bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of the T locus on fertilization in the house mouse
Authors: Olds P. J. 
Published: June 2005

AbstractMale mice carrying certain combinations of alleles at the T locus are known to be completely sterile, due to the inability of the spermatozoa to reach the site of fertilization. In this study, such spermatozoa were injected into the ovarian bursa of ovulating females, thereby allowing the spermatozoa to reach the eggs. However, the eggs were not fertilized, and perhaps not even penetrated. Spermatozoa from fertile males carrying only one t allele, or from males having no t alleles, when injected into the ovarian bursae of ovulating females, did produce pronuclear and two‐cell zygotes. Penetration of spermatozoa after bursal injection of T/t spermatozoa occurred later, and the eggs' pronuclear stage length was shorter, than after bursal injection of spermatozoa from males having no t alleles or after mating to T/t males, suggesting that the spermatozoan can influence the egg at the pronuclear stage, and that the physiological environment of the spermatozoa can influence the behavior of the spermatozoa during and after penetration of the egg.
The regulation of ovulation in the tsetse‐fly, Glossina pallidipes Austen
Authors: Odhiambo Thomas R. 
Published: June 2005

AbstractThe tsetse‐fly female matures a single oocyte at a time. It ovulates this into the uterus, where it hatches, develops into a fully‐grown larva, and is later larviposited by the mother. It is only then that the next mature oocyte is ovulated, and the whole sequence is repeated. Thus, in this insect, it is possible to differentiate clearly four processes of egg production: (1) oogenesis, (2) oocyte growth and vitellogenesis, (3) ovulation, and (4) oviposition (in this case, larviposition). Mating is necessary to initiate the process of ovulation, but it is not necessary for the earlier processes. In virgin females, oogenesis, oocyte growth and vitellogenesis takes place normally; but the sequentially matured oocytes are lysed within the egg chambers without being ovulated.
The role of protein synthesis in prefission morphogenesis of Paramecium aurelia
Authors: Suhama Mikio , Hanson Earl D. 
Published: June 2005

AbstractThe effect of cycloheximide on formation of contractile vesicles, development of buccal anlage, and fission in Paramecium aurelia was examined. Paramecium exhibits remarkably strong resistance to this inhibitor of protein synthesis. With continuous exposure to lower concentrations (0.14 to 0.94 mg/ml), the daily fission rate is reduced in proportion to the concentration of cycloheximide and is maintained at a constant level. Exposure to higher concentrations (1.83 mg/ml) starting at various specific times in the interfission cycle reveals transition and stabilization points for each morphogenetic event; exposure prior to the transition point completely blocks development of a given event, but after the stabilization point exposure does not affect morphogenesis, and between these points blockage may or may not take place. The formation of the contractile vesicles is a morphogenetic process distinct from other events related to cell division. It occurs earlier than oral morphogenesis and fission and occurs in a step‐wise fashion with the anterior vesicle appearing first and then the posterior one. For fission and buccal development the transition and stabilization points are very similar to those found previously for actinomycin D treatments, suggesting that translation follows immediately on transcription. Resorption of new vesicles was observed; buccal anlage were never resorbed.
Results of selection for susceptibility and resistance to trypan blue teratogenesis in a four‐way outcross mouse population
Authors: Beck Sidney L. 
Published: June 2005

AbstractA four‐way cross mouse population was established and four successive generations of animals were treated with trypan blue, selection being applied for susceptibility and resistance to the teratogen. The selection was successful, 26.8 ± 1.7% of all animals in the susceptible line (CBHA‐S) being abnormal and only 8.6 ± 1.7% of resistant (CBHA‐R) individuals being affected by the treatment. An unselected control line (CBHA‐C) produced an intermediate frequency of abnormality when treated. The vast majority of the abnormalities produced were of the tail and involved kinking, shortening, vertebral fusions and the occurrence of a completely novel malformation—an accessory tail. Both the proportion of litters affected by the treatment and the proportion of abnormal individuals within affected litters differed in the selected lines.
Calcitonin and ultimobranchial glands in fishes
Authors: Pang Peter K. T. 
Published: June 2005

