bluuebunny/crossref_metadata_2025_split huggingface dataset:
Differentiation of pulsating regions in genital imaginal discs after culture in Vivo (Drosophila melanogaster)
Authors: Nöthiger Rolf , Oberlander Herbert 
Published: June 2005

AbstractAfter male genital discs of Drosophila melanogaster had been cultured for 8 to 19 days in the abdomens of adult female flies a number of them contained rhythmically pulsating regions. The percentage of discs which pulsated was dependent on the age of the donor larvae, the length of culture time, the presence or absence of ring glands and on the age of the host. The best conditions for the differentiation of pulsating discs were an old disc in a young host to which a ring gland from a mature larva was added.In normal development the genital disc after metamorphosis gives rise to the genital apparatus with morphologically differentiated ejaculatory duct, sperm pump and paragonia (soft parts) which contract rhythmically. In the cultured discs, however, the contractions are not accompanied by morphogenesis.The prospective fate of the pulsating region of a disc is mostly contracting soft parts of the genital apparatus, whereas the non‐contracting area forms mostly chitinous parts (anal plates, claspers, lateral plates). Other discs, e.g. leg discs and wing discs, which in normal development do not form involuntary muscles also do not contract after culture in vivo.It is concluded that the formation of pulsating regions represents a phase in the normal differention of genital discs. Some of the conditions which lead to pulsation are established early in the third instar within the cells which form the pulsating regions. Their full differentiation is influenced by hormones secreted by the ring gland.
Temperature‐induced alterations in hepatocyte structure of rainbow trout (Salmo gairdneri)
Authors: Berlin J. D. , Dean John Mark 
Published: June 2005

AbstractElectron microscopic examination showed that hepatocytes from rainbow trout (Salmo gairdneri) possess abundant amounts of rough endoplasmic reticulum. Particulate materials, presumably synthesized in the endoplasmic reticulum and transported to the Golgi apparatus, were more numerous in hepatocyte Golgi complexes of trout acclimated at 5° C compared to fish acclimated at 18° C. This temperature‐induced structural modification is thought to reflect an increased secretory activity on the part of the hepatic cell as a result of the organism's adaptation to low temperature.
The Source and identity of a regeneration‐inhibiting factor in hydroid polyps
Authors: Davis Lary V. 
Published: June 2005

AbstractIt has been found that cell‐free homogenates of tentacles and hydranths, but not of stems, are capable of inhibiting distal regeneration in Corymorpha palma. The results of several experiments on this species, and on Chlorohydra viridissima, Hydra littoralis, and H. pirardi have indicated that the observed inhibition was caused mainly by a nematocyst toxin, tetramethylammonium.This conclusion is supported by three independent lines of evidence: (1) direct counts of the nematocysts contained in tentacle, hydranth, and stem homogenates has shown that the amount of inhibitory activity is correlated with the number of nematocysts present; (2) tetramethylammonium was found to inhibit distal regeneration in transected polyps; and (3) paper chromatography of acetone extracts has demonstrated the presence of this quaternary ammonium compound in all species examined.
Diploid and haploid hybridization of different populations of the Rana pipiens complex. I. Experiments with females from Mexico
Authors: Moore John A. 
Published: June 2005

AbstractDiploid and androgenetic haploid hybrids have been made with eggs of Rana pipiens from the Mexican locality Oaxaca and sperm from individuals of the pipiens‐complex from nine localities in Mexico and the United States. The diploid hybrids are normal or nearly so when the males are from localities as distant as Florida, Vermont, or Wisconsin. They are very abnormal when the males are from a locality in the nearby Gulf Coast lowlands, San Andres Tuxtla. Haploid hybrids on the other hand are almost always very abnormal. This suggests that there has been considerable evolutionary divergence in the local populations of the pipiens‐complex and that androgenetic hybridization is a useful technique for detecting this divergence. A few experiments with eggs with another Mexican locality, Zamora, are also reported.
Cleavage of sand dollar eggs with altered patterns of new surface formation
Authors: Rappaport R. , Ratner J. H. 
Published: June 2005

