bluuebunny/crossref_metadata_2025_split huggingface dataset:
The growth of newborn rat tibiae in a continuousflow organ culture system
Authors: Schwartz P. L. , Wettenhall R. E. H. , Bornstein J. 
Published: June 2005

AbstractA technique for continuous‐flow organ culture of newborn rat tibiae in a chemically defined medium is described. The growth characteristics of such bones during three days of culture, in terms of length, weight, hydroxyproline content, galactosamine content, and calcium content, are compared with corresponding growth in vivo and are seen to be reduced, especially beyond the first day of culture. Net synthesis of hydroxyproline and galactosamine during culture is demonstrated.It is shown that cultured bones are capable of incorporating labelled proline into hydroxyproline and labelled sulphate into bound form linearly for 72 hours, indicating continuing matrix synthesis in vitro.The implications of these findings are discussed.
Evolution of a nervous system specific lactate dehydrogenase isozyme in fish
Authors: Horowitz Jordan J. , Whitt Gregory S. 
Published: June 2005

AbstractL‐lactate dehydrogenase (LDH) exists as tetrameric isozymes in all vertebrates. The polypeptide subunits are encoded in at least two genetic loci, A and B. A third LDH locus, the E locus, is present only in fish. The distinctive E4 isozyme encoded by this locus is synthesized in the cells of the teleost nervous tissue, particularly in the photoreceptor cells.Electrophoretic and immunochemical procedures were employed to determine which orders of fish have representatives which contain this nervous system specific LDH isozyme. In addition to the 50 species of teleostean and non‐teleostean fish examined, a compilation was made of other species reported to contain this enzyme.The LDH E gene function was not detected in Agnathans, Chondrichthyes, Dipnoans, Chondrosteans, and Holosteans. The LDH E gene appears to be restricted to the teleosts. However, some orders of teleosts, e.g., the Cypriniformes, contain many families which lack the E4 isozyme. The LDH E gene appears to have arisen from a duplication of the LDH B gene near the time of the adaptive radiation of the teleosts.The immunochemical analyses of the LDH isozymes from these fish indicate that the LDH A and B loci of non‐teleostean fish have not diverged to the extent as these same loci in teleosts.
Reticuloendothelial system activity and antibody formation in hibernating hedgehogs (Erinaceus europaeus)
Authors: Franceschi Claudio , Forconi Giulio , Perocco Paolo , Di Marco Antonino Tano , Prodi Giorgio 
Published: June 2005

AbstractThe reticuloendothelial system (RES) activity by the method of colloidal carbon clearance and the antibody production against heterologous erythrocytes by the method of hemagglutination were studied in hibernating hedgehogs.The organs involved in RES activity and antibody production were histologically studied.The data obtained show that the RES activity in the liver is unaffected in hibernating animals while uptake and localization of carbon particles by the spleen is impaired. The suggested hypothesis is that of a defect in the phagocytic activity of the spleen's macrophages, even if the effects of the disturbance in the handling of hibernating animals is to be considered.The antibody production is inhibited or, at least, reaches no significant values in hibernating hedgehogs.All these facts may be correlated with a general and marked involution of all the lymphoid organs. In fact we can observe a reduced white pulp and involuted follicles in the spleen, a smaller size of the thymus and its substitution by brown fat tissue, and smaller lymphnodes containing brownish material. The results are discussed in relation to the scanty and contradictory data available in the literature.
Differences in the morphogenetic properties of mouse and chick embryonic liver cells
Authors: Burdick Morton L 
Published: June 2005

