bluuebunny/crossref_metadata_2025_split huggingface dataset:
Alterations in the developmental properties of stroma during the development of the urogenital ridge into ductus deferens and uterus in embryonic and neonatal mice
Authors: Cunha Gerald R. 
Published: June 2005

AbstractThe ability of mesenchyme from the urogenital ridge to participate in the development of male and female urogenital organs was studied by preparing homo‐and heterotypic recombinants of epithelium and stroma from ductus deferens and uterus of neonatal mice. The recombinants as well as intact 14‐day old embryonic urogenital ridges (UGR) were grown for two to eight weeks in adult male and female hosts. The development of ductus deferens and seminal vesicle from female UGR's grafted into male hosts and uterus from male UGR's grafted into female hosts demonstrates that the mesenchyme of embryonic UGR's is capable of participating in the development of either male or female urogenital structures. During normal development of the female urogenital tract, the bisexual morphogenetic potentiality of UGR mesenchyme persists postnatally as demonstrated by the ability of uterine stroma to support normal differentiation of epithelium of ductus deferens in male hosts. Conversely, during the normal development of the male urogenital tract, the morphogenetic potentiality of mesenchyme of the urogenital ridge is restricted as stroma from the ductus deferens appears incapable of participating in uterine morphogenesis in male or female hosts. These differences in the developmental properties of UGR stroma may be attributed to differences in hormonal conditions in male and female fetuses.
An ultrastructural analysis of chick embryonic skin development in vitro
Authors: Carinci P. , Simonelli L. , Bubola G. , Pettazzoni P. 
Published: June 2005

AbstractBehaviour of 6‐day chick embryo thigh skin in vitro in two different nutrients was studied electron microscopically.In explants supported with chicken serum containing medium epithelium keratinized faster than and in a similar way to that in ovo, except for the absence of corpuscola cribriformia in pericytes. It did not in explants supported with chick embryo extract containing medium, but underwent a noticeable ultrastructural evolution, mainly of granular reticulum and Golgi complexes.In the two series of culturs mesenchyme presented the same ultrastructural characteristics, especially as far as collagen fibers were concerned.The above data rule out the suggested regulatory role of collagen fibers in epidermal differentiation and support a possible epidermal two‐step differentiative process. They are discussed in relation to the general mechanisms implicated in skin evolution.
Adaptation of muscle pyruvate kinases to environmental temperatures and pressures
Authors: Low Philip S. , Somero George N. 
Published: June 2005

AbstractKinetic and structural properties of muscle pyruvate kinases from species adapted to different temperatures and hydrostatic pressures were examined. Most muscle pyruvate kinases can exist in two temperature‐dependent conformational states. For the low temperature conformers, activation free energies and enthalpies were proportional to the species' adaptation temperatures. The interspecific differences in activation parameters may be due to different amounts of weak bond formation/rupture during the rate‐limiting event(s) in catalysis. When comparisons of substrate binding ability at physiological temperature, is are made, a marked conservation in apparent Km values is observed among species. Structural rigidity, as estimated by heat inactivation temperature, is positively correlated with adaptation temperature. The apparent size of the conformational change which occurs during catalysis is also positively correlated with cell temperature, except for enzymes for deep‐sea species.
On the diversity of sperm histones in the vertebrates: II. A cytochemical study of the basic protein transitions during spermiogenesis in the cartilaginous fish Hydrolagus colliei
Authors: Bols N. C. , Kasinsky H. E. 
Published: June 2005

AbstractSpermiogenesis in the ratfish (Hydrolagus colliei) is characterized by unusual changes in the basic proteins of the nucleus. Cytochemical analysis indicates that early spermatids in this cartilaginous fish contain the somatic type of histones. However, late spermatids contain the salmon type of sperm histone whereas spermatozoa display the mouse/grasshopper type designated by Bloch ('69). Such an unusual cytochemical shift from protamine in the spermatid to “stable protamine” in the sperm has not been documented heretofore.
The nature and development of sex attractant specificity in cockroaches of the genus Periplaneta. II. Juvenile hormone regulates sexual dimorphism in the distribution of antennal olfactory receptors
Authors: Schafer Rollie , Sanchez Thomas V. 
Published: June 2005

