bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on differentiation of Müllerian ducts in the quail, Coturnix coturnix japonica. I. Collagen synthesis during duct differentiation
Authors: Yamamoto Masamichi , Koshihara Hidetoshi , Noumura Tetsuo 
Published: June 2005

AbstractPresent investigations were carried out in an effort to determine the mechanisms in avian Müllerian duct differentiation, especially those responsible for the asymmetrical differentiation in female embryos. Ultra‐structural study of events during quail development demonstrated the following: At an early embryonic stage, a central simple‐layered epithelial canal was thickly enclosed with loose connective tissue whose fibroblasts resided in interlacing feeble networks. These fibroblasts appeared to migrate easily while maintaining tenuous contacts by slender cytoplasmic processes. At later stages, the loose connective tissue became denser and more concentrated near the canal. Fixed fibroblasts were surrounded by bundles of self‐elaborated collagen fibers completing a tight commissure with the basement membrane of the epithelium in the left duct, but a tight commissure was not completed in the rudimentary right duct.Corresponding to ultramicroscopical features, collagen synthesis was estimated by 3H‐proline incorporation to be comparable to the 14C‐amino acids incorporated during duct differentiation. Specific activities revealed an apparent asymmetrical differentiation between the left and right ducts at an early embryonic stage when differences between both the ducts could hardly be discerned by electron microscopy. These incorporations in vitro were affected by the presence of estradiol at physiological concentrations and, indeed, exhibited certain differences between the left and right ducts in response to the presence of estradiol.
Testicular metamorphosis and prolongation of spermatogenesis in starlings (Sturnus vulgaris) in the absence of daily photostimulation
Authors: Rutledge James T. , Schwab Robert G. 
Published: June 2005

AbstractMale European starlings (Sturnus vulgaris) were held in constant darkness for 448 days. Testicular widths, measured in situ via unilateral laparotomy at two to four week intervals, revealed that testicular growth reached a size associated with spermatogenesis in an average of 101 days. The spermatogenic period persisted for an average of 296 days. Histological examination of testes from two birds after 280 days of treatment revealed mature sperm in the seminiferous tubules. Complete testicular involution did not occur. Current photoperiodic theory must be modified to explain testicular metamorphosis without daily photostimulation in an avian species known to be photoperiodic.
The fine structure of regenerating notochord in anuran tadpoles
Authors: Overton Jane , Mapp Frederick E. 
Published: June 2005

AbstractBecause normal growth as well as successful regeneration of the anuran tadpole tail depend upon outgrowth of the notochord, this process has been studied at the fine structure level to determine the mode of elongation of the regenerating notochord. The present work shows that in Rana pipiens cells at the apical region of the notochord send out numerous filopodia containing microtubules and microfibrils which may align with or attach to fibrillar bundles in the matrix of the fin. These apical cells adhere to each other at “primitive attachment sites” whereas the notochord cells at more anterior levels adhere more closely and show other specialized attachments; desmosomes, intermediate junctions and junctions of the gap or nexus type. A basement membrane is present near the tip, but is not continuous over the apical region. These findings suggest cell motility at the apex and possibly guidance by the fibrillar elements of the matrix. Therefore, the collagen fibers of the fin were examined by light microscopy after a number of fixation and staining procedures. No clearcut evidence of a regular antero‐posterior orientation of fibrils in the matrix of the fin which could guide outgrowth was found. Results are considered in connection with experiments on notochord regeneration.
Localization of dopa decarboxylase in adult Aedes aegypti females
Authors: Schlaeger Dorothy A. , Fuchs Morton S. 
Published: June 2005

AbstractAdult Aedes aegypti females contain very low levels of dopa decarboxylase activity. However, after a blood meal the activity of this enzyme rises dramatically.
Most of the dopa decarboxylase activity is lost after females are allowed to oviposit.
The bulk of the dopa decarboxylase activity observable was accounted for by direct assay of mature ovaries.
Blood feeding did not stimulate any increase of dopa decarboxylase levels in ovariectomized females.
It was concluded that after a blood meal the enzyme eventually becomes incorporated into the mature oocyte to be used for subsequent sclerotization when it is oviposited. Furthermore the presence of an intact resting ovary is necessary in order for the observed blood feeding stimulation of enzymatic activity to occur. This suggests that the follicular epithelium of the ovary may be the site of synthesis or activation of dopa decarboxylase.
Comparative study of the early embryonic cytology and nucleic acid synthesis of Ambystoma mexicanum normal and o mutant embryos
Authors: Carroll Carole R. 
Published: June 2005

