bluuebunny/crossref_metadata_2025_split huggingface dataset:
Factors influencing sperm penetration of rabbit eggs in vivo
Authors: Harper M. J. K. 
Published: June 2005

AbstractUnfertilized eggs recovered from donor rabbits at known times after injection of HCG were transferred to the oviducts of mated recipients (prevented from ovulating by having their ovaries covered with nail polish) at specific times after mating. When newly ovulated eggs (11.25–13.5 hours after HCG injection) were left in the oviducts of the recipients for 1, 1.5, 2, 2.5 and 3 hours, 15, 30, 44, 59 and 75% respectively were penetrated by spermatozoa. If the unfertilized eggs were allowed to age in the oviducts of the donor before transfer then fertilizability decreased: only 41 and 25% of eggs 15–15.5 hours and 17–17.5 hours old at time of transfer respectively were penetrated during 2.5 hours in the recipients' oviducts compared to 59% of 13–13.5 hour eggs. No beneficial effect from maturation in the donor of the unfertilized egg and its membranes was observed. When eggs with cumulus cells removed were transferred to recipients at 9–9.5 hours after mating, then a decrease in the percentage of eggs penetrated during 2.5 hours in the recipients' oviducts was found. Removal of both cumulus and corona cells had no greater effect than removal of cumulus alone. However, when eggs similarly treated were transferred to recipients at 14 hours after mating, neither removal of cumulus nor of cumulus and corona cells had any effect on the percentage of eggs penetrated during 2.5 hours. It is concluded that when conditions for fertilization are not optimal the cumulus is important for ensuring meeting of sperm and egg, but that when conditions are optimal then presence of these cellular layers is not important. Whether the products of ovulation play a role in the final stages of capacitation of sperm was tested by transferring eggs into the oviducts of rabbits unilaterally ovariectomized (more than 3 weeks previously) at 13.5–14.75 hours after mating. No difference in percentage of eggs penetrated was observed between oviducts on the ovariectomized and intact sides. The contact of the sperm with the products of ovulation in the one oviduct did not give them an advantage over the sperm in the other oviduct without such contact. It was found that although only 30% of newly ovulated eggs were penetrated in 1.5 hours following transfer to recipients at 9–9.5 hours after mating, 57 and 66% were penetrated during the same period if the transfers of similar eggs were delayed until 13.75–14.0 hours and 19.5–20.0 hours after mating of recipients respectively. It is suggested that these increases in percentages of eggs penetrated are a reflection of the presence of more sperm or of more fully capacitated sperm in the oviduct at these later times.
The synchronization of oral development without cell division in Tetrahymena pyriformis GL‐C
Authors: Frankel Joseph 
Published: June 2005

AbstractCells of T. pyriformis strain GL‐C synchronized in an amino‐acid‐free medium underwent synchronous oral replacement in place of cell division. This involved development of an oral primordium at the anterior end of the cell, with a concomitant rounding of the cell. The timing of this development was very similar to that of primordium development during synchronous division. In some experiments a second synchronous oral replacement was observed about 90 minutes after the first.Synchronization of oral replacement was similar to that of cell division. Prior to the heat shocks cells maintained in amino‐acid‐free medium were undergoing oral replacement asynchronously (with no concurrent macronuclear DNA synthesis). During the synchronizing treatment, development was initiated in the inter‐shock intervals but was arrested by the 34° heat shocks. As a result, cells became progressively accumulated in the earliest stage of oral replacement development. This accumulation did not take place if a single continuous heat treatment was given, or if cells were maintained in 2,4‐dinitrophenol, actinomycin D, or cycloheximide during the periodic heat shock treatment.The synchronous oral replacement which took place after the end of the synchronizing treatment (EST) could be blocked completely by actinomycin D, cycloheximide, and puromycin, and partially by p‐fluorophenylalanine. Exposure to cycloheximide (1 μg/ml) during stage 1 of stomatogenesis (10–30 minutes after EST) resulted in arrest of development, exposure during stages 3 and 4 (45 minutes) brought about primordium resorption, while exposure in stage 5 (60 minutes) permitted completion of development, with subsequent partial resorption. These responses were identical to those of synchronized dividing cells treated at comparable stages.
Congenital eye defects in the mouse. III. Lens opacity in NAW‐wa‐2+ − +/Sp
Authors: Pierro Louis J. , Spiggle Jean 
Published: June 2005