AbstractSexual dimorphism of antennal sense organs appears only at the adult stage during normal development of the cockroach, Periplaneta americana. Adult males acquire approximately twice as many olfactory sensilla as females at the terminal ecdysis. When terminal instar larvae are subjected to unilateral antennectomy, most ecdyse to supernumerary larvae rather than adults. Sexual dimorphism is not evident in the intact (unamputated) antenna during the extra larval stage, but appears at the following ecdysis which leads to the adult stage. Allatectomy of male and female larvae in the penultimate instar produces adultoids which show antennal sexual dimorphism. Whole‐body treatment of terminal instar larvae with exogenous juvenile hormone‐mimic (JH‐M) results in supernmerary larvae which lack antennal sexual dimorphism. When these superlarvae are removed from the influence of JH‐M, they ecdyse to adults with antennal sexual dimorphism. Topical application of JH‐M to male antennae early in the terminal larval instar results in the emergence of adults which lack the total male complement of antennal sensilla, but are otherwise normal‐appearing. These results indicate that an inhibitory action of juvenile hormone prevents the appearance of antennal sexual dimorphism during normal larval development.
Daily variations in the effects of disturbance on growth, fattening, and metamorphosis in the bullfrog (Rana catesbeiana) tadpole
Authors: Horseman Nelson D. , Meier Albert H. , Culley Dudley D. 
Published: June 2005

AbstractBullfrog tadpoles subjected to the daily disturbance of water replacement demonstrated differences in the rates of growth and metamorphosis and in fatbody weights which depended on the time of day when water replacement occurred. Early daily disturbances stimulated larval growth whereas midday disturbances stimulated metamorphosis. The time when the daily disturbances caused fattening changed during metamorphosis so that younger tadpoles fattened when disturbed early in the photoperiod and older tadpoles when disturbed at midday.
A contribution to the problem of the origin of the blastema cells in planarians: A karyological and ultrastructural investigation
Authors: Gremigni Vittorio , Puccinelli Ileana 
Published: June 2005

AbstractThe basic problem in Planarian regeneration, i.e., the origin of blastema cells, has been tackled by means of a karyological investigation carried out on a triplo‐hexaploid biotype of Dugesia lugubris. The main characteristic of this biotype is that male germ cells are karyologically distinguishable from female germ cells and from the somatic cells.Sexually mature specimens were transected at a caudal level, posterior to the testes: from each transected specimen two regenerants were obtained, both of which formed a blastema. Thirty‐six hours after the transection most of the metaphase cells of the anterior regenerant blastema (a.r.b.) had 12 chromosomes. However, cells with 8 chromosomes as well as cells showing signs of chromosome elimination were also present. Three days after the transection only cells with 8 or 12 chromosomes could be detected in the a.r.b.The ultrastructural examination of the 36‐hours‐old a.r.b. revealed that some blastema cells display features which can be interpreted as indicating a process of dedifferentiation, the others being virtually undifferentiated. In the posterior regenerant blastema (p.r.b.) of sexually mature specimens only cells with 12 chromosomes were present. The same applies to both the a.r.b. and p.r.b. of sexually immature specimens and to developing embryos.These findings suggest that in the sexually mature planarians studied, the blastema is formed mainly by triploid cells. However, in those regenerants which still possess testes, immature male germ cells can also contribute to the blastema formation. The possible role played by these male germ cells in the reconstitution of the missing tissues in the biotype studied is also discussed.
Changes in the cell coat at the onset of gastrulation in Xenopus laevis embryos
Authors: Johnson Kurt E. 
Published: June 2005

AbstractFour developmental stages of Xenopus laevis embryos were fixed in standard electron microscopic fixatives with 1% lanthanum nitrate added. This treatment reveals a lanthanum staining material (LSM) on the cell surface and in extracellular spaces. Morula and blastula stage cells have a small amount of LSM; in blastulae, 3±3 SD % of the cell surface is coated with LSM. In early gastrulae, 29±6 SD % of the cell periphery is covered with LSM. In late gastrulae, 82±13 SD % of the cell periphery is either coated with LSM or faces a space with LSM in it. There is also an appreciable accumulation of LSM within extracellular spaces during gastrulation.
Alterations in lipid composition of liver cell plasma membranes during development
Authors: Eberspacher Bruno E. , Organisciak Daniel T. , Massaro Edward J. 
Published: June 2005