AbstractMaternal effect mutations are useful tools which may aid in determining how the morphogenetic organization of the egg cytoplasm controls the plan of early development. One of the most interesting of the several maternal effect genes in the axolotl, Ambystoma mexicanum, is the o gene. It is unique in that all embryos of o/o females are affected in identical fashion, uniformly stopping development during gastrulation just when the main events of organ formation should be initiated. This paper is an investigation of the cytology, karyotype, and nucleic acid synthesis in mutant and control embryos and provides some important clues as to the mechanism of action of the o+ gene. Cell division and DNA synthesis in mutant embryos are sharply reduced at the mid‐late blastula stage. At this time in normal embryos, RNA synthesis is activated but is not in embryos of o/o females. The evidence from classical hybridization experiments and experiments with enucleated embryos suggests that this RNA synthesis is necessary for gastrular morphogenesis to take place. Thus the product of the o+ gene, the o+ substance, may be a stored regulator involved in genome activation during the late blastula stage which is required for the succeeding events of gastrulation. How it is involved in regulation remains to be worked out.
Ultrastructure of early development of mouse parthenogenones
Authors: Solter Davor , Biczysko Wieslawa , Graham Chris , Pienkowski Marek , Koprowski Hilary 
Published: June 2005

AbstractMouse eggs were parthenogenetically stimulated with hyaluronidase and osmotic shock and the resulting two‐, four‐ and eight‐cell stage embryos examined with the electron microscope. The ultrastructure of parthenogenones during cleavage showed numerous differences when compared with normal development. Cortical reaction was absent and there were no microvilli on the cell surface of developing blastomeres. The cytoplasm contained numerous bundles of fibrous material, vacuoles and lipid droplets, multivesicular bodies, and agglomerates of vesicles sometimes connected with cortical granules. Cortical granules and vacuolated mitochondria were numerous and usually situated near the cell membrane. The number of free ribosomes was very small and agglomerates of ribosomes or rough endoplasmic reticulum were not observed. Nucleoli in almost all cells were so‐called primary nucleoli consisting of a dense, osmiophilic core and narrow ring of granular material. In only a few cells was reticulation of nucleoli and formation of fibrillar and granular parts noticed. Nuclear fragments and nuclei with broken membranes were present in some cells. Primary nucleoli persisted during mitosis and were in close contact with chromosomes. Cytokinesis was irregular and small and large fragments of cytoplasm surrounded by membrane were often observed between dividing cells. Our results suggested that failure of parthenogenones to develop normally is probably caused by numerous disturbances during early cleavage. Incomplete cortical reaction, persistence of primary nucleoli, a probable disturbance in RNA and protein synthesis, and irregularities during nuclear and cellular division were observed in all embryos.
Variation in dry mass and volume of nonfertilized oocytes and blastomeres of 1‐, 2‐ and 4‐celled mouse embryos
Authors: Abramczuk J. , Sawicki W. 
Published: June 2005

