bluuebunny/crossref_metadata_2025_split huggingface dataset:
Biometrical problems in the study of early mammalian embryos in vitro
Authors: Biggers J. D. , Brinster R. L. 
Published: June 2005

AbstractDuring recent years techniques have been evolved which permit the development of embryonic mouse cleavage stages in vitro. These methods are now sufficiently reliable for use in quantitative experiments such as the mapping of concentration‐response surfaces to discover the interaction of effects produced by various components of the medium. In studies on the development of mouse embryos in vitro conducted in our laboratory, a series of specialized biometrical problems has arisen.In the present paper, the theoretical basis for analyzing the responses of two‐cell mouse ova in vitro is discussed. The responses are quantal in nature and are transformed before statistical treatment. The application of the angular and probit transformation to this data is illustrated. In certain cases, allowances must be made for a control portion of embryos failing to develop. The analyses are illustrated by two examples, one concerned with the determination of optimum conditions, and the other with the estimation of the median effective dose of a metabolic inhibitor.
Fat body cycling and experimental evidence for its adaptive significance to ovarian follicle development in the lizard Uta stansburiana
Authors: Hahn William E. , Tinkle Donald W. 
Published: June 2005

AbstractThe annual fat body cycle in the lizard Uta stansburiana is associated with reproduction. In females fat bodies decline in late winter and early spring when deutoplasm is deposited in the ovarian follicles. Males have a similar fat cycle, but fat bodies are much smaller. Ovariectomy eliminated rapid lipid mobilization from the fat bodies which occurs in sham operated controls. Fat body removal from early estrus females induces high incidence of follicular atresia and retards the rate of yolk deposition. Follicular growth is delayed or inhibited if fat bodies are excised from preestrus animals. The amount of extractable lipid in the pre‐estrus fat body is nearly equivalent to the lipid in a typical egg clutch. The adaptive value of the fat bodies is apparently associated with the formation of the first egg clutch which in accordance with population studies is the most important clutch.
The stimulus for case‐building activity in caddis‐worms (Trichoptera)
Authors: Merrill Dorothy 
Published: June 2005

AbstractIn four species of caddis‐worms,‐Ptilostomis semifasciata (Say), Platycentropus radiatus (Say), Limnephilus indivisus Walker, and Pycnopsyche guttifer (Walker), —removal of the anal hooks and the posterior hair sensilla significantly prolonged case‐building activity with a resulting increase in case production. The extensive building was of the rough provisional type, which is normally completed within a few hours. There were differences among the species with regard to the amount of excessive building and the relative importance of the hairs.Transection of the ventral nerve cord appeared to block the extensive building that normally followed hook removal.It is proposed that the stimulus for building is an endogenous process which causes excitatory impulses to be emitted from the several ganglia. The impulses go forward to the integrative areas controlling the animal's building apparatus and stimulate building. The emission of impulses from the ganglia is inhibited by sensory input from contact with the case.
Hypertrophy of the islets of Langerhans of frog tadpoles after partial pancreatectomy
Authors: Frye B. E. 
Published: June 2005

AbstractSubsequent to incomplete surgical removal of the dorsal pancreatic rudiment of Rana pipiens embryos, islets of Langerhans arise in the pancreas, but in smaller amount than normal. Conpensatory hypertrophy of the beta cells occurs, and the islets are transformed from a larval into an adult histological type. Larval growth and metamorphosis is otherwise unaffected. The evidence supports the hypothesis that metamorphic maturation of the islets of Langerhans is a consequence of an increase in the functional demand on the islets of the frog as compared to the tadpole, and not to direct metamorphic effects of thyroxine. Possible causes for a relatively higher insulin requirement of the frog include (1) an increase in the carbohydrate load on the islets, (2) an increase in the secretion of hyperglycemic hormones, and (3) a higher rate of insulin inactivation.
Target discrimination by the echolocation of bats
Authors: Griffin D. R. , Friend J. H. , Webster F. A. 
Published: June 2005