AbstractThe normal pattern by which new surface is formed in cleaving echinoderm eggs is incorporated as an intrinsic part of several general theories of cytokinesis. The purpose of this investigation was to determine whether the normal pattern is necessary for cleavage in sand dollar eggs. Denuded Echinarachnius parma eggs become sticky in citrated, calcium‐free synthetic sea water. When such eggs are pressed against clean glass or plastic, the surfaces adhere tightly. Cells were stuck to flat, cylindrical and hemispherical concave surfaces. Cleavage took place despite bilateral constraint of large portions of the surface. Constraint of the polar and subpolar surfaces begun before or at the beginning of division did not prevent cleavage. Only when the surface next to the furrow was held was division slowed or stopped. Normal, extensive polar and subpolar expansion is not a prerequisite for cleavage. An egg can cleave if its furrow can exert sufficient force to overcome the resistance to deformation of the surface outside the furrow. No preliminary step in which local areas are induced to weaken or relax appears necessary.
Analysis of the effects of neutron radiation on developing Triturus embryos
Authors: Suzuki Akio 
Published: June 2005

AbstractTriturus pyrrhogaster embryos at various stages of development were exposed to neutron radiation, and the effects were studied externally and microscopically. For an analysis of the abnormality in the nervous system produced by the irradiation, the difference in neutron‐sensitivity between the presumptive neural ectoderm and the chordamesoderm was also investigated in vitro.Neutron‐sensitivity descreased from the cleavage stage to the tail‐bud stage; in the latter no effect was observed. Rather high frequency of abnormality was observed in mid‐blastula and early gastrula stages. The abnormalities consisted of microcephalia, acephalia, cyclopia, axial distortion, and edema. The nervous system in particular was very sensitive to neutron radiation.The irradiated presumptive neural ectoderm wrapping non‐irradiated chordamesoderm underwent cytoloysis in vitro and no differentiation occurred in it, while the irradiated chordamesoderm wrapped in the non‐irradiated ectoderm was never affected and retained its inducing and self‐differentiation ability. The results suggest that the irradiated and damaged cells release a cytotoxic agent.
Shedding of the zona pellucida by the rat blastocyst
Authors: Dickmann Z. 
Published: June 2005

AbstractIt is known that rat blastocysts shed their zonae pellucidae during the afternoon of day 5 of pregnancy. The aim of the present study was to determine whether one can detect any morphological changes in the zonae before, during, and after shedding. From 74 rats killed between 11:00 and 19:30 hours on day 5 pregnancy, 711 blastocysts were recovered: 407 were zona‐encased, 293 were zonafree, and 11 were half‐way out of the zona. Preshedding changes were observed in the zonae of 34 of the zona encased blastocysts. The changes were confined to the regions of the embryonic and abembryonic poles. It was concluded that the blastocyst can escape from its zona by way of either the embryonic or the abembryonic pole. The entire process of zona shedding seems to be very rapid, since only 45 blastocysts (i.e., 34 exhibiting preshedding changes and 11 being half‐way out of the zona), out of the 711 recovered, were observed during the process of shedding. Theoretically, for every zona‐free blastocyst, an empty zona should have been recovered. However, the 293 zona‐free blastocysts recovered were matched by only seven empty zonae. The reason for the rapid disappearance of the zona after shedding was not determined.
Nature of induced persistent vaginal cornification in mice. II. Effect of estradiol and testosterone on vaginal epithelium of mice of different ages
Authors: Kimura T. , Nandi S. , Deome K. B. 
Published: June 2005

AbstractImmature female mice of the BALB/c strain were treated with 25 m̈g/day of estradiol or testosterone for five days, beginning at various ages. Ovary‐independent persistent vaginal cornification was obtained only when the treatment was started within 24 hours after birth, although some irreversible hyperplasia of the epithelium was observed in mice treated with estradiol beginning at three days of age. Ovary‐dependent persistent vaginal estrus occurred when treatment was begun at ten days or earlier with estradiol, and at seven days or earlier with testosterone.Vaginae of one‐day and three‐week‐old BALB/c mice were transplanted into one‐day‐old and into three‐week‐old syngeneic hosts. Hosts were treated with various doses of estradiol. Irrespective of the age of the hosts, ovary‐independent hyperplasia or cornification occurred in transplants from one‐day‐old donors. Transplants from three‐week‐old donors showed only ovary‐dependent cornification. The results suggest, however, that both vaginal tissue age and host age play some role in determining the nature and occurrence of steroid‐induced persistent vaginal changes.
RNA synthesis in relation to DNA replication in synchronized Chinese hamster cell cultures
Authors: Klevecz Robert R. , Stubblefield Elton 
Published: June 2005

