bluuebunny/crossref_metadata_2025_split huggingface dataset:
Further studies on the induction of tolerance of skin homografts in rats
Authors: Silvers Willys K. , Billingham R. E. 
Published: June 2005

AbstractWith the BN → Lewis rat strain combination it has been shown that the median survival time of skin homografts on three‐day‐old hosts (10.0 ± 0.5 days) does not differ significantly from that of similar grafts on adult animals. This rapid attainment of immunologic maturity has provided the basis for a sensitive test for the induction of tolerance of skin homografts. The putative tolerance‐conferring stimulus is injected intravenously at birth and the hosts are challenged with donor strain skin three days later. With this system it has been found that whereas an inoculum of 100,000 bone marrow cells elicited weak sensitization, as evidenced by a significant curtailment of graft survival, increasing the dosage to one million or more cells induced tolerance, as shown by prolongation of graft survival. The proportion of hosts displaying tolerance and its degree, increased with the cell dosage. When test‐grafting with skin was delayed until the hosts were 50–60 days old, the minimal number of cells required to confer tolerance was seven million.With the present assay it has been shown that the tolerance induced by low dosage cellular inocula wanes fairly rapidly, though the presence of a skin homograft from the third day onwards may prolong its duration.A previous finding that, with the present strain combination, bone marrow cells are significantly superior to either spleen or lymph node cells in conferring tolerance of skin homografts has been confirmed. It has been shown that adult thymocytes are only capable of inducing feeble degrees of tolerance over a wide dosage range (5 ‐ 50 × 106) and that thymocytes from infant donors are ineffective.Viable suspensions of epidermal cells and x‐irradiated or frozen‐thawed suspensions of bone marrow cells failed to confer tolerance, though it was induced fitfully by means of a microsomal lipoprotein extract of BN lymphoid tissue.Finally, it was shown that the survival of BN test grafts on three‐day‐old Lewis hosts was significantly prolonged if they were born of Lewis mothers specifically presensitized against BN antigens. This constitutes evidence of a passive transfer of the isoantibodies responsible for the phenomenon of immunological enhancement.
A biochemical study of the growth of Drosophila melanogaster
Authors: Church Robert B. , Robertson Forbes W. 
Published: June 2005

Abstract1. The growth of a wild strain of Drosophila melanogaster has been studied from the time of hatching from the egg to the adult. Wet and dry weights, protein and protein fractions, lipids, RNA and DNA have been determined at successive intervals. 2. All estimates have been carried out on animals grown axenically on defined medium. The medium has been shown to permit growth which is as fast as on live yeast medium when the larvae can burrow freely. 3. Insoluble protein and chitin nitrogen reach a maximum of about 70% total nitrogen in the late pupa, at which time the soluble nitrogen reaches its lowest level. The amino acid fraction reaches a maximum in the early third instar. 4. The water content declines from 70–75% of the live weight at the end of the first instar, rises to a maximum during the second instar and declines sharply to about 66% at the prepupal stage. 5. Total lipids represent an increasing proportion of body weight during larval growth, increasing from about 6% in young larvae to about 15% at pupation. 6. The curve of RNA increase follows the dry weight and protein curves during larval life. The ratio of RNA to protein declines during the first two instars. 7. The increase in DNA content follows a path similar to that of RNA. The RNA/DNA ratio reaches a maximum 24 hours after hatching from the egg, declines to about half this value by 84 hours, and remains more or less constant thereafter. 8. The rates of increase of protein, RNA and DNA during successive periods of larval life show striking differences. For protein the rate is high and increasing until about 36 hours after which it declines rapidly during the rest of larval life. For both nucleic acids the rate of increase falls to a minimum in the early third instar, about the time of the critical size, then increases during proliferation of the imaginal discs and finally declines at the end of larval life. 8. The data are compared with evidence from other strains of Drosophila and from other species of insect. In the latter case, it appears that all the Diptera, so far examined, follow a similar trend in the increase of the nucleic acids during growth. 9. RNA synthesis has been followed during development from egg to adult with the aid of pulse‐labeling and sucrose gradient analysis. Developmental stages differ in the amount of rapidly labeled high molecular weight material which is most evident in newly hatched larvae and in mid‐third instar larvae, at times when the rate of synthesis of total RNA is high.
A study of DNA synthesis during the transformation of the Iris into lens in the lentectomized newt
Authors: Eisenberg Sara , Yamada Tuneo 
Published: June 2005