AbstractNonfertilized oocytes and 1‐, 2‐ and 4‐celled embryos were obtained from superovulated mice. The dry mass of cells was measured with an interference microscope either through the zona pellucida or after its removal with pronase. Volume was calculated from measurement of the diameter of the cells. From the dry mass/volume ratio the concentration of dry substance was calculated. Fertilization caused a drastic reduction in dry mass and volume from 34.6 to 31.4 ng and 189,500 to 165,000 μm3, respectively, while the concentration of dry mass of ova increased from 18.3 to 19.0 g/100 cm3. One‐celled embryos obtained 17, 23 and 34 hours after HCG gradually reduced their dry mass from 31.4 to 27.5 ng whereas their volume remained unchanged at the level of about 165,000 μm3. The increase of concentration after fertilization is followed by its reduction to about 17.0 g/100 cm3 between 17 and 23 hours after HCG and later till 34 hours remains unchanged. Mean dry mass of the blastomeres of 2‐celled embryos is one half, whereas that of blastomeres of 4‐celled embryos is one fourth of the dry mass of 34 hours 1‐celled embryos. A pronounced diversity of both dry mass and volume of the blastomeres of the embryo after second cleavage was observed.
Blood‐group‐like substances in some marine invertebrates. III. Glycoproteins with blood‐group a specificity in the cephalopods Sepia officinalis L. and Loligo vulgaris Lam
Authors: Renwrantz Lothar , Uhlenbruck Gerhard 
Published: June 2005

AbstractTwo cephalopods, Sepia officinalis L. and Loligo vulgaris Lam., have been investigated for soluble inhibitors of anti human blood‐group agglutinins. Only a weak inhibition was observed with respect to human anti‐A isoagglutinin. In the agar‐gel double diffusion test, however, the test substances showed a very strong precipitation reaction with heterophile anti‐A from snails. The precipitation lines were identical with that of A substance from peptone. The A‐like substances found were identified as glycoproteins containing terminal, non‐reducing bound α‐N‐acetyl‐D‐galactosamine. The biological importance of these macromolecules is discussed with particular reference to their reactive site.
A perfusion study of the effect of stanniectomy on the net influx of calcium 45 across an isolated eel gill
Authors: Fenwick James C. , So Ying Peng 
Published: June 2005

AbstractThe effect of stanniectomy on the net influx of calcium 45 across the gill membrane was investigated using an isolated individual gill perfusion preparation. Two weeks post‐operatively the gills from stanniectomized eels displayed a considerably higher net calcium uptake relative to the gills from mock‐operated eels. This finding supports the suggestion that the characteristic hypercalcemic response to stanniectomy is due, at least in part, to an increase in branchial calcium uptake.
Pair formation in Tetrahymena pyriformis, an inducible developmental system
Authors: Bruns Peter J. , Brussard Trudy B. 
Published: June 2005

AbstractThe process of pair formation by sexual strains of Tetrahymena pyriformis is an inducible pathway interrupting the cellular activities of vegetative growth. A specific series of events leading from vegetatively growing cells to mating pairs is described. The sequence is composed of two separate stages: initiation and co‐stimulation. Initiation is the response to certain starvation conditions, is sensitive to tonicity, is independent of mating types, and takes about two hours at 30°C. Co‐stimulation is a reaction between already initiated cells of different mating types, requires specific cell‐cell interactions, takes about one hour at 30°C, and results in stimulated cells which are able to form pairs. An understanding of the sequence leading to the programmed developmental activities of conjugation makes possible efficient mating techniques and facilitates a search for genetic and physiological constituents of the entire pathway.
Some characteristics of the zona pellucida antigen in the hamster
Authors: Garavagno Anita , Posada Joaquin , Barros Claudio , Shivers C. Alex 
Published: June 2005

AbstractAntibody prepared in rabbits against saline extracts of hamster ovary forms a precipitate on the zona pellucida surface of oviducal eggs and immature oocytes of adult and prepubertal females. The precipitate appears in a net‐like arrangement on the outer surface only and reflects the heterogeneity of the zona. The antibody diffuses through the cumulus cells of oviducal eggs but not the cumulus cells of ovarian oocytes. Trypsin digests the inner nonprecipitated portion of the antibody treated zona but not the outer precipitated region.An important role for the zona antigen in sperm to zona attachment and in zona penetration is indicated by: (a) the failure of sperm to attach to the zona pellucida surface following treatment of eggs with antibody; (b) the polarity of the distribution of antigen in the zona; (c) the species‐specificity of the antigen; (d) the attachment of sperm to only the outer surface of zona ghosts; (e) and the concentration of the antigen at the surface of the sperm slits in the zona.
Secretion of collagen by corneal epithelium. II. Effect of the underlying substratum on secretion and polymerization of epithelial products
Authors: Dodson James W. , Hay Elizabeth D. 
Published: June 2005

