bluuebunny/crossref_metadata_2025_split huggingface dataset:
A quantitative comparison of the growth of the embryonic chick tibiotarsus in vivo and in vitro
Authors: Schryver Herbert F. 
Published: June 2005

AbstractThe increase in length, wet weight, dry weight, DNA content and chondroitin sulfate content of the tibiotarsus of the embryonic chick has been compared in vivo and in vitro on a chemically defined medium. Both the rate and magnitude of increase were lower in tibiotarsi in organ culture than those in the whole animal.Comparison of ratios of various growth responses gave some indication of the mode of growth in the two situations. The dry weight/wet weight ratio of tibiotarsi in vivo remained virtually unchanged during the growth period in this study, while the ratio of tibiotarsi in vitro declined continually during the cultivation period. The hydration of skeletal elements growing in culture is probably due to degenerative phenomena. The ratio of dry weight to DNA showed that the cells of tibiotarsi in culture did not synthesize dry matter as rapidly as those in the whole chick. On the other hand, the ratio of chondroitin sulfate to DNA indicated that the cells of tibiotarsi in culture were producing chondroitin sulfate at a rate similar to that in vivo. Furthermore, the proportion of chondroitin sulfate in vitro tended to be greater than in the chick embryo. These findings suggest that the matrix of skeletal elements growing in culture, although chondroitin sulfate rich, may be deficient in one or more matrix components.
Motility in the chick embryo in the absence of sensory input
Authors: Hamburger Viktor , Wenger Eleanor , Oppenheim Ronald 
Published: June 2005

AbstractThe following experiment was designed to test the role of sensory input in the motility of the chick embryo: Complete deafferentation of the leg level was accomplished in 2‐day embryos by extirpation of the dorsal half of the lumbar spinal cord including the precursor cells of spinal ganglia; and simultaneous extirpation of the entire spinal cord in the thoracic level to exclude sensory input from more rostral levels. In control embryos, only the thoracic gap was made. The embryos were reared to eight and one‐half, 11, 13, 15 and 17 days, respectively, and manual recordings were made of the leg motility before the embryos were sacrificed. It had been reported by us that the motility of normal chick embryos is periodic, activity phases alternating with inactivity phases. Both the overall activity, i.e., percent of activity during a standard 15‐minute observation period, and the durations of activity and inactivity phases were found to be the same in experimental embryos and in control embryos with thoracic gaps, at least up to and including 15‐day embryos. Histological checks showed the complete absence of lumbar spinal ganglia in the majority of embryos and, the presence of a few small thoracic ganglia in some cases. All embryos with lumbar ganglia were discarded. The motor roots formed a normal plexus, and the pure motor nerves emerging from it showed a normal peripheral distribution and muscle innervation. It is concluded that the leg motility results from autonomous discharges of the lateral motor or internuncial neurons, and that sensory input is not necessary for the triggering, the maintenance or the periodicity of the leg motility. A sharp decline of motility was observed in 17‐day embryos. A study of the histological condition of the residual spinal cord showed a numerical depletion and partial degeneration of the lateral motor column. This deterioration is considered to be responsible for the functional impairments.The implication of these results for the widespread notion that “self‐stimulation” and similar “experiences” during embryonic development play an important role in the molding of behavior is discussed.
The influence of thyroxine on the normal development of the pancreas in Rana pipiens larvae
Authors: Race James , Robinson C. , Terry Robert J. 
Published: June 2005