AbstractAggregates containing trypsin‐disaggregated mouse and chick embryonic liver cells were prepared, and in confirmation of Moscona's reports, no substantial sorting out was seen. While this behavior could mean that the morphogenetic properties of these cells are the same, alternative explanations have not been ruled out. Thus, additional comparisons of these cells were needed to decide whether these properties are the same, and two such tests were performed.It is known that when two pieces of chick embryonic liver are fused together, neither piece envelops the other. If mouse and chick embryonic liver cells had identical properties, no envelopment would be expected in mouse‐chick liver fusions. Such fusions were prepared, and contrary to this expectation, chick liver enveloped mouse liver almost invariably.It is known that chick embryonic liver cells sort out from chick embryonic heart ventricle cells in mixed aggregates. If mouse liver cells had properties identical to those of chick liver cells, it would be expected that they too would sort out from chick ventricle cells. Mouse liver‐chick ventricle cell aggregates were prepared, and contrary to this expectation, no substantial sorting out was found.These two tests demonstrate that the morphogenetic properties of mouse and chick embryonic liver cells are not the same. Clearly, a new explanation must be found for their lack of sorting out, and several possible explanations are discussed.
An electrophoretic and biochemical analysis of acid phosphatase in the tail of Xenopus laevis during development and metamorphosis
Authors: Robinson Helen 
Published: June 2005

AbstractThe properties of acid phosphatase from tail tissues of Xenopus laevis tadpoles have been investigated by means of acrylamide gel electrophoresis and biochemical assay with alpha‐naphthyl acid phosphate as substrate. Studies were made on intact tails during development and spontaneous metamorphosis, and on isolated tail tips undergoing thyroxine‐induced regression in culture.Quantitative and qualitative changes in acid phosphatase are found to occur during the process of tail resorption. The same types of changes are found during both spontaneous metamorphosis and thyroxine‐induced regression in culture, although the magnitude of these changes is greater during spontaneous metamorphosis. Tail resorption is characterized by increases in total activity (per tail) and specific activity (per unit of protein) of acid phosphatase, as well as changes in the pH optimum and heat sensitivity of the enzyme. Electrophoresis of enzyme preparations from whole tails and different parts of the tail resolves two distinct forms of the enzyme which are both present throughout growth and regression. Densitometric tracings of these gels reveal that the ratio of one form to the other remains constant during growth and the early stages of tail regression. However during late stages of tail regression this ratio becomes significantly altered, due primarily to an increase in one form. Biochemical analysis of enzyme preparations subjected to hypotonic conditions and to Triton X‐100 indicates that there is an increase in the proportion of soluble versus bound enzyme in tail tissues undergoing advanced atrophy. Possible implications of these results are discussed.
Assay of prolactin in vertebrate pituitaries by its dispersion of xanthophore pigment in the teleost Gillichthys mirabilis
Authors: Sage Martin , Bern Howard A. 
Published: June 2005

AbstractA simple, rapid assay for prolactin is described using the pigment‐dispersing response of the xanthophores in the teleost Gillichthys mirabilis. The assay is highly specific for prolactin in lower vertebrates, but mammalian growth hormone (STH) also produces a response in the assay. The assay is sensitive, detecting 10−11 gm (dry weight) of a teleostean pituitary rostral lobe. Taxonomic specificity is high: 5 μg ovine prolactin is required for a similar effect. Activity in the agnathan pituitary was negligible. In elasmobranchs, teleosts and reptiles, activity was localized in the rostral pituitary region. Lung‐fish pituitary activity was low, resembling that in tetrapods. Comparison of pituitary xanthophore activity from the several vertebrate classes indicates an inverse relationship with pigeon cropsac activity, previously published, suggesting that the evolution of a single active site on the prolactin molecule could account for both activities.
A histological study of the early stages of cutaneous wound healing in lizards in in vivo and in vitro
Authors: Maderson P. F. A. , Roth S. I. 
Published: June 2005

AbstractThe responses of the skin to wounding from six hours to ten days have been studied histologically in a variety of lizard species. Whatever the size of the initial wound, all aspects of cutaneous structure, i.e., general scale architecture, epidermal cell activity, and epidermal specializations, are disrupted by a sequence of cellular events quite distinct from those described in other vertebrates. The epidermis on either side of the incision dies along a variable length, and epithelial migration occurs along a prepared hypercellular path through the dermis where the normal collagen fibers are destroyed. A segment of apparently physically undamaged tissue is discarded from the body surface and the subjacent “wound epidermis” undergoes rapid cell proliferation and maturation leading to the formation of a hyperplastic cornified tissue whose cells resemble the normal α‐layer, but which shows no indication of the typical epidermal generation structure.
Morphological changes in the “prolactin” cell of the freshwater teleost, Xiphophorus hellerii, in salt water
Authors: Holtzman Seymour , Schreibman Martin P. 
Published: June 2005