AbstractUltimobranchial bodies in fishes contain follicles or cords of cells which show features of endocrine secretion. Hypocalcemic activities are present in the ultimobranchial bodies of sharks, bony fish and lungfish. Amino acid sequence of salmon calcitonin has been revealed and this hormone has been synthesized in vitro. Administration of mammalian and fish calcitonins has no effect on serum calcium levels of sharks, channel catfish, killifish and coho salmon. Mammalian and fish calcitonins elicit hypocalcemia and hyperphosphatemia in fresh water eels but not in sea water eels. Glandular hyperactivity can be related to calcium metabolism only in some cases. An osmoregulatory function of the gland has been suggested. The activity of this gland seems to be under pituitary control.
The ultimobranchial body of reptiles
Authors: Clark Nancy B. 
Published: June 2005

AbstractReptilian ultimobranchial bodies, located anterior to the heart in the region of the thyroid and parathyroid glands, are composed of cell cords and follicles. The cells show secretory activity and are similar histologically and ultrastructurally to ultimobranchial tissue from other vertebrate classes. Turtle ultimobranchial glands are unusual in containing numerous cytoplasmic granules or bodies which appear to be associated with the material seen within the ultimobranchial follicles.Ultimobranchial extracts from lizards or turtles can induce hypocalcemia in rats. However, calcitonin preparations or ultimobranchial extracts have not induced any significant change in blood calcium or phosphate values in reptiles. Further studies are required in order to clarify the role of the ultimobranchial bodies in this diverse vertebrate group.
The ultimobranchial gland of birds and the effects of nutritional variations
Authors: Bélanger Leonard F. 
Published: June 2005

AbstractHistological studies have revealed that the ultimobranchial gland of birds consists of duct‐like follicles which are of pharyngeal origin and parenchymal cords apparently derived from the neural crest. Aberrant parathyroid tissue, lymphoid cells and pseudo‐eosinophils are frequently found. The arterial supply of the ultimobranchial body is regulated by the presence of a sprial type of spincter. The parenchymal cells respond by hypertrophy and hyperplasia to hypercalcemia and by a decrease in secretory activity during prolonged hypocalcemia.At the electron microscopic level, these cells resemble the C cells of the mammalian thyroid. In the chick, they are presumed to be the only source of calcitonin. In other birds, such as the pigeon and the turtle‐dove, the ultimobranchial gland shares this function with the thyroid.The calcium‐lowering factor, calcitonin, acts on bone at least partly by inhibiting the bone resorptive activity of the osteocytes (osteocytic osteolysis) which is governed by the parathyroid hormone.
The constancy of cortical units in tetrahymena with varying numbers of ciliary rows
Authors: Nanney D. L. 
Published: June 2005

AbstractThe number of cortical units per ciliary row, estimated by counts of argentophilic elements in Chatton‐Lwoff preparations, declines as the number of ciliary rows rises. The total number of cortical units in the entire cell is not demonstrably correlated with the number of ciliary rows. These observations imply that the mechanisms governing the total supply of cortical units are independent of the mechanisms governing their spatial deployment.
Timed reciprocal dermal‐epidermal interactions between comb, mid‐dorsal, and tarsometatarsal skin components
Authors: Lawrence Irvin E. 
Published: June 2005

AbstractThe epithelio‐mesenchymal interactions in development of chicken comb were studied in 106 skin chimeras grown on the chorioallantois. Explants were formed by enzymatic separation and recombinations of epidermis and dermis from the comb area, the mid‐dorsum, and the tarsometatarsus, at stages before and during primordia formation. Under the experimental conditions, reciprocal developmental roles for comb dermis and epidermis were revealed. Comb dermis determines regional character and induces comb type epidermis. The strength of the inductive stimulus is too weak to erase feathers and scales induced (determined) in older mid‐dorsal and tarsometatarsal epidermis. Comb area epidermis of younger developmental stages can respond to feather and scale induction, but older comb epidermis may continue along its initial course of induction. Indeed, when comb epidermis of eight days and older is placed in contact with other dermis it appears to have an inductive role for comb. The onset of keratinization by 13 days limits comb tissue interaction. The respective roles for dermis and epidermis and critical periods in comb development are discussed.
Normal and induced synthesis of δ‐aminolevulinic acid synthetase in developing chick liver
Authors: Simons J. A. , Boell E. J. 
Published: June 2005