AbstractCorneal epithelium isolated with EDTA from 5–11 day old chick embryos was grown on a variety of substrata in organ culture to judge the effect of the substratum on the ability of the epithelium to produce a corneal stroma. When grown on the capsule of either living or frozen‐killed lens, the corneal epithelium synthesized and secreted a proline‐rich product (as judged by autoradiography) which was shown by electron microscopy to accumulate under and within the epithelium in the form of striated collagen fibrils, many of which were 250 Å in diameter and arranged at right angles to one another as in the normal corneal stroma. Basal lamina formed, but was not continuous under the epithelium. On EDTA‐treated frozen‐killed corneal stroma, new basal lamina formation was difficult to detect because of the persistence of the old basal lamina on the stroma. When this old basal lamina was digested by trypsin, the remaining corneal stroma failed to promote new basal lamina formation by the epithelium unless the stroma contained living fibroblasts. When grown on rat tendon collagen gels, epithelia produced a proline‐rich product which seemed to polymerize in the gel instead of forming a cornea‐like stroma. Millipore filter failed to elicit any basal lamina or collagen fibril formation. The data presented in this paper are consistent with the hypothesis that juxtaepithelial extracellular matrix may provide cell surface‐stabilizing factors which promote corneal epithelial differentiation.
The neurotrophic influence on RNA precursor incorporation into polyribosomes of regenerating adult newt forelimbs
Authors: Bantle John A. , Tassava Roy A. 
Published: June 2005

AbstractThis study was designed to determine the effect of denervation on RNA and protein precursor incorporation into polyribosomes of nerve‐independent regenerates of the adult newt, Notophthalmus viridescens. The three stages of regeneration chosen for experimentation were the late paddle‐early digit stage (day 21), the 2–3 digit stage (day 28) and the 3–4 digit stage (day 35). Right forelimbs were denervated two days prior to polyribosome extraction while left forelimbs served as controls. To measure precursor incorporation, each newt was given either (1) H3‐uridine (six hours), (2) Na3P32O4 (90 minutes), or (3) H3‐amino acids (60 minutes). Following incorporation, regenerates were prepared for examination of either polysome profiles or polysomal RNA profiles. A technique was used which yielded undegraded, non‐membrane bound polyribosomes relatively uncontaminated by labeled cosedimenting material. It was found that denervation reduced the incorporation of RNA precursors into both ribosomal and putative messenger RNA of polyribosomes of all three stages examined. Of the three stages tested, the 35 day stage was least affected by denervation. Amino acid incorporation into polysomal nascent peptides of regenerates was also adversely affected.
Deafferentation studies on motor activity in the chick. II. Activity pattern of wings
Authors: Narayanan C. H. , Malloy R. B. 
Published: June 2005

AbstractA study of the effects of deafferentation of the brachial level of the spinal cord in chick embryos was undertaken to examine the influence of afferent input on activity patterns of the wings, during embryonic, hatching and posthatching periods. Neural crest precursors of dorsal root ganglia were destroyed by superficial cauterization at somite levels 17 to 21 in embryos of stages 13–14. Between nine and 17 days of incubation no significant differences were observed in the frequency of wing movements as part of either total or local activity patterns. The prehatching and hatching behavior patterns were typical except that none of the experimental embryos managed to tuck the head under the right wing (tucking phase). Wing lifting and lowering were absent between day 18 and hatching. In hatched chicks, wings were incable of making synchronous bilateral flapping movements. The results indicate that afferent input from the wings to the spinal cord is probably involved in the patterning of wing movements. In the absence of afferent input, the chick embryos show gross disturbances in the pattern of behavior involving the wings during hatching and after hatching.
Nuclear transplantation from specialized and unspecialized gut epithelial cells of adult Xenopus laevis
Authors: McAvoy J. W. , Dixon K. E. 
Published: June 2005