AbstractThe swordtail, Xiphophorus hellerii, requires prolactin for survival in its natural freshwater habitat. Progressive cytological and ultrastructural changes of prolactin cells were observed in sibling females after a transfer from fresh water to one‐third sea water for periods ranging from 18 hours to 30 days. At the light microscope level, cells became progressively smaller, displayed a decrease in acidophilia, and lost their nucleolar prominence. Electron microscopy confirmed these observations. There was a reduction of perinuclear rough endoplasmic reticulum and a progressive decrease in the size distribution of secretory granules from an average of 2800 Å diameter in freshwater fish to 1700 Å for animals in dilute sea water for 30 days. Furthermore, a class of granules over 3000 Å, representing approximately 45% of the granules in prolactin cells of freshwater animals, were not present after 18 hours in dilute sea water. These observations presumably reflect a diminished requirement for prolactin in a saline environment. Possible alternative explanations for the mechanisms of these changes are discussed.
Effects of temperature on shortening of isolated Rana pipiens tadpole tail tips
Authors: Fry Anne E. 
Published: June 2005

AbstractTo determine how temperature influences the rate of amphibian metamorphosis when acting directly on peripheral tissues, Rana pipiens tail tips from larval stages II–IV were cultured in the presence of 1 × 10−6 M or 1 × 10−7 M DL‐thyroxine at four different temperatures: 5°C, 10°C, 20°C, and 26°C. Five experiments were performed with variations in temperature, length of exposure to, and concentration of, hormone.Results indicate a positive correlation between temperature and rate of tail shortening in vitro, thus demonstrating that temperature can influence metamorphosis by acting on the periphery directly in addition to its effect on the hypothalamus‐pituitary‐thyroid axis. Low temperatures retard or inhibit shortening of isolated tails both by decreasing thyroxine uptake and by influencing its action after it is within the tail. Length of exposure to hormone and concentration also affect the rate of resorption.
Formation and differentiation of the upper pinacoderm in reaggregation masses of the sponge Microciona prolifera (Ellis and Solander)
Authors: Bagby Roland M. 
Published: June 2005

AbstractThe ultrastructures of gray cells and archeocytes were studied in adult Microciona prolifera to aid in their identification in reaggregation masses. Gray cells were easily identified by their uniform, densely‐stained granules and abundant glycogen particles. A small, dense nucleolus was occasionally observed. Archeocytes lacked the characteristic granules of the gray cell, and a large nucleolus with a less dense core was invariably found.To follow the stepwise formation and differentiation of the upper pinacoderm, pieces of sponge were squeezed through cloth into polyethylene dishes, and the resultant masses were fixed with 2% OsO4 in 90% sea water at 6, 12, 24, 48, and 96 hours after dissociation. Fixation, dehydration and embedding in the same dish preserved the orientation of the masses.Reaggregation masses of less than 150 μ diameter failed to differentiate a pinacoderm while in masses greater than 250 μ virtually the entire upper surface was composed of exopinacocytes by 96 hours. The gray cells and archeocytes were little changed from their structure in the intact sponge except for a more rounded shape and a greater number of phagosomes in the archeocytes. Cells forming the surface epithelium contained large nucleoli, phagosomes and other characteristics similar to those of archeocytes, while cell types intermediate between gray cells and exopinacocytes, were not observed. It was concluded that gray cells do not form exopinacocytes, and archeocytes form the nucleolated exopinacocytes.
Middle‐ear function in a monotreme: The echidna (Tachyglossus aculeatus)
Authors: Aitkin Lindsay M. , Johnstone Brian M. 
Published: June 2005