AbstractSelection and reversal of Colcemid‐blocked mitotic cells yielded synchronous populations of 90% purity, representing 10% of the original culture. This system gave sufficient material to allow the isolation of RNA, pulse‐labelled with tritiated uridine, in various stages of the cell cycle. Sucrose gradient sedimentation of such isolations showed that incorporation of the isotope into the most rapidly sedimentating RNA fractions was greater in S and G2 than it was in G1. In addition, the total amount of labelled RNA in a given pulse was greater following the initiation of DNA synthesis. The rate of RNA synthesis increased following mitosis and reached an initial plateau after one hour. A second increase in rate was observed three hours later, or about one hour after the beginning of DNA synthesis. Several peaks in synthetic rate seemed to be superimposed on the overall increase. Short pulse times appeared to accentuate the discontinuous nature of the rate curve, while longer pulse times made the cyclic peaks more obvious. Inhibition of DNA synthesis with 1 mM thymidine prevented the change in RNA synthetic rate from occurring.The doubling in RNA synthetic rate is interpreted to be the result of replication of the functional DNA templates. The periodic fluctuations in rate suggest that, although the potential for RNA synthesis is doubled with DNA replication, the rate at any instant is not totally determined by the gene dosage.
Activity of aminopeptidases (amino naphthylamidases) during early limb bud differentiation in the chick embryo
Authors: Karle N. Mottet 
Published: June 2005

AbstractThe morphologic changes in the differentiation of chick embryo limb buds from Hamburger‐Hamilton stages 19 through 34 were correlated with biochemical measurements of hydroxyproline biosynthesis and aminopeptidase enzyme activity. The distribution and quantitative approximations of collagen, mucopolysaccharides and aminopeptidase activity were observed by histochemical methods. Aminopeptidase enzyme activity increased after four days of incubation (stages 24‐25) concomitantly with the formation of precartilage masses (development of lakes of intercellular mucopolysaccharides). Histochemical preparations revealed the mesodermal cells in the precartilage masses to have an increased aminopeptidase enzyme activity. It was also noted that the enzyme activity in the ectodermal ridge was in excess of that found in the subjacent mesodermal cells or adjacent epithelium. Wet weights of limb buds revealed a constant rapid rate of growth throughout the period of study. However, aminopeptidase enzyme activity was not biochemically detectable until the onset of increased mucopolysaccharide synthesis, when cartilaginous differentiation begins. At five days (stage 26), hydroxyproline was first detectable biochemically and collagen histochemically. This was concomitant with the onset of hydroxyproline production in the embryo in toto, reported previously. The curve of acceleration of hydroxyproline production per milligram of bud mesoderm was less than the acceleration of aminopeptidase activity. The aminopeptidase enzyme activity in the premuscle masses and ectodermal‐mesodermal interface, where histochemically detectable collagen was located, was at the same level as the intervening tissues. After stage 19, limb bud mesoderm was cultured in vitro for seven days. Hydroxyproline production was not biochemically detectable and collagen not stainable, though mucopolysaccharide production was extensive. No muscle differentiation occurred and cell proliferation was minimal. Aminopeptidase enzyme activity had increased 20‐fold. It is suggested that at least part of the aminopeptidase enzyme activity of limb buds is associated with mucopolysaccharide synthesis. There was no evidence that it was associated with mesodermal cell proliferation, muscle differentiation, or hydroxyproline production.
Glucose metabolism and chick neurogenesis. II. 6‐phosphofructokinase and aldolase activity in the embryonic brachial spinal cord
Authors: Burt Alvin M. 
Published: June 2005