AbstractAn autoradiographic study of the pattern of DNA synthesis in Wolffian lens regeneration of adult newt Triturus viridescens was carried out. Animals were injected with thymidine‐H3 at different stages of lens regeneration, and killed after different time intervals ranging between 2 hours to 15 days. The temporal pattern of incorporation and localization of labeled cells was studied with autoradiograms.DNA synthesis, which is not detectable in the normal iris, is activated in the dorsal as well as in the ventral iris within five days after lens removal when the cells are still heavily pigmented. When the dorsal iris cells become depigmented, all depigmented cells show a high labeling frequency. Cessation of DNA synthesis is indicated immediately before the depigmented cells start to elongate and differentiate into fibers. At later stages of regeneration, when the regenerate is composed of fibers, lens epithelium, and stalk, DNA synthesis is limited to the latter two. It has been pointed out that cells synthesizing a detectable amount of gamma crystallins never synthesize DNA.The data suggest that all the cells which form the new lens pass through a period of DNA synthesis, which starts approximately five days following lens removal. However, not all cells which are activated to DNA synthesis participate in lens formation. Thus, DNA synthesis is a necessary but not sufficient condition for transformation of iris cells into the lens cells.
Tissue transplantation immunity in the adult newt, Diemictylus viridescens. III. The effects of X‐irradiation and temperature on the allograft reaction
Authors: Cohen Nicholas 
Published: June 2005

AbstractGraded dosages of x‐irradiation from 500r to 3000r inhibited destruction of Diemictylus viridescens allografts at 23 ± 0.5°C for at least as long as the survival time of the hosts (up to 35 days). Lymphocytes were observed in 20% of the grafts whose hosts received 500r and 1000r but they were present in far weaker concentrations than seen in any control grafts at all stages of rejection. No lymphocytes were evident in any grafts on hosts irradiated with 1500r, 2000r, and 3000r.The effects of various temperatures on allograft rejection in the newt were also examined. There was no difference in the mean survival times of grafts maintained at 30°C and 23°C. At 20°C, however, hemostasis and hemorrhaging were significantly delayed by a factor of 1.6 and 1.7 times, respectively, when compared with the findings at 23°C. At 10–15°C, no hemostasis or hemorrhaging were displayed for 191 days after transplantation. Lymphocytes, however, were apparent in very low concentrations in the tissues of some of the grafts and localized destruction of a few melanophores were noted. Two grafts maintained at 10–15°C for 155 days and then transferred to 20°C were completely destroyed within 36 days. This destruction was more rapid than for grafts initially maintained at 20°C.
Osmotic hemolysis of the camel's erythrocytes. I. A microcinematographic study
Authors: Perk K. 
Published: June 2005

AbstractGradual osmotic hemolysis of camel erythrocytes was observed by means of phase contrast microscopy and recorded by microcinematographic methods. It was found that the normal ovoid erythrocytes become spherical when the solution surrounding the erythrocytes is diluted ionically, and they swell to 240% of the initial volume. After hemolysis the erythrocyte membranes (ghosts) revert to their original oval form.Comparative studies of osmotic fragility tests on red blood cells of growing and adult camels showed the presence of two distinct cell populations in growing camels. One corresponds to the adult blood. The second cell type is more resistant to osmotic pressure and is found only in the young camel.
An investigation recording all salamanders which can and cannot regenerate a lens from the dorsal iris
Authors: Stone L. S. 
Published: June 2005

