bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effects of nerve growth factor on the spinal ganglia of Ambystoma maculatum
Authors: Weis Judith Shulman 
Published: June 2005

AbstractNerve growth factor (NGF) isolated from mouse submaxillary glands was injected three times weekly into late embryos and young larvae of Ambystoma maculatum for a period of three weeks, producing an enlargement of the spinal ganglia owing to hyperplasia. This hyperplasia corresponds to the method of normal growth of ganglia at this late embryonic period of development, which is similarly one of cell multiplication rather than cell enlargement. The response of animals kept in the cold (12°C) during the experimental period, and which had reached Harrison stage 41 by the end of the experiment, was of doubtful significance, contrasted with that of animals maintained at room temperature and which had become 15 mm larvae by the end of the experiment. The latter group showed an increase in ganglion size of 100% over controls. The difference in magnitude of response of the two groups is believed to be due to the existence of a limited period in development when the animal is sensitive to NGF. The slowly developing animals in the cold had probably just reached the sensitive period by the end of the experiment, thus accounting for their small response compared with that of the animals which were allowed to develop further.
The ear of the chameleon: The round window problem.
Authors: Wever Ernest Glen 
Published: June 2005

AbstractAn examination of serial sections of the ears of several specimens of Chamaeleo senegalensis and Chamaeleo quilensis gives support to an earlier suggestion that these ears function by means of a substitute round window. The usual type of round window is absent, but there is a tortuous pathway leading from the scala tympani through the perilymphatic recess and then along the foramen of the glossopharyngeal nerve to the air cavity of the middle ear.This pathway makes possible a mobilization of the cochlear fluids in response to sound pressures exerted at the oval window by the columellar footplate. However, the mechanism is somewhat inefficient; the frictional resistance along the pathway reduces the amplitude of cochlear motion. The relatively poor sensitivity of these chameleon ears is thus largely accounted for.
Aster‐equatorial surface relations and furrow establishment.
Authors: Rappaport R. 
Published: June 2005

AbstractFlattened eggs of the sea urchin Hemicentrotus pulcherrimus were used in experiments designed to determine whether furrow establishment depends upon any particular geometrical relationship between the asters and the equatorial surface. In normal eggs at first cleavage the asters are 29.5 μ apart and the distance from the spindle center to the equatorial surface is 47.3 μ. In flattened eggs, the mitotic apparatus was pushed to an excentric position. The maximum spindle‐to‐surface distance that permitted furrowing was 62.5 μ. At second cleavage the spindle‐to‐surface distance is normally 36.2 μ but furrows develop when the distance is as great as 47.5 μ. The interastral distance and spindle‐to‐surface distance were varied simultaneously in flattened, dispermic eggs containing four asters. The activity of supernumary sperm asters was not detectably different from that of the mitotic apparatus. If the interastral distance was 32.5 μ furrows formed when the spindle‐to‐surface distance was between 32.5 μ and 47.5 μ. When the interastral distance is increased to 35 μ or more at the same spindle‐to‐surface distances, furrowing was rare. Very short spindle‐to‐surface distances were produced by perforating the flattened cells. They allowed study of combinations involving large interastral distances and short spindle‐to‐surface distances. Under this circumstance asters 35 μ or farther apart invariably elicited furrows when the spindle‐to‐surface distance was 20 μ or less. Decreasing the spindle‐to‐surface distance remedies a deficiency occasioned by abnormally great interastral distances. These results are considered to support the view that furrow establishment requires conjoint action of a pair of asters upon equatorial cell surface.
Some aspects of tail regeneration in the lizard, Anolis carolinensis. II. The role of the peripheral nerves,
Authors: Cox Prentiss G. 
Published: June 2005

