the egg of the brittle‐star Amphipholis kochii Lütken during the cortical reaction. The vitelline coat is 20 nm thick, when Ruthenium Red stain is used, and consists of a dense network of fibers. The cortical granules are large, 1.5–2.0 μm in diameter, and exist in several layers in the egg cortex, unlike the monolayer arrangement found in many other animals. The contents of the cortical granules are clearly distinguished into two components: peripheral fibrous (PF) material and central fibrous (CF) material that consists of two components differing in electron density. The PF material is densely stained by periodic acid‐chromic acid‐silver methenamine stain, while the CF material is stained little if at all by this technique. The vitelline coat and some PF materials form the fertilization membrane, which is about 40 nm thick and consists of three layers; the outer and the inner layer of the fertilization membrane each have a trilaminated structure. The vitelline coat substances are probably located in the upper part of the fertilization membrane. The hyaline layer, 7–8 μm thick, consists mainly of CF materials. These observations on the morphology of the ophiuroid egg are discussed in comparison with those on other echinoderms, especially echinoids and asteroids.
Isolation of an Insulin‐Responsive Preadipose Cell Line and a Mammary Tumor Virus‐Producing, Dome‐Forming Epithelial Cell Line from a Mouse Mammary Tumor
Authors: ENAMI JUMPEI , ENAMI SONOKO , KOGA MUTUYOSI
Published: January 2005

Two functional tissue culture cell lines, MTD and MTF cell lines, have been isolated from a mouse mammary tumor. MTD cells are epithelial and retain the ability to transport fluid leading to the formation of three‐dimensional fluid‐filled multicellular structures called “domes” or “hemicysts”. Another property of MTD cells is the production of murine mammary tumor virus (MTV). Release of MTV into the culture medium was verified by immunological, electrophoretic and enzymatic analyses. Addition of dexamethasone in the culture medium enhanced both the formation of domes and the production of MTV. Thus, MTD cells retain the morphological and functional properties of the original mammary tumor cells.

MTF cells show the fibroblastic morphology in subconfluent cultures. After reaching confluence, however, these cells gradually accumulated triglycerides in the cytoplasm and eventually assumed the morphology of fat cells. This adipose conversion was greatly enhanced by the presence of insulin in the culture medium. The morphological resemblance of adipose‐converted MTF cells to the mammary fat cells suggests that the MTF cell line was derived from the mammary fat pad stroma. These functional cell lines will be useful to study cell differentiation as well as cell‐to‐cell interactions in the mammary gland.
Early Development of Mouse Anterior Pituitary: Role of Mesenchyme
Authors: KUSAKABE MORIAKI , SAKAKURA TERUYO , SANO MASAO , NISHIZUKA YASUAKI
Published: January 2005

Epithelial‐mesenchymal interaction in the early development of the anterior pituitary gland was examined by chronological observations on fetal pituitary epithelium grafted in vivo with and without its own mesenchyme. At 8.5 days of gestation, the RATHKE'S pouch began to evaginate toward the diencephalon. The mesenchymal tissue around the pouch was at first very sparsely scattered, but then condensed, on day 10 becoming visible under a dissecting microscope. When RATHKE'S pouch epithelia from 10‐ and 12‐day fetuses were transplanted alone under the kidney capsule, they proliferated slightly to form cysts, the cells of which differentiated into ACTH‐producing cells, but not into prolactin‐producing cells. Pituitary morphogenesis did not occur. When these epithelia were recombined with homotypic mesenchyme and transplanted, the epithelia proliferated remarkably on one side of the wall of the pouch, resulting in formation of a pars distalis that contained both ACTH‐producing cells and prolactin‐producing cells. Heterotypic mesenchyme, such as lung, dermis and mammary gland mesenchyme, could induce 12‐day epithelium, but not 10‐day epithelium to develop into pars distalis. Thus, fetal pituitary epithelium has the capacity of autodifferentiation into ACTH‐producing cells, not into prolactin‐producing cells, and requires mesenchymal support for development of the pars distalis.
Protein Synthetic Activities during Spermiogenesis in the Sea Urchin: An high Resolution Autoradiographic Study of 3H‐Leucine Incorporation
Authors: NICOTRA ANTONIETTA , ARIZZI MARIO , GALLO PATRIZIA VALENTINA
Published: January 2005

Protein synthetic activity has been studied during spermiogenesis of Paracentrotus lividus by high‐resolution autoradiography using 3H‐leucine as a labeled precursor. Under the adopted experimental conditions 3H‐leucine is incorporated during the whole spermiogenesis period. The early spermatid is the most active stage and it shows labeling over the nucleus, the cytosol and the mitochondria. Nuclear 3H‐leucine incorporation progressively decreases as spermiogenesis proceeds. Cytosol labeling shows similar values at early and intermediate spermatid and it undergoes a considerable decreases at late spermatid. Mitochondrial grain density increases from early to intermediate spermatid and it remains almost constant at late spermatid.

Our results are compared with the data reported for other animal groups and possible functions of the observed protein synthesis are discussed.