AbstractA brief description of lens regeneration is given of all the 21 salamanders which can regenerate a lens from the dorsal iris after lentectomy. Illustrations of all but one are shown, 18 of which are from eyes of species which were lentectomized by the author. Eleven species of salamanders are American, eight are European and two are Japanese. Table 1 lists all of the 21 species of salamanders representing different genera which regenerate a lens and all of the eight species, also of different genera, which fail to regenerate a lens.All members of the genus Triturus so far examined regenerate a lens and all of the Amblystomidae which have been tested do not. One species of the genus Eurycea regenerates a lens while another in the same genus does not. It is suggested that hybridization might be attempted between two similar closely related species for an examination of the ability of lens regeneration in the offspring.Since there are more species of salamanders distributed over the American continent than in any other part of the world there is an unique opportunity to discover how widespread this phenomenon is for lens regeneration from the dorsal iris. Methods (table 1) and techniques are described for making serial sections of eyes.
Cell loss in the trochlear nucleus of the chick during normal development and after radical extirpation of the optic vesicle
Authors: Cowan W. M. , Wenger Eleanor 
Published: June 2005

AbstractCounts have been made of the number of cells in the trochlear nucleus in a series of 22 normal chicks between the ninth day of incubation and the seventy‐fifth day after hatching, and in seven animals in which the optic vesicle and adjoining mesoderm were removed during the second day of incubation. Between the ninth and seventeenth days of incubation the number of cells in the normal trochlear nucleus declines from just under 1400 to a little under 700, indicating a cell loss of approximately 50% over this eight day interval. From the seventeenth day onwards there is a further slight fall to between 500 and 600 cells and this number is maintained into the third month after hatching. Following excision of the optic vesicle there is an earlier, and more severe, loss of neurons in the trochlear center, the number of cells being reduced to just under 1000 at the eleventh day of incubation and falling to just over 300 by the sixth day after hatching. Despite this marked cell loss, at no stage is there any gross evidence of neuronal disintegration or phagocytosis. The possible factors responsible for the normally occurring cell loss and for the hypoplasia in the trochlear nucleus after removal of the optic vesicle are discussed.
The eye and skeletal effects of two mutant alleles at the microphthalmia locus of Mus musculus
Authors: Packer Susan O. 
Published: June 2005

AbstractThe mi/mi mouse has a severe microphthalmia, its skeleton shows an almost complete absence of secondary bone resorption, and its eyes and hair have no pigment. The Miwh/Miwh mouse is white with a reduced eye size.The mi/mi eye was first distinguished during the tenth day of embryonic development by an abnormally thick pigment layer and a weakly invaginated optic cup. These abnormalities persisted in the older embryos. Normal closure of the mutant choroid fissure was prevented by the inversion of the pigment layer in this region. An eversion of the nervous retina and derangement of the pigment layer were observed in the Miwh/Miwh eye during the eleventh day of development. These abnormalities led to the formation of a typical coloboma. Subsequent abnormalities of the mi/mi and Miwh/Miwh eyes were attributable to the colobomata and the consequent lack of intraocular pressure. Counts of mitoses in the pigment and nervous layers of the optic cups showed that there were increased numbers of mitoses in the pigment layers of both the mi/mi and Miwh/Miwh eyes.The mi/mi osteoclasts were almost uniformly small and rounded and had significantly fewer nuclei than the large, irregular, multinucleated normal osteoclasts. Osteoclast counts indicated that the mutant parietal bone is not deficient in osteoclasts and may have higher than normal numbers. Mutant osteoclasts were not abnormal in the appearance of their nuclei, frequency of occurrence of cytoplasmic vacuoles, or amount of cytoplasmic basophilia, RNA, or foaminess. While normal osteoclasts contained essentially no glycogen, mi/mi osteoclasts contained, as a group, large amounts of glycogen.
Hypophysectomy and forelimb regeneration in Ambystoma opacum larvae
Authors: Liversage Richard A. 
Published: June 2005