AbstractThe work reported here affirms that the ependyma supports tail regeneration and demonstrates that the peripheral nerve supply makes no essential contribution to the regenerative process. The normal peripheral nerve supply in the tail of Anolis carolinensis was found to be 4.5 fibers per (100 μ)2. In tails in which the peripheral nerve supply was reduced to 0.34 fibers per (100 μ)2 normal regeneration occurred if the ependyma was present. In the absence of the ependyma (i.e., the central nervous system) but with 50–75% of the peripheral nerves present no normal regenerative outgrowth occurred; however, three or four myomeres were regenerated.
Adenosine deaminase phenotypes among sexual and parthenogenetic lizards in the genus Cnemidophorus (teiidae)
Authors: Neaves William B. 
Published: June 2005

AbstractElectrophoresis of liver homogenates has revealed distinct adenosine deaminase (ADA) phenotypes in each of four sexual species belonging to the Cnemidophorus sexlineatus group. A fifth sexual species, C. tigris, shares one of these phenotypes with a species of the C. sexlineatus group, but is distinguished from this species by other genetic and biochemical characters. Hence, knowledge of ADA phenotypes permits discrimination among each of the five sexual species suspected of involvement in interspecific hybridizations leading to the origin of parthenogenetic Cnemidophorus species. Combinations of two or three ADA phenotypes characteristic of sexual species are found in each parthenogenetic species studied. This finding supports the theory of hybrid origin of parthenogenetic species, while the combination of particular alleles in each parthenogenone permits the implication of specific sexual species in its origin.
Photoperiodic control of antler cycles in deer. II. Alterations in amplitude
Authors: Goss Richard J. 
Published: June 2005

AbstractDeer native to temperate zones grow new antlers each year in synchrony with the annual photoperiodic cycle. When the amplitude of this cycle is reduced from normal winter and summer solstices (at 42° latitude) of nine and fifteen hours to as little as eleven and one‐half and twelve and one‐half hours (equivalent to about 9° latitude), sika deer still tend to grow antlers on schedule, even when that schedule is accelerated.Deer exposed to days of constant length for prolonged periods of time fail to replace their antlers when the light:dark ratio is 12L/12D. When held on unchanging short (8L/16D) or long (16/8D; 24L/OD) days, however, they continue with their antler cycles at irregular intervals averaging about 85% of the siderial year.These results are interpreted in terms of an inherent circannian rhythm, the duration of which can be adapted to the frequency of the prevailing photoperiodicity, but which reverts to approximately a year on constant long or short days and disappears altogether on simulated equatorial photoperiods.
Acid mucopolysaccharide changes in chick hatching muscle
Authors: Klicka John , Edstrom Ronald , Ungar Frank 
Published: June 2005

AbstractAcid mucopolysaccharide levels in the Musculus complexus (hatching muscle) of the chick embryo progressively increase during the final 96 hours of incubation with the most marked increase occurring on the day of pipping. The significance of these changes in relation to the role this muscle plays in the hatching process remains obscure, but it is suggested that the mucopolysaccharides, together with the large amount of water simultaneously taken up by this tissue, form a spongy muscle mass which serves to cushion the skull when force is applied to the shell during pipping.
Phenogenetics of the eyeless‐Dominant mutant of Drosophila melanogaster. I. Development of the lethal larvae,
Authors: Arking Robert 
Published: June 2005

AbstractThe causal mechanisms underlying the lethality of the eyD lethal homozygotes of D. melanogaster were studied. The phenocritical phase occurred at the onset of metamorphosis. Non‐pupating larvae remained in the third instar for periods of time ranging up to 120 hours after their normal sibs had pupated. By this time they had either died as arrested third instar larvae or else underwent a delayed pupation and then died. No “fourth instar” larvae were observed. Those lethals that did pupate died at a mean gonadal developmental age of 20–36 hours. A distinctive syndrome of morphological abnormalities, characteristic of an aphasic development, was found in the non‐eclosed pupae. Paraldehyde fuchsin staining of normal and lethal animals has indicated that the release of the neurosecretory substances in the lethals may be delayed for at least 36 hours following pupation. Injection of approximately 0.07 μg of α‐ecdysone enabled 94% of the non‐pupating larvae, arrested at the third instar for 72–84 hours after their normal sibs had pupated, to resume development and enter the prepupal or pupal stages. It is suggested that the eyD mutation most likely exerts its lethal effect by adversely affecting the ecdysone titer, thereby creating a hormonal imbalance with manifold effects on the developmental process.
The ear of the chameleon: Chamaeleo höhnelii and Chamaeleo jacksoni
Authors: Wever Ernest Glen 
Published: June 2005