AbstractLiver plasma membranes of Swiss‐Webster CFW mice ranging in age from 5 to 165 days were isolated employing a two‐phase dextran/polyethylene glycol polymer system. Electron microscopy revealed low mitochondrial and microsomal contamination. Lipids were quantitatively extracted and subjected to two dimensional thin layer chromatography. Individual lipids were eluted and phosphorus was measured by the Malachite green method. Cholesterol was quantitated by the micro Lieberman‐Burchard method and sphingolipids were quantitated fluorometrically with fluorescamine.During development, phosphatidylethanolamine levels decreased from 43.2% to 19.5% whereas phosphatidylcholine levels rose from 26.6% to 45.2%. The ratio of phospholipid/cholesterol remained essentially constant during development; but the sphingolipid/cholesterol and sphingolipid/phospholipid ratios increased from 0.75 to 1.79 and 0.11 to 0.34, respectively.
The phlorizin effect on the transport of sugars at the antiluminal face of teased flounder tubules
Authors: Kleinzeller Arnost , Dubyak George , Mullin James F. , McAvoy Elizabeth M. 
Published: June 2005

AbstractThe effect of phlorizin on the uptake of sugars by teased renal tubules of the flounder (Pseudopleuronectes americanus) and slices of rabbit kidney cortex was investigated:
Increasing concentrations (0.05–0.5 mM) of phlorizin inhibited the uptake of D‐glucose at the antiluminal face of the tubular cells by affecting primarily the cellular levels of glucose phosphates, whereas the levels of free glucose remained constant. This result suggests the possibility that the actual transport step is associated with sugar phosphorylation.
As opposed to the high affinity of phlorizin for the Na+‐dependent active transport system for methyl‐α‐D‐glucoside in flounder and rabbit kidney, the carrier shared by glucose, 2‐deoxyglucose and mannose at the antiluminal face of tubular cells displays a low affinity for the inhibitor.
It is suggested that glucose and its C2‐analogs enter the renal tubular cells at the antiluminal face by a phosphorylating pathway which has a low affinity for phlorizin, and mix readily with the metabolic pool. This transport pathway serves the nutritional requirements of the cells.
Regeneration of the retina in the adult newt,Triturus cristatus, following surgical division of the eye by a post‐limbal incision
Authors: Levine Robert 
Published: June 2005

AbstractAn autoradiographic and histological study of retinal regeneration following a post‐limbal ocular incision, inTriturus cristatus, is described. In these cases there is a major contribution to the regenerating retina from both the anterior complex (pars ciliaris retinae: ora serrata) and the retinal pigment epithelium. The tissue derived from the anterior complex can independently differentiate into retinal tissue if the anterior and posterior parts of the regenerate do not join. This contrasts with the situation following a limbal incision to the eye where the regenerative response of the anterior complex is inhibited.The significance of labelling patterns in the regenerating retina, following administration of3H‐thymidine, is discussed.
Inhibition of epidermal cell migration by concanavalin A in skin wounds of the adult newt
Authors: Donaldson Donald J. , Mason James M. 
Published: June 2005

AbstractPigment cell migration was used as an indicator to study the effects of the plant lectin, concanavalin A (con A), on epidermal cell closure of skin wounds. Continuous immersion of wounded animals in 10–100 μg/ml of con A greatly slowed but did not stop epidermal cell migration. Thus, untreated animals closed wounds in 12 to 24 hours while some treated wounds were still open after three days. Removal from con A after 24 hours, allowed inhibited wounds to close faster than those left in con A. Brief (30‐minute) immersion of wounded animals in con A, either before or after migration had begun, suppressed closure for four to eight hours, demonstrating that the affinity for con A persists as epidermal cells migrate. When the left forelimb of bilaterally wounded animals was immersed in con A, it caused suppression of migration only on the immersed side, indicating a local rather than systemic site of action. Mixture with its competing sugar, alpha methyl D mannoside, abolished the effects of con A. The mechanism by which this lectin suppresses epidermal cell migration is unknown but clearly involves binding of the molecule to glycoprotein or glycolipid receptors on the cell surface.
Chronology of tooth development in the rainbow trout (Salmo gairdneri)
Authors: Berkovitz B. K. B. 
Published: June 2005