AbstractA pin‐point lens opacity can be detected at a frequency of 90% in weanling mice from inbred strain NAW‐wa‐2+ − +/Sp. Defective lenses show abnormal thickening of the anterior epithelium localized over a region of persistent contact between the primary lens fiber mass and the epithelium.A morphological study of lens development indicates that the mutant strain clearly differs from normal as early as the twelfth day of embryonic life. In a lens sector associated with the naso‐ventral quadrant of the optic cup, cells undergoing the elongation characteristic of primary lens fibers are separated from the normal boundary of the anterior epithelium by a peculiar group of cells. These cells can still be detected on the following day; they do not differentiate into primary fibers. They contribute to the anterior epithelium instead, and the zone of elongation is asymmetrically displaced from the equator. Secondary fibers formed in this sector before birth do not completely displace the primary fibers from contact with the anterior epithelium. If secondary fibers formed during the neonatal period do not accomplish separation, abnormal thickening of the anterior epithelium begins around the end of the second week of postnatal life. The epithelial thickening and capsule‐like material deposited within it apparently provide the structural basis for the opacity detected upon gross examination.
Responses of perfused isolated leg preparations of the cockroach, Gromphadorhina portentosa, to L‐Glutamate, GABA, picrotoxin, strychnine and chlorpromazine
Authors: Faeder Isabelle R. , O'Brien Richard D. 
Published: June 2005

AbstractA perfused leg preparation of Gromphadorhina portentosa (Orthoptera) was developed for use in pharmacological studies and bioassay procedures. Study of tibial flexion with increasing stimulation intensity at low frequency revealed five fast motor units. Chlorpromazine (2.5 × 10−4 M) progressively blocked these motor units. GABA generally failed to affect fast system responses, even at high concentration (2.5 × 10−4 M). A high concentration (2.5 × 10−4 M), picrotoxin produced effects consistent with the interpretation that motor axon excitability was affected. Strychnine (2.5 × 10−4 M) produced no effect on isolated leg preparations. L‐Gultamate (pH 7.2) produced contractures; the threshold for this response was 2.5 × 10−4 M. Contractures were produced after application to resting muscle, and were also observed in preparations receiving low frequency indirect stimulation. The response to glutamate under the latter condition closely resembled incomplete tetanus. L‐Glutamate (2.5 × 10−4 M) produced a reversible depression of kick force in locusts. These responses are compatible with the hypothesis that L‐glutamate is an excitatory neuromuscular transmitter in insects.
Digestion in Haliotis rufescens Swainson (Gastropoda: Prosobranchia)
Authors: McLean Norman 
Published: June 2005

AbstractDigestion was studied in the marine archaeogastropod Haliotis rufescens, with emphasis on identification of absorptive regions in the gut. Extracellular enzymes were found in the digestive fluid. Absorption in the digestive gland was demonstrated by autoradiography of tissue sections after feeding animals on 14C‐labeled algae. After absorption, food was retained apically in the absorptive cells of the digestive gland in an insoluble form. Possible mechanisms of uptake are discussed. It was shown chromatographically that small compounds derived from the food were present in both the crop fluid and blood early in digestion. Studies in vitro showed that the crop epithelium was permeable to small organic materials. Glucose and phenylalanine were found to have been taken up by the crop epithelium in considerable quantities; smaller amounts were passed through the epithelium, and would in life be transferred to the blood. The surface area of the food mass was seen to be increased in an intestinal sorting area at the beginning of the intestine. The intestinal epithelium was shown in vitro to be permeable to glucose. It is concluded that the large crop is an important region of absorption, and that digestion and absorption continue to occur as food passes along the intestine.
Bioelectric interactions between cultured fetal rodent spinal cord and skeletal muscle after innervation in vitro
Authors: Crain Stanley M. 
Published: June 2005