AbstractMicroquantitative procedures were employed for the assay of 6‐phosphofructokinase (6‐PFK) and aldolase activity in the brachial spinal cord of chick embryos from four and one‐half to 21 days' incubation. Activity of 6‐phosphofructokinase increased 9.2‐fold from stage 25 to stage 46. The ontogenetic pattern was characterized by two periods of rapid increase in enzymatic activity, from stage 25 (4 1/2 days) to stage 29 (6 days) and from stage 36 (10 days) to stage 42 (16 days). Aldolase activity increased 1.7‐fold from stage 25 to stage 46. The ontogenetic pattern showed a 50% increase in enzymatic activity during the 48‐hour period from stage 36 to stage 38. Several transient changes in level of activity for both 6‐phosphofructokinase and aldolase are described. The temporal patterns of both enzymes are discussed in relation to glucose‐6‐phosphate dehydrogenase activity, glucose metabolism and functional differentiation. The results of the present study suggest that glycolysis is relatively low during the early phases of neurogenesis, increasing just prior to a rapid decline in pentose cycle activity, and that glycolytic metabolism then increaases during the period of functional maturation.
The cell cycle during lens regeneration
Authors: Zalik Sara Eisenberg , Yamada Tuneo 
Published: June 2005

AbstractThe cell cycle in the proliferating zone of the lens regenerate of the adult newt, Triturus viridescens, was investigated by autoradiography using H3‐thymidine as the labeled precursor. For estimation of the DNA synthetic period (S period), we followed the changes in frequency of labeled mitoses after injection of the labeled precursor in 15‐day regenerates. The synthetic index of regenerates (number of labeled cells/number of cells in proliferation zone) was measured at 5, 8, 11, 15, 20, 25, and 30 days after lens removal.For 15‐day regenerates, the DNA synthetic period was estimated to be ca. 19 hours, the G‐2 period ca. 2 hours, the G‐1 period ca. 40 hours, and the cell generation time ca. 65 hours. The synthetic index increased with the progress of regeneration. Using the DNA synthetic period found for 15‐day regenerates, we calculated the average generation time for each stage of regeneration. It decreases from 11 days at stage I to 2.5 days at stages X and XI.
The course of mauthner axons in Janus‐headed Xenopus embryos
Authors: Swisher John E. , Hibbard Emerson 
Published: June 2005

AbstractSeveral studies have demonstrated that rotated segments of the embryonic hindbrain will repolarize to conform with the host gradients, and that the developing Mauthner (M‐) axons reorient accordingly, tending to follow a normal course. To investigate the response of these axons to an irreversibly antagonistic polarity, we prepared Janus‐headed telobionts in which initially descending M‐fibers would begin to ascend upon entering the opposite head. About one‐third of the fibers became disoriented within the graft region, evidently as a result of inadequate healing. The remaining two‐thirds traversed the graft and continued to ascend the opposite head past the medulla and into the midbrain and forebrain. The apparent ease with which these M‐axons made their way upgradient may have been enhanced by (1) inability of growth cones to respond to head‐on gradients; (2) selective fasciculation; (3) weakening of the rostrocaudal (longitudinal) gradients as a result of birostral telobiosis; and (4) growth through intact tissue.Most of these M‐axons negotiated a rostrocaudal polar inversion in much the same way as commissural fibers normally do in passing from lateral to medial, then from medial to lateral. We suggest that crossing fibers may be impeded by their encounter with the contralateral antagonistic gradient, and that for this reason the rostrocaudal directional tendencies of decussating axons are expressed only after the midline has been crossed. This hypothesis does not require assumptions of right‐left specificity or intricately coordinated timing of developmental events to explain decussation.
Nature of induced persistent vaginal cornification in mice. III. effects of estradiol and testosterone on vaginal epithelium in vitro
Authors: Kimura T. , Basu S. L. , Nandi S. 
Published: June 2005

AbstractVaginae of newborn BALB/c mice were cultured in vitro with or without 1 μg/ml of estradiol for 1‐3 days, and then transplanted into 4‐day‐old syngeneic hosts. Intermittent or persistent estrus was indicated by smears from many of these transplanted vaginae which had previously been cultured with estradiol, even after ovariectomy of the hosts. Those transplants which had been cultured for 2‐3 days with estradiol had thickened epithelium (hyperplasia), and cornification was observed histologically in some. In contrast, where estradiol was not used in the cultures, transplanted vaginae (controls) showed no cornification after host ovariectomy. Histologically, the epithelium of these controls was thin and in most cases slightly mucified. Vaginae of 3‐week‐old BALB/c mice, cultured with or without estradiol, resembled the controls, derived from newborn donors.When vaginae from newborn donors were cultured with 0.01‐ 5 μg/ml of estradiol for three days, and then transplanted into 4‐day‐old syngeneic hosts, ovary‐independent hyperplasia and cornification were observed in a number of the transplants. When vaginae from newborn donors were cultured in 0.001 μg/ml of estradiol, or in 0.001‐5 μg/ml of testosterone, neither persistent cornification nor hyperplasia was observed subsequent to transplantation. These results suggest that the mechanism of induction of persistent vaginal estrus in vivo by estradiol and by testosterone may be different. Whereas estradiol may act directly on the vaginal epithelium of newborn mice, the effect of testosterone would appear to be indirectly mediated.
Differentiation of black‐red melanin in the fowl: Interaction of pattern genes and feather follicle milieu
Authors: Brumbaugh J. A. 
Published: June 2005