AbstractThe study of the chameleon ear that began with Chamaeleo senegalensis and Chamaeleo quilensis has now been extended to two further species, Chamaeleo höhnelii and Chameleo jacksoni, with results that are different in important respects. As measured in terms of cochlear potentials, the two species of the present study show definitely poorer sensitivity to aerial sounds. Also their responsiveness to these sounds is not made much worse by severing the columella, an observation that stands in contrast with the serious impairment that this operation produces in C. senegalensis and C. quilensis.The explanation lies in a difference between the sound receptive mechanisms in the two groups. In the species examined earlier a substitute tympanic membrane was found: beneath the surface at the side of the head is a diaphragm formed by a thin plate of the pterygoid bone and a membrane extending its surface to the border of the quadrate bone. In addition there is a branch process (anterior process) of the extracolumella that attaches to the middle of this pterygoid plate, and transmits the movements made by the plate in response to sounds to the stapedial footplate in the oval window. In C. höhnelii and C. jacksoni this anterior process is lacking, and the pterygoid plate cannot function as a sound receptive surface.
Metamorphosis of imaginal disks of the housefly: Evagination of transplanted disks
Authors: Bhaskaran G. , Sivasubramanian P. 
Published: June 2005

AbstractA new technique for transplanting imaginal disks of the housefly is described. When prepupal disks are transplanted superficially (surface transplantation) just beneath the puparium in early prepupal hosts, they evaginate synchronously with the host's organs and differentiate normally like the disks developing in situ. Histological evidence indicates that cells from the peripheral region of the disks migrate and join the epidermis of the host. This facilitates continuation of morphogenetic events culminating in eversion of the transplant. The significance of the cellular contact with epidermal cells of the host is discussed.A well developed nerve from the transplanted leg joins the thoraco‐abdominal ganglion of the host. Flexion of the terminal leg segments indicates the presence of motor fibers innervating muscles in the leg.Disks from late third instar larvae and young prepupae evaginate whereas disks from younger third instar larvae fail to evaginate when surface transplanted. Disks, from all types of donors, cultured in adult abdomens fail to evaginate when retransplanted in prepupae. These and other results suggest that hormones may induce or inhibit morphogenetic cell movement in imaginal disks.
Postural control of shell position by the abdomen of the hermit crab, Pagurus pollicarus. I. Morphology of the superficial muscles and their nerves
Authors: Chapple William D. 
Published: June 2005

AbstractAs in other decapod crustacea, the muscles of the hermit crab abdomen are divided into a central mass of muscle, active during the escape response, and a superficial layer of muscles which is responsible for the normal postural movements of the abdomen. The ventral superficial muscles consist of three layers, a mesial layer of longitudinal fibers, and two distal layers of circular muscle. The longitudinal muscles are thicker on the right side and are divided into three longitudinal strips each innervated by a single excitor motoneuron. Six motor axons innervate the ventral superficial muscles on each side — those on the right are larger than those on the left. Also occurring in the third ganglionic root is a group of fine axons believed to be branches of the motoneurons. There does not appear to be any relationship between the size of the motoneuron and the amount of muscle innervated.
Neurotrophic dependence of the lateral‐line sensory organs of the newt, Triturus viridescens
Authors: Jones Dorothy P. , Singer Marcus 
Published: June 2005