Abstractδ‐Aminolevulinic acid synthetase activity in embryonic chick liver is not detectable until just before hatching when it surges to more than four times the adult level (12 moles ALA/g liver/h) which is reached in the first week after hatching. An injection of 3, 5‐dicarbethoxy‐1, 4‐dihydrocollidine into the egg results in a massive increase in the activity of the enzyme—up to 40 times the adult level. In addition, the enzyme can also be induced in embryonic chick liver by hypoxia.
A method for the production of pigmentless eggs in Xenopus laevis
Authors: Dumont James N. , Eppig John J. 
Published: June 2005

AbstractPigmentless oocytes may be obtained from adult Xenopus laevis females by a combination of repeated induced ovulations with human chorionic gonadotrophin (HCG) and the continuous administration of the antimelanogenic compound phenylthiourea (PTU). Pigmentless eggs obtained in this manner are apparently normal since they may be fertilized and subsequently develop into normal, but pigmentless, embryos and tadpoles. Cessation of the PTU and HCG treatments results in normal pigmentation of immature oocytes; however, those oocytes which are more nearly mature become pigmented to a lesser degree. Those oocytes which are mature at the time treatment is stopped remain pigmentless.
On neurogenetic relations in Drosophila melanogaster
Authors: Chiarodo Andrew , Reing C. Michael , Saranchak Harry 
Published: June 2005

AbstractThe thoracico‐abdominal nerve centers of several winged but flightless Drosophila mutants were examined. Cell number estimates were made for the ganglia of bithorax, vestigial, cut, taxi, and Curly mutants, as well as of wild type flies. No numerical hypoplasia was observed in any of the mutants examined, thus confirming the original conclusion of Power ('50) that inability to fly is not correlated with a hypoplasia of the thoracico‐abdominal nerve center.A numerical hyperplasia was observed in the bithorax and vestigial mutants. The hyperplasia in the bithorax mutant is discussed in relation to the increased peripheral field in the thorax, caused by the action of the bithorax gene. The cause of the hyperplasia in the vestigial mutant remains unknown.
Expression of embryonic and adult erythrocyte antigens in hematopoietic repopulated x‐irradiated chickens
Authors: Sanders Bob G. , Wiley K. L. 
Published: June 2005

AbstractAn antigen is present on the red blood cells of embryonic and young chickens which is lost during development and is undetectable on the red blood cells of adult chickens. In this study, two experiments were performed to determine the presence or absence of the embryonic antigen. First, spleen, liver and bone marrow cells obtained from three day old chicks were transplanted into x‐irradiated adult chickens in order to determine if the embryonic antigen would be expressed on red blood cells in an adult environment but arising from transplanted “young” cells. Red blood cells from the adult x‐irradiated chickens were assayed at various intervals after transplantation for the presence of the embryonic antigen. Additional red blood cell antigenic markers other than the embryonic antigen demonstrated repopulation in the x‐irradiated chickens, but the embryonic antigen was not detectable. Second, three day old, non‐irradiated chickens were transplanted with adult chicken bone marrow cells and their red blood cells assayed at varying intervals up to 40 days in order to determine the effect of a “young” environment upon adult cells. These chickens continued to express the embryonic antigen on all their red blood cells; i.e., no adult‐like cells were found up to 40 days. The x‐irradiation‐transplantation studies indicate that the erythropoietic stem cells containing gene(s) coding for the embryonic antigen are repressed in the adult chicken and that in the young chicken repopulated with adult hemopoietic cells the gene(s) are derepressed.
Effects of injury and stimulation of the hypoglossal nerve and superior cervical ganglion on the mitotic activity of the glossal epithelium
Authors: Hall R. G. 
Published: June 2005

AbstractNerves affect the mitotic activity of the tissue that they innervate. The type of effects depend upon the nerve fiber types and conductive activity of the nerve. This was demonstrated by transection or stimulation of the hypoglossal nerve and removal or stimulation of the superior cervical ganglion. Transection of the right hypoglossal nerve produced an average increase of 18.5% in the mitotic activity of the right glossal epithelium. Stimulation of this nerve decreased the mitotic activity by 17.5%. Removal of the right superior cervical ganglion caused an average decrease of 18.4% while stimulation of this ganglion increased the mitotic activity by 17%.
Motility in chick embryos with substitution of lumbosacral by brachial by lumbosacral spinal cord segments
Authors: Narayanan C. H. , Hamburger Viktor 
Published: June 2005