AbstractLarvae of Ambystoma opacum ranging in length from 25–56 mm were included in this work, which was designed to determine the effects of hypophysectomy upon the initiation and continuation of regenerative processes in forelimbs. Included in this work are 111 forelimbs from 92 larvae which comprise three experimental, one sham control and one normal control series.Attention was drawn to a possible relationship between the hypophysis and forelimb regeneration and whether the presence of the pituitary is essential for limb regeneration in this larva. In this approach, hypophysectomy was followed by either immediate amputation or by a recuperation period (which varied in length depending upon the experimental procedure) before the forelimb was amputated. In the latter approach, a recovery period was considered necessary in order to eliminate the possibility of residual pituitary hormones (remaining in the animal for short periods following hypophysectomy) having an influence upon the various target endocrine organs and, ultimately, the regeneration of the forelimb.The results from this investigation show that the presence of the pituitary is not prerequisite for larval forelimb regeneration nor for the survival of the animal. In addition, growth and development of the experimental larvae continued and appeared normal, compared to control animals, up to the beginning of metamorphosis. All hypophysectomized larvae died, however, as metamorphosis began indicating that various pituitary‐endocrine interrelationships are essential for metamorphosis.
In vitro differentiation of tooth rudiments of embryonic mice. I. Transfilter interaction of embryonic incisor tissues
Authors: Koch William E. 
Published: June 2005

AbstractThe mandibular incisor rudiment of the 16 day mouse embryo may be separated by enzymatic treatment into an epithelial covering and an inner mesenchymal papilla. Each separated tissue fails to differentiate when grown singly in vitro, but odontocytes, amelocytes, and their extracellular matrices are noted in cultures of recombined tissues. Separated tissues also fail to differentiate on collagen gels. Both the mesenchymal papilla and the internal dental epithelium differentiate when placed on opposite sides of a Millipore membrane. Cultures of 11 days growth show odontocytes with deposited alcian blue positive matrix; this matrix is found both within and on the surface of the membrane. Amelocytes deposit eosin‐positive extracellular matrix onto the filter surface. Calcification of odontocyte‐deposited matrix, similar to that of dentinal matrix of neonatal incisors, is shown by staining with von Kossa's stain. Transfilter interaction of these embryonic tissues leads, therefore, to their differentiation and deposition of characteristic extracellular matrices.
Sodium fluxes in fresh‐water turtles
Authors: Dunson William A. 
Published: June 2005

AbstractFresh‐water softshell turtles (Trionyx spinifer) showed net uptake of sodium from solutions as dilute as 5 m̈M. Chloride uptake could be accounted for by passive processes. There was no net uptake of potassium. Net sodium uptake was inhibited by low temperatures. Hibernation resulted in decreases in the sodium concentration and osmotic pressure of the plasma.Influx and efflux of sodium in the fresh‐water turtle Pseudemys scripta varied from 0.04 to 10.1 m̈moles/(100 g hour). In hatchling turtles, the exchangeable sodium pool was 96% of the total sodium. The exchangeable pool was subdivided into at least two compartments, one rapidly and the other slowly exchanging. The latter compartment was 19 times larger than the former.Pseudemys scripta, was found to have a system for active uptake of sodium. This involves the membranous lining of the pharynx, the cloacal bursae and the cloaca. Aside from the skin and the shell, these are the only tissues in contact with environmental water. The cloacal region accounted for 48 to 68% of the sodium influx rate.
The central nervous organization underlying control of antagonistic muscles in the crayfish. II. Coding of position by command fibers
Authors: Kennedy Donald , Evoy William H. , Dane Benjamin , Hanawalt Joanna T. 
Published: June 2005

AbstractSingle central interneurons that produce flexion or extension in the crayfish abdomen act in a coordinated fashion upon several ganglia. Each of several elements evoking a similar type of movement has a unique distribution of output to ganglionic centers: thus one of them may produce primarily rostral extension or flexion, another a primarily caudal movement, still another a more general one. Each motor command therefore appears to code for a specific abdominal geometry. Some units produce complex, cyclic motor outflow to postural muscles of the abdomen, or to the appendages.
Antagonism between prolactin and thyroid hormone in amphibian development
Authors: Etkin W. , Gona A. G. 
Published: June 2005