AbstractMyotis lucifugus first learned to catch mealworms mechanically projected into the air in a laboratory flight room, and were then trained to distinguish mealworms from small metal or plastic disks (3.0 × 12.5 mm and 0.5 × 6.3 mm). These three targets were presented singly in a semi‐random sequence, traveling along very similar trajectories. The most skillful bats caught 98% of the mealworms while avoiding any contact with 85 to 90% of the two types of disks. Echoes of 100–20 kc pulses (similar to the bats' orientation sounds) were measured from all three targets in almost all possible angular orientations. There was great overlap in intensity both in the peak amplitudes and in each of the ten 8 kc bands from 100–20 kc. These bats thus seem capable of some qualitative discrimination based on the “fine structure” of echoes from small moving targets.
An investigation of lactate dehydrogenase activity in early amphibian development
Authors: Adams Ellen , Finnegan Cyril V. 
Published: June 2005

AbstractThe ontogeny of the enzyme LDH has been studied in two species of amphibians (Amblystoma gracile and Rana aurora) as it provides a sensitive gauge of the state of differentiation of the organism, since the number and proportions of LDH isozymes present exhibit temporal and species specificity, thereby reflecting the degree of activity of the controlling genes. The presence of LDH in all stages of both species examined was establishd by assaying embryo homogenates for LDH activity, and the LDH was resolved into isozymic patterns by the methods of starch gels and disc electrophoresis. Specific enzyme activity for each developmental stage was correlated with the developmental events then occurring and the isozyme patterns obtained were discussed in terms of an increase in complexity during Anuran ontogeny while an extension of the current LDH isozyme hypothesis was advanced to account for some of the Urodele experimental findings.
Isozymes of isocitrate dehydrogenase: Subunit structure and intracellular location
Authors: Henderson Nanine S. 
Published: June 2005

AbstractIsocitrate dehydrogenase (IDH) exists in mammalian tissues as three enzymes, one specific for NAD and two specific for NADP. The two NADP isozymes differ in electrophoretic mobility, immunological characteristics, and tissue and subcellular location. ONe is found mainly in the mitochondrial fraction and one in the supernatant fraction of tissue homogenates. Two allelic forms of the supernatant NADP isocitrate dehydrogenase have been described in inbred strains of mice. In a heterozygote containing both alleles, three forms of the supernatant NADP‐IDH are generated in a ratio of 1:2:1. This implies that the supernatant enzyme is a dimer. The mitochondrial form is not affected by the gene, indicating separate genetic control. Liver mitochondria contain both the supernatant and the mitochondrial isozymes. Thus at least one protein found in the mitochondria is encoded in a nuclear gene.
Duration of stimulus and latent periods preceding furrow formation in sand dollar eggs
Authors: Rappaport R. , Ebstein R. P. 
Published: June 2005

AbstractBecause information concerning the time relations of the cleavage stimulus should prove useful in characterizing both the stimulus and the nature of the response in the cell surface, methods were devised for determining how long the surface must be acted upon by the asters to produce a furrow and the duration of the latent period between the end of this stimulus period and appearance of the furrow. Eggs of the sand dollar Echinorachnius parma were used in experiments wherein unstimulated surface was brought close to the interastral zone of the mitotic apparatus for specified periods. Since this modification subjected the cell to physical stress or constraint, several different methods were used. As was anticipated, the times determined differed somewhat according to the method used. Exposure of the surface to the interastral zone for about one minute subsequently produces an active furrow. The latent period between the end of the stimulus period and the appearance of the furrow is about two and one‐half minutes and the total time from the beginning of stimulation to appearance of the furrow is between two and three and one‐half minutes.The mitotic apparatus can repeatedly elicit new furrows within the same cell despite visible loss of distinctness from frequent handling. This suggests that stimulation is accomplished by a fundamentally simple relationship between asters and surface. During the latent period the presumptive furrow area has greater ability to retain its contour despite inncreased tension at the surface than does non‐furrow surface. The undiminished capacity for division that persists in cells subjected to frequent and extensive cytoplasmic shifting which accompanies relocation of the mitotic apparatus by pressure displacement implies that after stimulation, completion of the cleavage process is independent of any specific subsurface cytoplasmic configuration.
Periodic motility of normal and spinal chick embryos between 8 and 17 days of incubation
Authors: Hamburger Viktor , Balaban Martin , Oppenheim Ronald , Wenger Eleanor 
Published: June 2005