AbstractThe mechanics of the middle ear bones of echidna (Tachyglossus aculeatus) were studied using the Mössbauer technique. A small radioactive source was placed on the stapes and the alterations in the frequency of the emitted γ‐ray, which occurred when the stapes vibrated during sound stimulation, were detected by a proportional counting system and absorber. In this way the velocity of stapes motion could be measured in response to different acoustic frequencies and intensities.The ossicular system of echidna consists of a large malleus with an anteromedially directed process, the processus gracilus; an incus which is ankylosed to the malleus, and a columelliform stapes. The tympanic bone supports the eardrum and appears firmly locked to the processus gracilus. The malleus and incus are tightly attached, at their lateralmost corner, to the periotic bone. This latter attachment causes the middle ear chain to be very stiff.The velocity of stapes motion at 100 dB SPL is very low (0.0014 mm/sec) at 100 Hz and rises to a peak at 6 kHz (0.1 mm/sec). Velocity decreases at approximately 12 dB/octave as frequency is increased beyond 6 kHz. Amplitude of stapes motion is relatively constant at about 0.002–0.004 μ for 100 dB SPL between 100 Hz and 6 kHz and drops off at 18 dB/octave at higher frequencies.Comparison of these results with those for some lizards and placental mammals reveals that the echinda middle ear bones are considerably less efficient in transmitting airborne vibrations than those of the other animals.
Strobilation in the Chesapeake Bay sea nettle Chrysaora quinquecirrha. I. The effects of environmental temperature changes on strobilation and growth
Authors: Loeb Marcia J. 
Published: June 2005

AbstractObservation of Chrysaora polyps taken from the Chesapeake Bay and maintained in the laboratory reveals at least four morphological types of animals, chiefly distinguished by the number of tentacles they bear and the manner of strobilation. All of the types strobilate when warmed after sufficient chilling; several waves of strobilations may result from the initial stimulus. One of the types of Chrysaora polyps was selected for characterization with respect to environmental control of its strobilation behavior. These animals must be chilled for a minimum of seven weeks at 20°C before they are able to respond to warming to 26°C by strobilating; it is proposed that a number of factors accumulate during chilling which enable polyps to strobilate when warmed. The time course of strobilation, including release of ephyrae, appears to be determined by the temperature at which strobilation is initiated.The growth of Chrysaora polyps seems to be regulated by both the exact temperature of the environment and relative changes in environmental temperature.
A functional taxonomy of epidermal appendages in mice based on the distribution of nerve endings
Authors: Straile William E. , Mann Stanley J. , Cole Carl E. 
Published: June 2005

AbstractExisting data on integumental nerve endings provide a basis for classification of the visible epidermal appendages (hairs and dermatoglyphic pads) in mice. Hairs that have long tips (tylotrichs and bristles) are surrounded by large encapsulated cylinders of coarse nerve fibers. Half of these hairs (tylotrichs) are associated with disk‐shaped dermatoglyphic pads, which contain innervated Merkel cells. Hairs that have short tips are surrounded by small cylinders of fine nerve fibers, but contiguous dermatoglyphic pads and dermal capsules are missing. Constrictions in the shafts of short‐tipped hairs vary unpredictably and are not readily correlated with nerve endings.Analysis of the distribution, structure and physiology of nerve endings and dermatoglyphic pads makes possible (1) the recognition of meaningful features of hair structure (e.g., contour of the tip) that are involved in the transmission of mechanical energy to tactile receptors, and (2) the disregard of equivocal features of hair structure (e.g., 1 constriction in the shaft), which vary between the sexes, among body regions and among inbred strains.
The appearance and distribution of vaginal antigen during the differentiation of the cervicovaginal epithelium in normal and estradiol‐treated mice
Authors: Forsberg John‐Gunnar , Kvinnsland Stener 
Published: June 2005

AbstractRabbits were immunized with vaginal epithelium from ovariectomized and estradiol‐injected adult mice. A crude IgG solution was prepared from the immune serum and was used for immunofluorescence studies (indirect method) of the appearance of antigen(s) specific for the vaginal epithelium during the differentiation of the cervicovaginal epithelium in neonatal mice. In neonatal untreated mice, the appearance of the antigen could be correlated with the mitotic activity and morphological transformation of the vaginal epithelium.Estradiol injected into neonatal mice had a two‐fold effect: it caused a precocious appearance of visible specific antigen in the untransformed pseudostratified cervicovaginal epithelium; however, in some mice it prevented the appearance of any visible antigen in the cervical epithelium, possibly by way of its inhibiting effect on cell divisions in this region. It is suggested that the epithelial cells must pass a “crucial mitosis” before being able to synthesize the antigen.The distribution of the antigen was also studied in immature and adult ovariectomized and estradiol injected mice. Estradiol strongly increased the small amount of antigen seen in the superficial cell layer of ovariectomized animals.
Is abnormal limb bud morphology in the mutant Talpid2 chick embryo a result of altered intercellular adhesion? Studies employing cell sorting and fragment fusion
Authors: Niederman Richard , Armstrong Peter B. 
Published: June 2005