AbstractComparative studies were made of the exocrine pancreas in normal, thyroidectomized, and thyroxine treated Rana pipiens tadpoles during various stages of development. The weight of the pancreas as milligram per cent body weight (mg% B.W.) is greatly reduced during both artificially induced and natural metamorphosis. During natural metamorphosis the reduction in mg% B.W. of the pancreas begins in the early larval stages and continues in a consistently decreasing pattern through the final stages with the maximum reduction (69%) occurring by the mid‐larval stages (XVI‐XX).In thyroxine treated tadpoles, reduction in mg% B.W. of the pancreas is directly proportional to hormone concentration and the relative weight of the gland is significantly less than that observed in any of the controls of equivalent limb stages even though the absolute weight of the gland has increased over that of the earliest stages (I–V). The pancreas of the thyroidectomized tadpoles showed no significant difference in mg% B. W. when compared to that of a normal control of equivalent limb stage range. Histological investigation of the pancreas revealed no evidence of widespread cellular necrosis of the exocrine elements. Some acinus disorganization, typified by large spaces in the connective tissues and a syncytial nature of the acinar cell cytoplasm, can be seen in the later stages. A discussion of the possible role of thyroid hormone in the normal development of the pancreas is presented. It is concluded that reduction in the mg% B.W. of the pancreas is a naturally occurring phenomenon during metamorphosis resulting from intestinal evacuation and water loss. The water loss may be influenced and regulated indirectly by thyroxine through an effect on cellular and subcellular membrane permeability.
X‐irradiation of lateral‐line primordia in Amblystoma
Authors: Piatt Jean 
Published: June 2005

AbstractEmbryos of Amblystoma punctatum were x‐irradiated with 500 r to 2,000 r at stages 28–30. A rectangle of ectoderm including postauditory placodal material was transplanted orthotopically from the right side of irradiated embryos to nonirradiated hosts of the same age. Controls consisted of the same operation between non‐irradiated embryos. Animals were studied at stage 46 to determine the effects of irradiation upon development of lateral‐line migratory primordia, nerves and ganglion.The dorsal lateral‐line was most affected by irradiation, averaging approximately 90% less organs and 85% less nerve fibers than normal. Midbody lateral‐line averaged approximately 65% less organs and 55% less nerve fibers. There was no reduction in number of ventral lateral‐line organs and scarcely any in number of nerve fibers. Number of lateralis ganglion cells averaged approximately 62% less than normal. Control animals developed normal numbers of organs and nerve fibers in all three lateral‐lines and showed no appreciable reduction of ganglion cells on the operated side.X‐irradiation affects the migration of lateral‐line primordia as well as the proliferation or maturation of Xth lateralis nerve cells. Normality of the ventral lateral‐line in these experiments requires further investigation.
Effects of hormones on adult frog (Rana pipiens) testes in organ culture
Authors: Basu S. L. , Nandi Jean , Nandi S. 
Published: June 2005

AbstractTestes from adult Rana pipiens were maintained for five days in organ culture in a chemically defined medium consisting of CulturSTAT 199 organics dissolved in amphibian Ringer's solution. Various steroid hormones and vitamins, when added individually to testicular organ cultures, were found to be toxic. Toxicity of these substances was reduced or abolished by the simultaneous addition of protein hormones. Most combinations of protein hormones resulted in improved maintenance of cultured testes over that obtained in hormone‐free media. The combinations FSH + LH, and FSH + LH + insulin + testosterone, resulted in almost complete testicular maintenance in vitro and, in some circumstances, even stimulation of spermatogenesis. However, in no case were secondary spermatocytes maintained in these organ cultures, and spermatogenesis could be stimulated only through the first meiotic division.Testosterone, previously demonstrated in vivo to inhibit spermatogenesis at the secondary spermatogonial level, exerted no such inhibitory action in vitro. At the dose level used, testosterone appeared to have a slightly deleterious, but nonspecific, effect on testicular maintenance.Seasonal variations in the sensitivity of the testis to hormones and other conditions in vitro were noted. Testicular maintenance was relatively poor, even in hormone‐supplemented media, during the period of active spermatogenesis (summer). In contrast, gonadotropin‐induced stimulation of spermatogenesis in vitro occurred only in testes taken from winter frogs, at a time when the testicular epithelium is presumed to be maximally sensitive to gonadotropic action.
An electrophoretic study of proteins in chick embryonic fluids
Authors: Geelhoed Sally E. , Conklin James L. 
Published: June 2005

AbstractThe protein fractions of 7–18 day chick serum, allantoic and amniotic fluid and egg white were demonstrated by acrylamide gel electrophoresis.The similarity in protein fractions suggests that most of the amniotic fluid proteins are derived from egg white while serum contributes most of the allantoic fluid proteins.Several protein fractions which are unique to the respective fluids may be produced by components of the extraembryonic membranes.The nature of the proteins found in both serum and allantoic fluid suggests a selective transfer of protein between the two fluids.
Effect of tetracycline on osteogenesis in vitro
Authors: Saxén Lauri 
Published: June 2005