AbstractIn two and one‐half‐day chick embryos, brachial segments were substituted for lumbosacral segments (Bl series) and vice versa (Lb series). Recordings were made of spontaneous (type I) motility in 9‐ to 17‐day embryos at daily intervals. Total embryonic motility (per cent time spent in activity in 10‐minute periods) and total wing and leg motility did not differ significantly from normal in both series. Furthermore, frequency of movements (per minute) was recorded for wings and legs separately and for combined wing/leg movements. In both experimental series, combined wing/leg movements were significantly more frequent and isolated wing or leg movements less frequent than in normal embryos. This means that two brachial or two lumbosacral segments in the experimental embryos are more tightly coupled than the brachial and lumbosacral segments in a normal embryo. Regional differences between brachial and lumbosacral segments are thus demostrable as early as nine days. The increased frequency of combined wing/leg movements persists after hatching. In hatched chicks of the Bl series, legs are incapable of making alternating stepping movements; they are always abducted and adducted simultaneously as in wing flapping. This is another expression of regional specificity of the brachial cord. We assume that regional specifications of spinal cord segments are built into the cord at the stage of operation.
In vitro maturation and ovulation of oocytes of the catfish, Heteropneustes fossilis (Bloch): Effects of mammalian hypophyseal hormones, catfish pituitary homogenate, steroid precursors and metabolites, and gonadal and adrenocortical steroids
Authors: Goswami Shashi V. , Sundararaj Bangalore I. 
Published: June 2005

AbstractWolf and Quimby medium and its modified chemically‐defined version were found to be most suitable among the eight media tested for shortterm culture of oocytes of the catfish, Heteropneustes fossilis. The modified Wolf and Quimby was employed to evaluate the relative effectiveness of several hypophyseal and steroid hormones, as well as steroid precursors and metabolites in inducing in vitro maturation and ovulation in the catfish oocytes. With the exception of ovine luteinizing hormone (LH) which gave only a marginal response even at high dose levels, other mammalian hypophvseal hormones (FSH, TSH, LtH, STH and ACTH) and catfish pituitary homogenate were incapable of inducing oocyte maturation. Of the steroid precursors tested, pregnenolone, progesterone and their 17 α‐hydroxy derivatives were slightly effective in inducing oocyte maturation at high concentrations. Steroid metabolites (pregnanediol‐20 β) were ineffective. The sex steroids (testosterone, estrone, estriol and estradiol) did not induce oocyte maturation, while dehydroepiandrosterone and androstenedione gave only a nominal response even at high doses. Corticosteroids, principally hydrocortisone (F) and desoxycorticosterone (DOC) as also their acetates, were the most potent maturation‐inducing agents even at low concentrations. These results strongly suggest that inasmuch as LH and catfish pituitary homogenate per se do not induce oocyte maturation in vitro, the terminal hormones which act directly on the oocytes to induce maturation and ovulation are the corticosteroids principally, DOC and F. The significance of these findings in the hormonal control of ovulation in the catfish is discussed.
Effects of experimental degradation of microtubules on the growth of cultured nerve fibers
Authors: Handel Mary Ann 
Published: June 2005

AbstractNerve fiber outgrowth and elongation were studied in spinal ganglia explants cultured with NGF. The effects of cold and colchicine treatments on the degradation of microtubules and on the outgrowth and elongation of nerve fibers were determined. Colchicine inhibited nerve fiber outgrowth and elongation, and degraded the microtubules of the nerve cells, producing an abundance of 100 Å filaments. Cold treatment inhibited fiber outgrowth and elongation, but did not induce degradation of the microtubules of the nerve fibers. The effect of cold treatment on the growth of nerve fibers was reversible. The microtubules of these nerve fibers therefore exhibited differential stability in reaction to microtubule degradative agents, in that they were degraded by colchicine and were resistant to cold treatment. The results indicate also that microtubules may be involved in the outgrowth and elongation of nerve fibers. However, since nerve fibers exposed to colchicine did not retract, it is suggested that microtubules may not be solely responsible for the maintenance of the fiber processes of these cells, but that contacts with other cells and with a supporting matrix could be important in the maintenance of the asymmetric nerve cell processes.
The occurrence of stage specific antigens during early sea urchin development
Authors: Westin Monica 
Published: June 2005