AbstractThe neurotrophic influence on the morphological maintenance of the lateral‐line sensory organs has been studied in the adult newt, Triturus viridescens, under various conditions of denervation. Results show little if any atrophic and degenerative changes during two months following resection of the lateral‐line nerve or the incident spinal nerves. However, if both are destroyed, thus rendering the total environs of the organs nerveless, atrophy and degeneration are advanced within a two‐month period and, indeed, are evident within three weeks. The results favor the idea of neurotrophic control of the lateral‐line sensory organs in amphibians. The results are discussed against the background of past controversies and speculations on the neurotrophic phenomenon. Various control experiments including heterotopic transplantation of the sensory organs are also reported.
Temporal changes in protein synthesis by mouse blastocysts transferred to ovariectomized recipients
Authors: Weitlauf Harry M. 
Published: June 2005

AbstractProtein synthesis in mouse blastocysts, as inferred from the incorporation of 35S methionine in vivo, begins on day 5 of pregnancy (day 1 = the day of vaginal plug formation). The activation of protein synthesis is hormone dependent and does not occur in the absence of either estrogen or progesterone. However, previously stimulated eggs are capable of incorporating 35S methionine immediately after being transferred to ovariectomized recipients. The hormones may affect the blastocysts in two possible ways: (1) they may be responsible for the initial activation and thereafter have little or no effect; or (2) they may be necessary to both activate the blastocysts and to maintain them in an active state.To determine which of these possibilities is correct active blastocysts were recovered from intact donors on day 5 of pregnancy and transferred to the uteri of ovariectomized females. 35S methionine was given at progressively longer intervals thereafter and the blastocysts were recovered and prepared for radioautography.It was found that 35S methionine incorporation by the blastocysts decreased and finally stopped after prolonged exposure to the uteri of ovariectomized recipients. The depression was not caused by damage to the embryos; rather they simply became dormant.
On the application of immunological techniques in geographic group studies of Atlantic sea herring, Clupea harengus II. Herring serum analysis by gel diffusion
Authors: DiCapua Richard A. 
Published: June 2005

AbstractThe sera of Atlantic sea herring, collected from 13 contiguous oceanic locations, were assayed by gel (double) diffusion for precipitinogen differences. An immune serum (rabbit) against the sera of each location was required. Gel diffusion patterns characteristic of specific geographic origins of herring sera were not detected. Immune serum aliquots were therefore individually neutralized with one of a series of dilutions of herring serum from the various geographic locations prior to diffusion (the use of undiluted serum results in complete precipitin neutralization regardless of its origin). The neutralization capacity of origin‐separate precipitinogens appears to be related to the geographical distance separating the origins of immunizing and neutralizing sera. Sera of unknown origins, providing they originate from the overall area sampled, can be related to sera of specific origins by comparison of their neutralization capacities. The gel diffusion results are in agreement with previously reported immunoelectrophoretic data (DiCapua, 1966) and are consistent regardless of sex, pool size constituting the sample or collection date. The serological relationship of the five dominant clupeoid species is examined.
An electron microscopic study of chordamesoderm‐neurectoderm association in gastrulae of a toad, Xenopus laevis
Authors: Kelley Robert O. 
Published: June 2005

AbstractGastrulae from South African Clawed Toads, Xenopus laevis, were fixed in phosphate buffered glutaraldehyde, postfixed with Os O4 and prepared for electron microscopy. Mesodermal cells did not contact cells of the ectodermal layer. Furthermore, unexpected quantities of extracellular material filled the space between layers during early stages of gastrulation. Extracellular material consisted of glycogen, ribonucleoprotein particles, and fibrillar material, similar to material present in lobes of mesodermal cells during the first half of gastrulation. Mesodermal lobes and extracellular materials were also present in ectodermal sandwiches incubated with mesoderm for three hours, but were absent in explants cultured less than three hours. Extracellular materials were also absent in ectodermal sandwiches cultured with presumptive epidermis (non‐inducing cells) for three hours. Ectodermal cells appear to incorporate fibrillar material from the interspace by pinocytosis during late stages of gastrulation. Autoradiographs suggest that labeled RNA is not transferred to ectoderm during gastrulation, but is involved in protein synthesis within mesodermal cells. The product of this synthesis might be visualized as extracellular fibrillar material.
An immunochemical study of the surfaces of sponge cells
Authors: Maclennan Alastair P. 
Published: June 2005