AbstractThe effect of tetracycline on developing bones was explored in organotypic tissue culture. Such culture conditions proved to be suitable for certain experiments dealing with the “teratogenic” effect of drugs, and the first part of the paper examines the possibilities, limitations and fallacies of this technique.Embryonic mouse bones cultivated in vitro show rapid incorporation of tetracycline, and after 30 minutes of cultivation a definite fluorescence is seen. The drug is incorporated at least into two fractions: one which is rapidly released after the withdrawal of tetracycline and one which remains in the calcium‐containing zones of the bone.Tetracycline in concentrations of the order of 5 μg/ml completely inhibits the elongation of the calcified zone of the bone rudiments and the increase of their total calcium. However, experiments with labeled calcium still show an incorporation in the presence of tetracycline although no cumulative uptake is seen. The results thus indicate the existence of a rapidly incorporated calcium fraction which is independent of tetracycline.The inhibition of calcification is reversible up to some five days of treatment, whereafter a transfer to normal medium does not lead to a recovery, and the mineralization seems to be irreversibly blocked.It is concluded that the results speak in favor of the theory of a direct action of tetracycline on the formations of the bone salts, rather than interference with enzymatic activity dependent on divalent cations.
The intra‐embryonic and extra‐embryonic distribution of hydroxyproline in the hen's egg
Authors: Mottet N. Karle , Hall Harold E. 
Published: June 2005

AbstractRecent modifications in the biochemical method for determining hydroxyproline have improved its accuracy. The increasing use of fibroblasts from chick embryos for production of collagen necessitates the reinvestigation of hydroxyproline production in chick embryos. The levels of proline and free and bound hydroxyproline were determined in embryonated hen eggs by the method of Prockop and Udenfriend. Determinations on the yolk, white, and embryo were done separately. Analysis of specimens taken from the onset of incubation to the thirteenth day of incubation revealed the presence of 20 to 80 μMoles of proline in each compartment throughout the period of study. Free hydroxyproline was present in the yolk and white at a constant low level of less than 1 μMole per egg. Hydroxyproline (total: bound and free) was first detected in five day embryos. By nine days the level was 0.5 μMoles; at 11 days, 1.5 μMoles, and at 13 days, 4.25 μMoles. The increase in hydroxyproline when calculated per milligram of wet weight of embryo approximated a straight line.
The genetic control of sea urchin development: A chromatographic study of protein synthesis in the Arbacia punctulata Embryo
Authors: Ellis Charles H. 
Published: June 2005

AbstractAn analysis of the problem of embryonic differentiation in terms of protein synthesis was carried out in the embryo of Arbacia punctulata. The problem was approached with the technique of ion‐exchange chromatography of the embryonic proteins soluble in 0.5 M sodium chloride. Synthetic activity was measured as the incorporation of radioactive amino acids into protein fractions. It was seen that the complexity of the embryo's protein‐synthetic repertoire increases during early development indicating that differentiation at this level can be detected during early development.The antibiotic Actinomycin‐D was found to inhibit most of the specific protein syntheses during late development, while inhibiting fewer in early development. This indicates that most of the differential changes in early protein‐synthetic profiles occur under control of the readout of the embryo's stable messenger RNA. However, most differential changes associated with later development seem to be under control exerted at the gene level. Both translation‐level and transcription‐level control mechanisms appear to be active simultaneously at the stages of development analyzed.The inhibition of DNA‐dependent RNA synthesis, and of further differentiation beyond blastula, was found to be reversible, even after developmental arrest had occurred. The inhibition of protein synthesis was also reversible on removing embryos from the presence of the antibiotic. Since normal development and normal protein‐synthetic profiles are seen following this release of inhibition, it is concluded that there is no stringent requirement for the gene‐directed synthesis of any specific protein during the first 18 hours of development, in order for normal larval development to occur.
Effect of metopiron (SU‐4885) on luteinizing hormone and corticosteroid‐induced ovulation and spawning in hypophysectomized catfish, Heteropneustes fossilis (Bloch)
Authors: Sundararaj Bangalore I. , Goswami Shashi V. 
Published: June 2005