AbstractA histological study was undertaken on the jaws of three rainbow trout (Salmo gairdneri) for which the previous dental record of each tooth position had been obtained by taking wax impressions of the jaws twice weekly. This has provided accurate data concerning the time sequence of events in the life cycle of the teeth. The periods of development leading to initial calcification, resorption and exfoliation of its predecessor, and ankylosis were rapid and each was calculated as taking no more than one week out of a life cycle, in the case of a mandibular tooth of a fish of body length 15 cm, of approximately 16 weeks. There was some evidence that resorption of a functioning tooth could commence internally as well as externally. Eruptive movements have to be accomplished rapidly and some contribution appears to be made by an uprighting of the tooth from its angled, developmental position.
Physiological adjustments to dilution of the external medium in the lip‐shark, Hemiscyllium plagiosum (bennett). III. Oxygen consumption and metabolic rates
Authors: Chan D. K. O. , Wong T. M. 
Published: June 2005

AbstractDuring the initial period of adjustment of the lip‐shark, Hemiscyllium plagiosum, to a dilute medium there is an apparent decline in rate of oxygen consumption which is due mainly to the accumulation of water in the body. There is a rapid loss of lipid and glycogen from the liver.After complete adaptation to the dilute medium, the oxygen consumption rate increases to the original level of the animal in sea water. A metabolic balance sheet based on the oxygen consumption, total nitrogen excretion and the assumption that muscle catabolism supplies the bulk of the energy, indicates that the lip‐shark has an elevated catabolic rate in the dilute medium. The calculated catabolic rate agrees well with the rate of loss in body weight in the unfed fish.Blood glucose is well maintained while tissue‐lactate concentrations decline following adaptation to 46% sea water. Thus the availability of oxygen and metabolite are not limiting with respect to survival in diluted sea water.
Abnormal morphogenesis of feather structures and pattern in the chick embryo integument. II. Histological description
Authors: Brotman Harris F. 
Published: June 2005

AbstractThe development of skin and feathers in highly feathered scaleless mutants and normal Single Comb White Leghorn chick embryos was analyzed histologically. In addition, the growth of mutant feathers in chorioallantoic membrane culture is reported as a verification of several inferences made from observations of serially staged fixed specimens.The most striking feature of scaleless high line feather development is the widespread appearance of condensed or nearly condensed dermis. The discrete arrangement of normal placodes with underlying condensed dermis is replaced in the mutant by a heterogeneously shaped group of extremely large islands of columnar (“placodized”) epithelium as long as 3,000 μ. The shape and extent of the condensed areas of dermis reflect the shape and extent of the overlying “placodized” epithelium. The polarity of the epidermis in normal feather germs, i.e., thicker epidermis on the posterior surface, is absent in mutant feather germs. This absence of epidermal polarity is reflected in the aberrant outgrowth of the mutant feather primordia.In the mutant, the basal cell layer of the epidermis invades the dermal core of the aberrant feather germs and may form barb vane ridges or feather sheaths. This process has no counterpart in the development of normal down feathers.
Epidermal‐dermal tissue interactions between mutant foot skin and normal back skin: A comparison of the inductive capacities of scaleless low line and normal anterior foot dermis
Authors: Brotman Harris F. 
Published: June 2005

AbstractThe inductive capacities of 9‐ to 16‐day anterior foot dermis of scaleless low line and normal embryos were compared by recombining them with a common source of epidermis, i.e., 7‐day normal back epidermis. Tissue recombinants were cultured as grafts to the chorioallantoic membrane (CAM). Both normal and scaleless low line dermis of 12 to 13 days of incubation began to lose their ability to elicit feather production in 7‐day normal back epidermis. Normal foot dermis began to elicit scale production at 12 to 13 days, whereas scaleless low line anterior foot dermis maintained feather production at a low level.It is inferred that without being associated with scale placode formation, scaleless low line anterior foot dermis does not acquire specific inductive capacities related to the production of an outer scale surface in the overlying epidermis. Feather placodes do not function as surrogates of scale placodes. The difference between normal and scaleless low line anterior foot dermis in terms of specific inductive capacities related to scale production is interpreted as a secondary effect of the action of the scaleless allele in interfering with scale placode formation in the scaleless low line anterior foot epidermis.
Low salt and high PH in the blood of amazon fishes
Authors: Mangum C. P. , Haswell M. S. , Johansen K. 
Published: June 2005