AbstractTwo types of epithelial cells from the small intestine of adult Xenopus laevis were used as donor cells for nuclear transplantation. One type was morphologically and functionally unspecialized and mitotically active, whereas the other type was specialized and mitotically inactive. The similarity in the over all patterns of development of the two sets of transplants showed that these differences in the state of the donor cells did not affect the ability of their nuclei to support development after transplantation.
Correction of developmental abnormalities resulting from localized ultra‐violet irradiation of an amphibian egg
Authors: Malacinski George M. , Allis Charles D. , Chung Hae‐Moon 
Published: June 2005

AbstractUltra‐violet irradiation of the vegetal hemisphere of uncleaved R. pipiens eggs results in the development of characteristic defects in neural morphogenesis. These defects can be prevented from occurring if U.V. irradiated embryos are either (1) incubated at low temperature (cryoreversion), (2) microinjected with oocyte homogenate, or (3) surgically manipulated by replacing their dorsal lip with the lip of a normal (non U.V. irradiated ) embryo at the time of gastrulation.
The effects of temperature and photoperiod on antifreeze production in cold water fishes
Authors: Duman John G. , De Vries Arthur L. 
Published: June 2005

AbstractA macromolecular “antifreeze” is present in the blood serum of fishes that inhabit subzero waters in winter. During the summer the “antifreeze” is not present. The effect of temperature and photoperiod on this circ‐annual cycle of “antifreeze” production was investigated. Fishes collected from subzero waters were acclimated to various temperature and photoperiod regimes. Only the combination of a long photoperiod and warm temperature resulted in the disappearance of “antifreeze” from the serum, thus providing for an efficient failsafe system. The time necessary for the complete loss of the macromolecular “antifreeze” ranged from 3 to 5 weeks. When summer fish were acclimated to various combinations of temperature and photoperiod, low temperatures resulted in the production of “antifreeze” regardless of the photo‐period. Serum Na and Cl−levels were significantly higher in cold acclimated than in warm acclimated fish. In general, fishes collected from more northerly latitudes had lower serum freezing points than the same species from warmer, more southerly waters. There seemed to be a genetic difference between populations ofAnoplarchus purpurescensfrom Amchitka, Alaska and San Simeon, California since the California fish were unable to produce “antifreeze” when acclimated to cold temperatures.
Dramatic mitotic response in planarians after feeding, and a hypothesis for the control mechanism
Authors: Baguñà Jaume 
Published: June 2005

AbstractUsing a new technique to stain and count planarian mitotic cells, a very rapid increase in neoblast mitotic activity has been found following feeding. The increase becomes visible 1 hour after feeding, reaches a maximum in 3–8 hours, and lasts for almost a week. These results suggest that a substantial proportion of neoblasts in the intact worm must be in the G2 phase ready to enter mitosis. The fact that the mitotic figures occur throughout the parenchyma also suggests that the stimulus may be of a neurohumoral kind.
The effect of hydrocortisone on the sheep red cell response in adult Xenopus laevis, the South African clawed toad
Authors: Ruben Laurens N. , Vaughan Margaret R. 
Published: June 2005

AbstractThe effect of hydrocortisone on the anti‐erythrocyte (SRBC) response of the South African clawed toad, Xenopus laevis, was studied. Hydrocortisone was administered two days prior to antigen injection and was found to reduce the eight‐day antigen‐binding response of sensitized spleen cells to 17% of its normal peak value. Control animals received injections of the vehicle solution the hormone is normally suspended in. Hemagglutination assays were also performed to ascertain whether the hydrocortisone treatment merely altered the ability of the spleen cells to bind antigen or suppressed their ability to produce antibody. Serum antibody titers were found to be depressed to 9% of the peak value by hydrocortisone treatment. Both thymus and spleen cells from the sensitized, hydrocortisone‐treated and control adult Xenopus were tested by immunocytoadherence. Unimmunized animals were also used to establish background levels. It was found that while the antigen‐binding response by immunized spleen cells was greatly decreased by hydrocortisone, thymocytes were particularly effected as their antigen‐binding capacities were reduced to background levels. It was concluded that these data support the view that the toad immune system is comparable to the mammalian with regard to hydrocortisone sensitivity of the anti‐red cell response.