AbstractIn the past, studies of avian limb morphogenesis emphasized epithelial‐mesenchymal tissue interactions and problems of determination of limb symmetry. In contrast, a recent hypothesis, based on studies of the aggregation rates of dissociated cells and on computer modeling, proposes that the paddle shaped polydactylous limb of the talpid3 mutant is the result of increased intercellular adhesion of limb bud mesoderm cells during limb development. The notion that differences in intercellular adhesion may have profound effects on limb morphogenesis has not been critically explored previously.The present experimental approach includes studies of cell sorting in aggregates containing both talpid2 and wild‐type cells. In this system, adhesive differences should result in cell sorting. Instead, cell sorting did not occur, indicating by this test at least, that limb bud mesoderm cells of talpid2 and wild‐type embryos are equally adhesive. This conclusion finds support from studies involving tissue spreading in fused fragments of talpid2 and wild‐type limb bud mesenchyme tissue and in studies of kinetics of aggregation of dissociated cells.
The behavior of the acetylcholinesterase cells of the anterior pituitary gland of artificially photostimulated female white‐crowned sparrows
Authors: Haase Eberhard , Farner Donald S. 
Published: June 2005

AbstractIn Zonotrichia leucophrys gambelii complete testicular development is induced in captive males subjected to long daily photoperiods. In identically treated females ovarian development is only partial. This partial development of the ovary, and the subsequent premature regression thereof, correlate with changes in activity of the “acetylcholinesterase cells” of the pars distalis. This adds to the evidence that these cells are gonadotropes.
Inhibition of cleavage and hatching of sea urchin embryos by serotonin
Authors: Deeb Samir S. 
Published: June 2005

AbstractThe addition of low levels of serotonin (20–50 μg/ml) to the rearing medium of sea urchin embryos specifically inhibits the hatching process by blocking the synthesis of an active hatching enzyme. Other developmental processes seem to be unaffected. Embryos are sensitive to serotonin during the first three cleavage divisions only. The uptake of RNA and protein precursors, and the rate of RNA synthesis are unaffected by serotonin, whereas the rate of protein synthesis is elevated by approximately 45% during the 2‐cell to 16‐cell interval of development.The addition of higher levels of serotonin, 75 and 100 μg/ml, causes retardation and blockage of cleavage division respectively.
Defective histogenesis and morphogenesis in the anterior shank skin of the scaleless mutant
Authors: Sawyer Roger H. , Abbott Ursula K. 
Published: June 2005

AbstractTimed‐sequence studies of scaleless anterior shank skin have shown that both histogenesis and morphogenesis are abnormal. An epidermal placode does not form in the mutant and thus the subsequent morphogenetic movements of placode into scale ridge are blocked as well. The dermis of the anterior shank remains flat rather than forming overlapping ridges. Two histologically distinct epidermal surfaces (outer and inner) are formed on either side of a normal scale ridge. In scaleless only a single epidermal surface develops and this is unlike either surface of a normal scale. An isolated dermal ridge of 16‐day normal embryonic scale can induce eight‐day chorionic epithelium to form both the outer and inner epidermal surfaces. Scaleless dermis of the same age when recombined with eight‐day CE will induce an epidermis typical of the normal outer scale surface, but no inner epidermal surface is formed. Previous studies have shown that the genetic defect is expressed in the epidermis and that at earlier stages scaleless dermis can, when associated with a normal epithelium, participate in placode formation and histogenesis of both epidermal surfaces. It seems reasonable to conclude that placode formation is initiated by the epidermis which thereby establishes heterogeneity in the scale dermis; thereafter, the scale dermis directs the histogenesis of the two epidermal surfaces.