AbstractPrevious studies of the spontaneous cyclic motility of the chick embryo were extended to incubation day 17. The activity and inactivity phases of the cycle were recorded on a polygraph, for a 15‐minute observation period. The percentage of time spent in activity rises steadily from less than 10% at the beginning of motility at three and one‐half days to 80% at day 13. This peak is maintained up to day 17; subsequently, motility declines. The mean duration of activity phases increases and that of the inactivity phases decreases until the high plateau is reached, though both values change independently of each other. In order to study the effect of the brain on spontaneous motility, spinal embryos were obtained by extirpation of part of the cervical cord in two‐day embryos. The spinal embryos retain their capacity for cyclic motility. However, the activity is reduced by approximately 10–20% at all stages between the eighth and the seventeenth day. The brain influence asserts itself in a lengthening of the duration of the activity phases and in a shortening of the inactivity phases. An inhibitory effect was not observed at any stage.
The cytological and chemical organization of the prostatic epithelium of Didelphis virginiana Kerr
Authors: Martan Jan , Allen John M. 
Published: June 2005

AbstractThe prostatic complex of Didelphis virginiana Kerr has been studied by a variety of cytological and cytochemical means. Segment I was characterized by an apocrine type secretory mechanism. The apical parts of the epithelial cells, which were shed into the glandular lumen, contained vesicles which give positive cytochemical reactions for acid phosphatase, aliesterase, 5′‐nucleotidase, and nucleoside diphosphatase. These vesicles also contained material which was reactive with the periodic acid‐Schiff test for mucopolysaccharide and Baker's test for phospholipid. Segment II was characterized by the presence of two types of cells in the glandular epithelium. Type A cells contained large rounded secretory granules which gave positive reactions for acid mucopolysaccharides but not for proteins. Type B cells contained large elongate secretory granules which gave positive reactions for proteins but not for polysaccharides. Electronmicrographs indicated these secretory granules to have distinctive morphologies and to contain complex crystalloid material. No cells with characteristics intermediate between those of the A and B types were observed. Segment III of the prostatic complex was characterized by the presence of large amounts of glycogen both in the epithelial cells and within the glandular lumen. These observations indicate a remarkable degree of morphological and biochemical heterogeneity on the part of the prostatic complex of this animal.
Effects of ultraviolet microbeam irradiation on morphogenesis in Euplotes
Authors: Wise Benjamin N. 
Published: June 2005

AbstractDevelopmental mechanisms in Euplotes plumipes were analyzed in terms of theresponse to damage produced by a UV microbeam. Individual animals, representing all stages of the morphogenetic cycle, were irradiated at a variety of cortical sites, including bases of mature cirri and membranelles, primordial structures, and non‐ciliated regions; they were then observed and fixed for silver‐staining.Immediate damage is restricted to cortical and ciliary structures directly irradiated. Irradiated cirri and membranelles, including their associated basal structures (infraciliature), are effectively destroyed after about two minutes exposure to the UV microbeam. Contrary to what might be expected from the reports of earlier workers using microsurgical techniques, no regeneration response ensues following such damage in these animals. Damage to cirri perists until these organelles are replaced during normal pre‐division morphogenesis; damage to adoral membranelles, which are not normally replaced at division, persists indefinitely through succeeding generations of proters. It is concluded that destruction of infraciliary structures does not, in itself, provide a sufficient stimulus to regeneration in Euplotes.Irradiation of either mature or primordial cortical organelles can be effective, however, in causing the temporary arrest of normal pre‐division morphogenesis, including resorption of all primordial stuctures, and the arrest or disappearance of macronuclear replication bands. The probability that resorption will occur depends, in part, on the developmental stage of the structures irradiated: irradiation of primordial structures during early stages induces this response more frequently than does irradiation of late stage primordia or mature organelles. These results are discussed in terms of the functional relationship between infraciliary structures and the mechanisms controlling development.
Inductive tissue interaction in the development of the mouse lens in vitro
Authors: Muthukkaruppan V. 
Published: June 2005