AbstractThe multiple‐allelic E pattern series in the fowl is the major controller of black‐red melanin distribution. Embryonic grafting experiments showed that the melanoblasts of each pattern are autonomous. However, fasting and thyroxine‐feeding experiments with the normal (e+) adult changed the melanin distribution and showed that other factors also influence differentiation. It is suggested that the interaction between these genetic and environmental factors takes place in the zone of differentiation of the growing feather. The action of this zone upon the normal melanoblst is probably a function of time, and related to feather growth. Rapid movement of melanoblasts through this zone favors eumelanin synthesis, hence black bars appeared on red feathers when stimulated by thyroxine. Slow movement through this zone favors phaeomelanin synthesis, hence, with fasting, red bars appeared. In contrast to normal melanoblasts, the melanoblasts of the other E alleles differ in sensitivity to the action of the milieu in the feather follicle. The insensitive E/E melanoblasts become exclusively eumelanin‐producing melanocytes, while the hypersensitive ey/ey melanoblasts become mostly phaeomelanin‐producing melanocytes. The remaining alleles fall in between these two types in their response.
Effects of hormones on the renal response to unilateral nephrectomy in hypophysectomized rats
Authors: McCreight Charles E. , Reiter Russel J. 
Published: June 2005

AbstractThe roles of selected hormones in restoring the capacity of the remaining kidney following uninephrectomy of hypophysectomized rats to respond by tubular hyperplasia were explored. Autoradiography, using tritiated thymidine, was employed for identifying cells synthesizing new deoxyribonucleic acid within a standard period, a valid measure of mitotic activity. For animals with intact pituitary glands, both cortex and medulla of kidneys remaining three days after uninephrectomy exhibited a 3½‐fold increase in numbers of labeled cells over control levels. The amount of mitotic activity in either region of bilaterally intact kidneys of hypophysectomized animals was not significantly different from that for animals with intact pituitaries, but the compensatory renal hyperplastic response to uninephrectomy was reduced to one‐third. Either a small amount of growth hormone or a much larger amount of anterior pituitary extract, administered subcutaneously twice daily for several days, restored the compensatory response to uninephrectomy to levels obtained in rats with intact hypophyses. Adrenocorticotropic hormone depressed mitosis markedly in control kidneys of hypophysectomized animals and to an even lower level in remaining kidneys. Growth hormone would appear to be a necessary and effective component of the pituitary secretion in permitting compensatory renal hyperplasia to take place. Since prior studies have shown adrenalectomy to promote cellular division in renal tubules, it was assumed that the presently reported depression of renal mitosis by excess adrenocorticotropic hormone was mediated by an overactivity of the adrenal glands.
Studies of frog oviducal jelly secretion. II. Cytology of secretory cycle
Authors: Lee Peter A. 
Published: June 2005

AbstractElectron microscopy reveals that the secretory glandular cells of the oviduct of Rana pipiens contain granules which may develop from small vesicles with smooth membranes. The latter may represent dispersed Golgi elements, although cytochemical reactions fail to reveal a localized Golgi complex within these cells. Individual granules enlarge throughout the growing season without fusing with other granules. The mature cell is packed with granules, each of which possesses uniquely an interior electron‐dense (dense) part and an electron‐lucid shell enclosed by a smooth membrane. The dense part first appears as a condensed body. As growth proceeds, the dense component branches to form a net‐like pattern within the granule. When the granule has attained its mature size, the dense component appears to revert to a condensed pattern again. Cytoplasmic granules which are observable by light microscopy after staining with toluidine blue at pH 4.0 apparently correspond to the dense component seen in the electron microscope.