AbstractCells from sponges of six different species when injected into rabbits induced the formation of specific agglutinating antibodies. Cells of each species were shown by cross‐agglutination and cross‐absorption tests to possess species‐specific antigenic determinants on their surfaces, and the observed cross reactions between species were in general accord with taxonomic relationships ascribed on more conventional criteria. Preparations containing complex heteropolysaccharides together with peptide were obtained by extraction of sponges with trichloroacetic acid and were shown to possess the serological specificities of the sponge cell surfaces. These preparations, from each of the six species, sensitized fowl erythrocytes to agglutination by homologous sponge cell antisera. The titers of cross hemagglutination obtained with an individual antiserum and variously sensitized erythrocytes were paralleled by the titers obtained in direct agglutination of sponge cells, indicating that the antigenic groups responsible for hemagglutination were similar to those present on the sponge cell surface and dominating its serological reactions. The isolated polysaccharide‐containing substances precipitated agglutinating antibodies and were themselves antigenic in rabbits. Chemical and serological analysis of a purified polysaccharide obtained from crude material by ion‐exchange chromatography, together with other lines of evidence, suggested that carbohydrate rather than peptide antigenic specificities underlay the serological behaviour of the sponge cell surface.The cell surface specificities detected serologically appeared not to be due to sensitization of sponge cells by intracellular substances liberated during the preparation of cell suspensions from intact sponge. Certain pairs of the sponges examined showed specific cellular reaggregation but the species specificity exhibited did not correlate in any simple manner with the demonstrated antigenic relationships of the species. The serological results are discussed in relation to the various postulated mechanisms of specific reaggregation.
Nucleic acid synthesis in preimplantation rabbit embryos. I. Quantitative aspects, relationship to early morphogenesis and protein synthesis
Authors: Manes Cole 
Published: June 2005

AbstractThe ability of rabbit embryos to incorporate tritiated uridine and thymidine into acid‐insoluble material in vitro has been quantitated by liquid scintillation counting at daily intervals throughout the preimplantation period. The ribonucleic acid content of the embryos has been determined by the orcinol reaction. It is shown that, in spite of a low level of Actinomycin D‐sensitive uridine incorporation during cleavage, there is no net synthesis of ribonucleic acid until immediately prior to blastocyst formation. The acceleration of ribonucleic acid synthesis which occurs at that time precedes, by some 36 hours, the acceleration of protein synthesis. This finding is discussed from the standpoint of genetic expression in the preimplantation rabbit embryo, and with reference to the possibilities for post‐transcriptional control of protein synthesis.
The implantation of blastocysts in the Russian steppe lemming (Lagurus lagurus)
Authors: Aldeen K. Mohi , Finn C. A. 
Published: June 2005

AbstractImplantation in the lemming occurs between the sixth and seventh days of pregnancy and is accompanied by decidualization of the stroma. The blastocyst appears to pass through the epithelium as in interstitial implantation. Alkaline phosphatase is present in the stroma along the length of the uterus before the start of implantation but becomes more intense in decidualized areas following attachment of the blastocyst.Blastocytes do not implant if animals are ovariectomized on the fourth day of pregnancy and progesterone alone is given but will implant if a small amount of oestradiol is given in addition to progesterone.A decidual cell reaction can be induced by the intrauterine injection of oil into animals mated with a vasectomized male; this reaction always occurs on the antimesometrial side of the uterus.