AbstractTadpoles were treated with intraperitoneal injections of mammalian prolactin and growth hormone (NIH). The growth rate of hypophysectomzied tadpoles (R. pipiens) was accelerated by both hormones, prolactin having the greater effect. Metamorphosis in the bullfrog (R. catesbeiana) was inhibited by prolactin but not by growth hormone. The results are interpreted to indicate a general antagonism between prolactin and thyroid hormone in amphibian development with respect to both growth rate and metamorphosis.
Tissue interactions in the development of ptilopody and brachydactyly in the chick embryo
Authors: Goetinck P. F. 
Published: June 2005

AbstractOne of the characteristics of the Brahma breed of chickens is that the scales along the fourth tarsometatarsus and digit IV are replaced by one or more rows of feathers. This triat known as ptilopody is associated with another trait, brachydactyly, a reduction in length of digit IV. The interactions between mesoderm and ectoderm in the development of the two traits were analyzed by recombining mesodermal and ectodermal components of 3‐day‐old Brahma and White Leghorn embryos. Based on the phenotypes of the composite limbs observed at a total age of 17 days, it is concluded that brachydactyly results from an effect of the Brahma genotype on the mesoderm only, while the ptilopody phenotype results from an action of this genotype on both the mesoderm and ectoderm of the limb. With respect to ptilopody, the results are interpreted to mean that the Brahma genotype acts by lowering in the ectoderm the threshold of response to mesodermal feather induction and also by reinforcing the feather inductive capacity of the mesoderm.
An autoradiographic study of the sites of protein synthesis in the epidermis of the Indigo snake (Drymarchon corais couperi)
Authors: Roth Sanford I. , Baden Howard P. 
Published: June 2005

AbstractIn order to delineate more clearly the sites of protein synthesis during the synchronous proliferation of reptilian epidermis, H3‐leucine was injected intradermally into the Indigo snake (Drymarchon corais couperi) at various times in the sloughing cycle. Autoradiograms were made of biopsies, taken during the early and late proliferative stages of the molting cycle. These confirmed morphologic observations (Roth and Jones, '66) that moderate numbers of spinous cells are added to the α‐layer during the resting phase. The number of cells added, and the amount of protein synthesized, reaches a maximum in the midresting phase and then decreases. No synthesis of upper α‐layer, μϵσºζ‐layer or β‐layer proteins occurs during the resting phase. Synthesis of the specialized proteins of the β‐layer, the μϵσºζ‐layer and the upper stratum of the α‐layer occurs during the proliferative phase, after the cells have left the basal layer, (while they represent inner epidermal generation), in contrast to mammalian epidermis in which the fibrous proteins are largely synthesized in the basal layer and the lower‐most spinous cells.
Iodine induction of metamorphosis in Aurelia
Authors: Spangenberg Dorothy Breslin 
Published: June 2005

AbstractExtensive laboratory investigations revealed two factors of primary importance for the initiation of metamorphosis (strobilation) in Aurelia aurita. It was found that sufficient quantities of iodide ions (in the form of either potassium iodide or elemental iodine) must be present for scyphistomae preconditioned at a low temperature to strobilate. The iodide ion requirement represents a very low dosage (1: 108 dilution). Thyroxin, also in very minute quantities, likewise induces strobilation in temperature‐preconditioned Aurelia. This response to thyroxin represents the first clearcut demonstration of a morphogenetic response of a coelenterate to a hormone which is biologically significant in vertebrates.A recommended temperature for preconditioning this Texas strain of Aurelia to strobilate is 19° for at least one month prior to testing. Organisms maintained at 27°C can be induced to strobilate for several months, but they ultimately lose their ability to respond to induction stimuli. A higher test temperature of 27°C does, however, hasten the strobilation of scyphistomae in iodine‐containing media.Other environmental factors i.e., nutrition, and pH and hypotonicity of the medium, were found to be of little importance (within limits) to the mechanisms involved in the induction of strobilation (SI) in these organisms.