AbstractElectrophysiologic analyses of cultures of various combinations of spinal cord and skeletal muscle tissues demonstrate that characteristic neuromuscular transmission can develop and be maintained for months in vitro. The studies include: (1) cultures of mouse embryo spinal cord with attached myotomes, explanted prior to formation of neuromuscular junctions, and (2) in vitro‐coupled fetal rodent cord and muscle explants, in which one tissue is grown in isolation before presentation of the other explant (0.5–1 mm apart).After innervation occurs during the first few weeks in vitro, selective stimulation of spinal cord evokes widespread synchronized twitches in the muscle tissue. Simultaneous microelectrode recordings of cord and muscle responses to local cord stimuli show that muscle action potentials generally occur with latencies of several msec after onset of cord discharges. Rhythmic spontaneous bursts of muscle potentials (and contractions) occur, at times, in close correlation with periodic cord discharges.d‐Tubocurarine (1–10 μg/ml) selectively blocks neurally evoked muscle contractions while electric stimuli applied directly to the muscle fibers are still effective. Many apparently non‐innervated fibers, on the other hand, show sporadic, asynchronous fibrillations which are not altered by cord stimuli nor blocked by curare.Eserine and strychnine produce characteristic increases in repetitive muscle activities related to the primary site of action of these pharmacologic agents.Cultured neuromuscular tissues can, then, provide a valuable model system for correlative physiologic and cytologic studies of nerve and muscle cells during critical stages of maturation and formation of intercellular relationships under isolated conditions in vitro.
Does differential adhesion govern self‐assembly processes in histogenesis? Equilibrium configurations and the emergence of a hierarchy among populations of embryonic cells
Authors: Steinberg Malcolm S. 
Published: June 2005

AbstractThe differential adhesion hypothesis attributes sorting‐out behavior of embryonic cells to differences in the strengths of their intercellular adhesions. It suggests that cells in mixed populations rearrange themselves to minimize their total adhesive free energy. The final configuration adopted is viewed as approaching a moststable or equilibrium configuration, with the less cohesive cell/population tending to envelop the more cohesive one.The hypothesis enables two predictions to be made. First, if the final configuration adopted by a mixed cell population indeed approximates an equilibrium configuration, the same final configuration should be approached irrespective of the starting configuration. Second, comparison of the equilibrium configurations for all possible pair‐combinations of a series of cell populations of different types should reveal a hierarchy of “preference” for the internal position, reflecting a hierarchy of cellular cohesiveness.These predictions have been tested and confirmed. First, any particular pair of tissues approaches the same final configuration, irrepective of whether the cells are initially randomly intermixed or tissue fragments are laterally joined. Second, the predicted hierarchy of preference for the internal position has been found, consistent with a hierarchy of cellular cohesiveness.An effort has been made to clarify confusions that have arisen concerning the differential adhesion hypothesis. It is particularly stressed that the hypothesis offers an explanation for cell population behavior in terms of relative strengths of cell adhesions and makes no proposals concernnig the chemistry of adhesion. However, the value of equilibrium configurations in guiding biochemical investigations of cell surface adhesives is pointed out, as is the relevance of the present observations to natural morphogenetic events.
Fusion of unfertilized mouse eggs with somatic cells
Authors: Baranska Wanda , Koprowski Hilary 
Published: June 2005

AbstractThe purpose of these investigations was to study optimal conditions for the maintenance and stimulation of division of unfertilized mouse eggs in culture after fusion with somatic cells of various species origin.When unfertilized eggs obtained from superovulated C57B1/6 virgin mice were maintained in culture in Brinster's medium for 72 hours, less than 6% of the eggs divided. Following fusion in the presence of inactivated Sendai virus with somatic cells of mouse, hamster, monkey or human origin, 10 to 60% of the eggs divided, often developing to the early morula stage (3–10 cells).Blastomeres observed at this stage of development did not differ morphologically from embryo cells dividing after fertilization. Examination of autoradiograms obtained after fusion of eggs with labeled somatic cells support the belief that fusion may be a factor which initiates egg cell division. Ultimately, nuclei of the somatic cells inside the cytoplasm undergo karyorrhexis.Mouse fibroblasts infected with Moloney sarcoma virus fused better with egg cells than did non‐infected fibroblasts.
The influence of early extirpation of the otocysts on development of behavior of the chick
Authors: Decker John D. 
Published: June 2005