AbstractExperiments were performed to evaluate the effect of metopiron on luteinizing hormone and corticosteroid‐induced ovulation and spawning in three‐day hypophysectomized gravid catfish, Heteropneustes fossilis. Pretreatment of hypophysectomized gravid females with metopiron greatly attenuates the ovulatory capacity of LH, whereas desoxycorticosterone acetate and hydrocortisone acetate induce ovulation and/or spawning regardless of pretreatment. These findings indicate that LH may not act directly on the ovary but via the interrenal. The possible mechanisms involved are discussed.
An analysis of the chemical control of polarized form in hydra
Authors: Lesh Georgia E. , Burnett Allison L. 
Published: June 2005

AbstractDevelopment and maintenance of polarized form in Hydra is controlled chemically by a diffusible factor, concentrated in, and probably produced by nerves in the hypostomal region of the animal. This polarizing (or inductive) factor may be isolated from tissue homogenates of Hydra. It is recovered from the supernatant fraction after centrifugating the homogenate at 25,000 × G for 50 minutes. Concentrated amounts of the extracted substance induce “heteropolarity” in regenerating annuli of Hydra pirardi. Heteropolarity is expressed through the development of supernumerary tentacles and “head” regions. Over 40 tentacles may be induced in heteropolar individuals, compared to the normal number of eight. The polarizing effect of this material is not species specific; H. viridis, H. littoralis, and H. pirardi contain extractable amounts of the active factor. Heterogeneous invertebrate tissue such as Dugesia extract does not induce heteropolarity. Because the active material is both dialyzable and can be digested by trypsin, it is suggested that it may be a peptide.Although the mechanism of action of the polarizing component has not been fully determined, the active material probably is bound by the tissues of the assay animal during the incubation period. It appears to act by directing the differentiation of interstitial cells. Interstitial cells in the annulus tested probably bind excessive amounts of the inducer and differentiate into nerve cells. Secretion of additional inducer from these nerve centers initiates the heteropolar state. The fact that heteropolar animals possess more extractable material per animal than do normal unipolarized hydra substantiates this conclusion, and suggests that a single inductive substance, varying quantitatively apico‐basally, controls the direction of differentiation of neoblast cells in Hydra.
Studies on the mechanisms of ammonia tolerance of the guano bat
Authors: Studier Eugene H. 
Published: June 2005

AbstractThe ammonia concentrations in many day‐roosts occupied by the guano bat, Tadarida brasiliensis, are frequently high enough to produce respiratory discomfort and distress and sometimes reach levels lethal to humans. Investigations were begun in an attempt to elucidate some of the mechanisms of ammonia tolerance of the guano bat. Initial findings show that the blood pH of the guano bat is 7.66 and remains constant during extended exposure to a high concentration of atmospheric ammonia. The efficiency of respiratory filtration of ammonia was measured by noting the increase above normal in total blood nitrogen and non‐protein nitrogen after exposing the blood in vivo and in vitro to highly ammoniated air. From the difference in these two values the amount of ammonia filtered by the respiratory tract was obtained. At ammonia levels of 3,000 parts per million in the air, the bat removes 30–35% of this noxious gas; thus, the existence of an efficient ammonia filtering system is indicated. The filtering mechanism is probably dependent upon the mucous of the respiratory tract, and the filtering efficiency is a function of its rate of production and chemical nature. The observed in vivo increase in blood non‐protein nitrogen resulting from exposure to highly ammoniated air may be attributed to ammonium ions. Ammonia is exhaled by the guano bat upon its return from highly ammoniated to normal air. Renal excretion of fixed base is probably not an adaptive feature contributing to the high degree of ammonia tolerance exhibited by T. brasiliensis.
Some aspects of sexual polymorphism in Chlorohydra viridissima
Authors: Stagni Anna 
Published: June 2005