AbstractInductive tissue interaction involved in lens differentiation in the mouse embryo has been studied using millipore filter culture methods. The entire eye rudiment (nine day embryo) comprising optic vesicle, surrounding mesenchyme and overlying ectoderm differentiated in vitro into lens and retina, essentially as in normal development. Individual tissue components of trypsin‐separated lens primordia lost their structural organization when cultured alone, but lens epithelium in combination with mesenchyme was maintained as a vesicle without obvious lens fiber formation. Tissue recombination experiments show that differentiation of lens fibers in the presumptive lens ectoderm as well as in the lens placode depends on the inductive influence of optic cup. This influence can pass through a millipore filter barrier of 25 μ thickness and 0.45 μ porosity. Differentiation of lens fibers in the anterior lens epithelium of later embryos was also dependent on the inductive action of neural retina, suggesting the presence of continued inductive interaction in lens formation. The initial influence of optic vesicle on the presumptive lens ectoderm seems to be critical and of short duration, leading to the formation of a placode which has acquired stabilized lens forming property. Continued realization of this property depends on further inductive action.
Lactate dehydrogenase isozyme patterns of fish
Authors: Markert Clement L. , Faulhaber Ilse 
Published: June 2005

AbstractRepresentatives of 30 species of fish were examined for their content of LDH isozymes. One major isozyme system was found in all fish. In addition, two minor systems restricted to eyes and to gonads were found in many fish. Fish may be classified into four groups on the basis of their possession of one, two, three, or five major isozymes of LDH. The major isozyme patterns can be attributed to the polymers of two protein subunits under the control of two genes, as in mammals and birds, but the variety of heteropolymers produced varies in different species. The fluke and other flatfish are exceptional in that they synthesize only one kind of subunit which polymerizes to form a single variety of LDH. All other fish produced at least two major isozymes presumably the homopolymers of A and B subunits. The three‐isozyme fish produce, in addition, a single heteropolymer. A few fish produce three heteropolymers and two homopolymers to produce the characteristic pattern of five isozymes seen in mammals.In populations of the whiting, which has five major isozymes, two mutant alleles at the B locus were discovered. Each of these alleles produced polypeptides with characteristic electrophoretic mobilities. Consequently, heterozygous individuals contained more than 15 isozymes.A variety of minor isozymes that appear on zymograms may represent modifications of the major isozymes. However, the minor isozyme systems of the gonad and the eye seem to be genetically distinct molecular systems, separate from and in addition to the major isozyme system.
Implantation of ferret ova fertilized by mink sperm
Authors: Chang M. C. 
Published: June 2005

AbstractEpididymal mink (Mustela vison) sperm were inseminated into the uterine horns of ferrets (Mustela furo) at various times before or after ovulation which was induced by intraperitoneal injection of H.C.G. The Fallopian tubes or uterine horns of each animal were examined at different times. The ova were recovered and examined microscopically for the evidence of fertilization at 60–66 hours. Cleavage of ova, blastocyst formation during 4–12 days, and the development of embryos during 22 to 42 days were also ascertained.The fertilization rate is rather low, ranging between 8–41%, probably depending on the number of sperm inseminated and the time of insemination in relation to ovulation. The cleavage rate is lower than either the ferret or mink ova, but no delayed implantation was observed as in the case of the mink. The fertilized ova developed and implanted, but degeneration occurred at various stages, although some of them went to advanced stages.
Influence of the adrenal glands on DNA synthesis in normal and compensating kidneys
Authors: Reiter Russel J. , McCreight Charles E. 
Published: June 2005