AbstractRabbit antisera to homogenates of unfertilized sea urchin eggs were absorbed with pluteus extract. In the same way, antisera to gastrulae or plutei were also made “stage specific” by absorption with extracts of eggs. When tested by means of immunoelectrophoresis the absorbed sera formed precipitates with antigens in extracts from homologous developmental stages. Precipitates of such stage specific antigens were removed from the agar plates and reinjected into rabbits. In this way, monospecific antisera to four stage specific antigens were obtained. Upon closer analysis, the egg specific antigen was found to be heterogeneous, consisting of two components. Both components decreased in concentration and had disappeared by the time of gastrulation. The two pluteus specific antigens seemed to be absent from eggs and earlier stages. By means of isotope incorporation experiments and autoradiography of immunodiffusion plates, it was found that one of these antigens became detectable at the mesenchyme blastula stage while the other was first detected at the prism stage. The fourth antigen, which was clearly detectable from gastrulation onwards, was found to be already present in the unfertilized eggs but at much lower concentrations than in late developmental stages.
The extent of cell contact and the relative frequency of small and large gaps between presumptive mesodermal cells in normal gastrulae of Rana pipiens and the arrested gastrulae of the Rana pipiens ♀ × Rana catesbeiana ♂ hybrid
Authors: Johnson Kurt E. 
Published: June 2005

AbstractA comparison was made of the area of cell contact and the relative frequency of small and large intercellular gaps in contacts between presumptive mesodermal cells in 21 hour normal Rana pipiens early gastrulae and hybrid R. pipiens ♀ × R. catesbeiana ♂ arrested gastrulae. Normal cells contact neighbors over a large percentage of the cell surface and are usually polygonal. Hybrid cells contact neighbors over a small percentage of the surface and are usually rounded. An objective method was utilized for choosing contacts and for measuring gap dimensions at regular intervals along the contacts. These measurements show that small gaps are more frequent and extensive in normal presumptive mesodermal cells. These results are discussed in terms of the fine structural bases for differences in cell contact behavior.
Postnatal changes in microtubular protein content in several regions of the mouse brain
Authors: Twomey Stanley L. , Wyttenbach Charles R. 
Published: June 2005

AbstractQuantitative postnatal changes in colchicine‐binding protein are reported in four regions (cerebrum, thalamus‐hypothalamus, brain stem and cerebellum) of the mouse brain. Relative to unit protein and unit wet weight, changes of −27% (cerebrum) to −53% (cerebellum) occur from day 1 to young adult, with the declines taking place prior to day 7 only in the cerebellum. On the basis of total activity per brain region, however, all areas show a several‐fold increase in colchicine‐binding protein. Thus a true loss of this protein does not occur; rather, its synthesis just fails to keep pace with that of non‐tubulin protein and with the increase in tissue mass.Assay of the brain from 21 day “reeler” mutants reveals no deviations from normal controls even in the extensively retarded cerebellum.The several factors which quantitatively affect microtubular protein are discussed. It is concluded that the maturational decline per unit protein is most likely due to the growth and myelination of axons, while the increase in total tubulin is due mainly to extensive dendrite formation. More specific relationships cannot presently be made owing to the lack of more quantitative histological information as to changing cell structure in each region and to the cellular heterogeneity of the regions analyzed. From this study it is clear, however, that real spatial and temporal differences in microtubular protein content exist within the brain.
Organ and species specificity of mouse uterine alkaline phosphatase
Authors: Dufour D. , Tremblay A. , Taskar S. , Estrada R. 
Published: June 2005

AbstractAn alkaline phosphatase was isolated from saline extract of mouse uterus by the method of isoelectric focussing. The organ and species specificity of this protein was demonstrated by immunodiffusion studies. This phosphatase was localized immunohistochemically in the endometrical epithelium of mouse uterus.