AbstractAll but one of 15 species of fishes and two crustaceans from the Amazon River system have reduced levels of inorganic ion activity in the blood, which results from the purity of Amazon waters. In many of the teleosts, low ion activity is accompained by high blood pH, due to the presence of high levels of HCO and ammonia. The activities of H+ and Cl− have the important respiratory consequence of raising the oxygen affinity of the hemoglobins in water‐breathing species in this chronically hypoxic environment.
Control of metamorphic events in a neotenous urodele Ambystoma mexicanum
Authors: Tompkins Robert , Townsend Janis K. 
Published: June 2005

AbstractExternal metamorphosis in the normally neotenous urodele, Ambystoma mexicanum, can be induced by continuous immersion in thyroxine solutions of 5 × 10−8 M or more. The natural larval‐to‐adult hemoglobin change occurs in untreated animals at 100–150 days of age, unaccompanied by external metamorphosis. The hemoglobin change is inducible prematurely by continuous immersion of larvae in a thyroxine solution of at least 3 × 10−8 M‐a concentration insufficient to induce external metamorphosis.
Morphology of mouse egg cylinder development in vitro: A light and electron microscopic study
Authors: Wiley Lynn M. , Pedersen Roger A. 
Published: June 2005

AbstractPhase contrast, light, and electron microscopy showed that mouse egg cylinder development from the blastocyst stage in vitro closely resembled the egg cylinder stages of the fourth to seventh days of gestation in vivo. Primary endoderm and ectoderm formed on day 2 of culture, and on day 3 visceral and parietal endoderm could be distinguinshed. Mesoderm formed on days 6.5‐7 by delaminating from a thickened region of embryonic ectoderm. Extraembryonic ectoderm developed as single layer of cuboidal epithelial cells that appeared to originate from polar trophoblast cells. By day 8 of culture egg cylinders had an ectoplacental cavity, an exocoelom, a proamnionic cavity, a chorion, and an allantois and resembled egg cylinders in vivo after seven days' gestation. However, cultured blastocysts took longer to develop to these egg cylinder stages than embryos in vivo (8 days in vitro vs. 4 days in vivo) and were shorter (600 μm in vitro vs. 700 μm in vivo). The development of mural trophoblast, parietal endoderm, Reichert's membrane, and ectoplacental cone also differed from that of their counterparts in vivo. Nevertheless, because the egg cylinder itself, which produces the embryo proper, develops similarly in vitro as in vivo, we suggest that cultured mouse blastocysts provide an excellent model for studies on early postimplantation embryogenesis.
Bioelectricity and regeneration. I. Initiation of frog limb regeneration by minute currents
Authors: Borgens R. B. , Vanable J. W. , Jaffe L. F. 
Published: June 2005

AbstractWe have applied 0.2 μamps of current to the forelimb stump of Rana adults for several weeks. The stimulator was designed to avoid introduction of any physiologically active electrode products into the tissue. Current was applied to the dorsal postaxial region of the stump. Cathodal (i.e., distally negative) current initiated partial regeneration; anodal (i.e., distally positive) current initiated extensive destruction of the limb; while implantation of sham stimulators (delivering no current) yielded limbs showing just a healing response. Regeneration was indicated by organized extension of the severed radio‐ulna, newly formed muscle, ligament, and isolated cartilage rods that were partially segmented. Moreover, extraordinarily large amounts of nerve developed in the regenerated tissue. We conclude that the cathodally initiated regeneration was mediated by small electrical fields within the stump and not by electrode products. However, an electrode product (Ag+ ion) cannot be completely excluded as a possible mediator of anodal destruction.