AbstractThe role of the adrenal glands in controlling the synthesis of deoxyribonucleic acid in normal and compensating kidneys of rats given saline drinking fluid was studied using tritiated‐thymidine and radioautography. Adrenalectomy alone increased significantly the labeling indices of the renal cortex and medulla of otherwise intact rats.Two days following unilatral nephrectomy of rats with intact adrenal glands, the number of labeled nuclei in the remaining kidney increased by factors of about 4 and 2.5 in the cortex and the medulla, respectively. Adrenalectomy moderately decreased the hyperplastic response of the cortex of the remaining kidney, but increased still further the labeling index of the medulla.By five days after unilateral nephrectomy of rats with intact adrenal glands, neither the cortex nor the medulla of the remaining kidney exhibited a marked hyperplastic response. In adrenalectomized animals, also, unilateral nephrectomy caused only slight increases in the labeling indices of the cortex and the medulla of the remaining kidney.
Alcohol dehydrogenases: A polymorphism in Drosophila melanogaster
Authors: Ursprung Heinrich , Leone Janet 
Published: June 2005

AbstractBy means of a rapid microelectrophoretic technique suitable for single‐fly analysis, two types of alcohol dehydrogenase (ADH) isozyme patterns were found, each true breeding in homozygous stocks. A cross of these two types produces offspring with a third type of ADH pattern, containing hybrid ADH molecules in addition to the parental forms. Various strains were analyzed and found to contain flies of the three ADH types in various proportions indicating different gene frequencies.When octanol was used as a substrate instead of ethanol, an additional isozyme system was found, for which some strains are polymorphic also.The results obtained thus far are consistent with the assumption that ADH in Drosophila is a dimer.
Differentiation of transplanted larval salivary glands of Drosophila hydei in adults of the same species
Authors: Berendes H. D. , Holt Th. K. H. 
Published: June 2005

AbstractSalivary glands implanted in adult milieu without simultaneous implantation of larval ring glands showed further development and differentiation. The development of the glands was tested by thymidine‐H3 and uridine‐H3 incorporation in the chromosomes and by proline‐H3 incorporation in the cytoplasm. Differentiation was evaluated on the basis of the presence or absence of mucopolysaccharide synthesis in the cells.Chromosomal thymidine incorporation was observed to proceed for a longer period in the adult milieu. DNA measurements revealed that at least in some cells of glands which were implanted at a mid third instar stage the level of polyteny is increased to a level which is never reached during normal development.Glands implanted at a mid third instar stage showed chromosomal uridine incorporation until at least 18 days after implantation.Comparison of the chromosomal puffing patterns in normal and implanted glands revealed that the chromosomes are still able to produce specific puffs after at least three weeks of implantation.In general, glands which were implanted at younger stages of normal development showed a higher response to the adult milieu than glands implanted at a stage near to puparium formation. Also the individual cells of implanted glands showed obvious differences in their response to the adult milieu. It was concluded that the growth and differentiation of the gland cells proceeds but that the regulation and coordination of the processes are disturbed in the adult milieu.
Chemical and morphological studies on inorganic phosphate deposits in Rana catesbeiana skin
Authors: Taylor R. E. , Taylor H. C. , Barker S. B. 
Published: June 2005

AbstractSkin from Rana catesbeiana adults and tapoles was found to contain an unusually high concentration of inorganic phosphate which was chemically identified and histologically localized as dense granules of calcium phosphate deposited as a discrete layer at the junction between the stratum spongiosum and the stratum compactum of the dermis. Electron microscopic studies revealed that the granules were composed of fine needle‐like crystals and were not associated with cells which seemed obviously related to their genesis. Although no definite function was established for this apparently normal structure of bullfrog skin, its possible role as a reservoir of readily available calcium was suggested. As such, it would represent an important factor to be considered in studies of the biochemistry and physiology of frog skin, especially those which deal with the effects of calcium depletion.