AbstractProtracted observations on a wild population of Chlorohydra viridissima revealed a sexual polymorphism, expressed by the occurrence all together of male, female and hermaphrodite specimens. The hermaphrodites were either simultaneous or protandrous or protogynous. Careful culturing of several clones under strictly identical environmental conditions strongly indicated a genetic basis of such differences and suggested a polyfactorial sex‐determining system. Andro‐, medio‐ and gyno‐hermaphrodite clones, which more or less tended to shift towards pure male or pure female sex conditions, were detectable. Andro‐ and gyno‐hermaphrodite clones showed less tendency to become sexual. Such a condition is typical of an “unbalanced hermaphroditism” which serves to maintain the species in a mainly hermaphrodite state.
The role of interstitial cells in the maintenance of hydra. IV. Migration of interstitial cells in homografts and heterografts
Authors: Diehl Fred A. , Burnett Allison L. 
Published: June 2005

AbstractNormal and mustard‐treated halves of Hydra pseudoligactis and Hydra pirardi were grafted in distal‐proximal combinations. In all cases H. pseudoligactis grafted more readily than H. pirardi. Mustard‐treated H. pseudoligactis were grafted to normal H. pseudoligactis after various intervals from the time of treatment. Interstitial cells migrated from the normal portions into treated portions lacking them and within 5 to 10 days the animals appeared normal.Normal portions of H. pseudoligactis and H. pirardi were grafted together and in some cases they remained attached for 60 days. Large numbers of interstitial cells accumulated in each portion, near the graft junction. After 15 days, some of these interstitial cells differentiated into cnidoblasts. Interstitial cells migrated from a normal portion of H. pirardi into a mustard‐treated portion of H. pseudoligactis. Differentiation of interstitial cells into cnidoblasts was observed in the host tissue. In heterografts between normal H. pseudoligactis and mustard‐treated H. pirardi there was no exchange of interstitial cells. There was, however, an accumulation of interstitial cells near the graft junction.In both species successful homografts were made between mustard‐treated portions, indicating that interstitial cells are not required for acceptance of grafts. Grafts between mustard‐treated H. pirardi and mustard‐treated H. pseudoligactis showed less initial acceptance than any of the other groups. The rate of detachment was very high in this group. It was suggested that mustard treatment may inhibit production of substances required for adherence of cells.The results are discussed in terms of possible mechanisms controlling interstitial cell migration, division and differentiation.
Unidirectional mating type changes in individual cells from selfing cultures of Paramecium aurelia
Authors: Taub Stephan R. 
Published: June 2005

AbstractIndividual cells participating in mating reactions in selfing cultures of syngen 7, P. aurelia, were isolated and tested to ascertain the mating type they were expressing at the time of isolation and the mating type they were expressing several hours later. In this way a number of cases were discovered in which cells initially expressing mating type XIII had changed to type XIV A transient, hermaphrotypic stage may be involved in this change. The possible significance of these observations is discussed with regard to the process of mating type expression.
Influence of monovalent cations on the growth of Hydra littoralis
Authors: Lenhoff Howard M. 
Published: June 2005

AbstractLi+, Cs+, Rb+, and K+ inhibit the clonal growth rate of Hydra littoralis and, depending upon conditions, can be toxic to the animals. These effects are counteracted by increasing the concentration of Na+ in the environment. In contrast to its inhibitory effect, K+, when in the presence of high concentrations of Na+, increases the growth rate of hydra significantly. Choline and histidine also increase the growth rate, but to a lesser extent. Various combinations of the monovalent ions lead to specific structural and behavioral changes in the animals.
Nutritional requirements for the realization of regulative (repair) capacities of young chick blastoderms
Authors: Spratt Nelson T. , Haas H. 
Published: June 2005

AbstractStudies of the regulative (repair) capacities of young chick blastoderms in ovo and explanted in vitro on culture media varying in their growth promoting properties clearly indicate that these capacities are realized fully only under the most optimal nutrient conditions. Thus the ability of an explanted part of a young blastoderm to form a bilaterally symmetrical embryo body depends not only on the region of the blastoderm isolated, on its intrinsic growth potentiality and on its size (cell number) but also on the growth promoting properties of the culture medium. Realization of regulative potentiality goes hand‐in‐hand with realization of growth (or other synthetic) potentiality.