AbstractPrevious investigations have shown that through day 15 of incubation behavior of the chick was not influenced by sensory input. Behavior of chick embryos after this period has been reported to be controlled by integration of stimuli at centers located in different regions of the central nervous system. In this investigation experiments were designed to determine when sensory input of the vestibular system demonstrates an overt influence on the development of behavior and to determine how integration of stimuli at different levels of the CNS was affected by early extirpation of the otocysts.Unilateral and bilateral extirpations of the chick otocysts were made on day 3 or 4 of the incubation period. Embryonic motility was qualitatively and quantitatively monitored through 15 weeks post‐hatching. (Behavior of embryos was compared with unoperated controls and the ablated regions of the nervous system of experimentals were histologically compared with each other as well as with controls.)Primary losses of peripheral vestibular (inner ear) receptors and ganglia with little secondary degeneration of vestibular motor nuclei showed no influence on embryonic behavior until hatching. However, gross secondary degenerative changes of vestibular nuclei due to removal of the otocysts influenced behavior of the chick embryos around day 17. Presumably, the early acquisition of sensory capacity by the vestibular system does not influence the development of behavior until the end of the incubation period, but loss of interrelations between vestibular motor centers and other centers of the CNS influences behavior around day 17.
The electrophysiology of muscle fibers in the hearts of Decapod Crustaceans
Authors: Van Der Kloot William 
Published: June 2005

AbstractIntracellular recordings from the muscle fibers in contracting hearts of the crayfish and the lobster show a sequence of potential changes superficially resembling the vertebrate cardiac action potential. In the Crustaceans, however, the plateau part of the depolarization is produced by fused junctional potentials, elicited by the firing of motor neurons whose cell bodies lie in the cardiac ganglion. The first or second JP elicits an active membrane response that probably is produced by Ca2+ influx, since it is blocked by Mn2+. Local currents can flow between the individual muscle fibers, presumably by way of gap junctions. Simultaneous records were made extracellularly from one of the efferent nerves coming from the lobster cardiac ganglion and intracellularly from a muscle fiber. Four motor axons were identified in the efferent nerve and the firing of each of these sets up a JP at each point on the muscle membrane. A fifth motor neuron may also run to each muscle fiber. In the isolated heart the motor outflow from the cardiac ganglion is quite variable. Nevertheless, the system is such that the potential changes on the muscle membrane are almost indistinguishable from beat to beat. The hermit crab cardiac muscle usually has only two JPs per beat; the first JP sets up an overshooting spike.
Function of the pericardial sacs during the molt cycle in the land crab Gecarcinus lateralis
Authors: Mason Carol Ann 
Published: June 2005

AbstractThe hypothesis that the pericardial sacs of the land crab Gecarcinus lateralis directly take up and store proecdysial water has been investigated. At all stages of the molt cycle, the convoluted surface of the pericardial sacs apposed to the carapace forms a system of channels for capillary transfer of ground water to the gills. When exposed to an osmotic gradient in vitro, isolated intact pericardial sacs from normal or dehydrated intermolt, premolt, and postmolt crabs show no hydrosmotic response. Permeability to 3H2O (THO), expressed as hourly water exchange, is low for sacs under such conditions. If the separated old cuticle has been removed from sacs of late premolt crabs, up to 40 μl of water are gained in the first 15 minutes of exposure to an osmotic gradient, and the hourly exchange rate of THO is increased 30‐fold. These findings indicate that the pericardial sacs may allow osmotic entry of proecdysial water as detachment of the old cuticle takes place. From analyses of osmotic pressure, cations, and 14C‐insulin space of both hemolymph and pericardial sac fluid, it appears that the pericardial sacs do not store water per se but expand to accommodate an increasing hemolymph volume as proecdysial water enters the whole animal. Although water uptake occurs over a longer period in G. lateralis, the pattern of preparation for ecdysis is similar to that of all other brachyurans.
Environmental influence on experimental teratocarcinogenesis in testes of mice
Authors: Stevens Leroy C. 
Published: June 2005

AbstractTesticular teratomas were experimentally produced in mice of strains 129, A/He, and their F1 hybrids. When male genital ridges from 12‐ or 13‐day fetuses were grafted to various sites in adults, they developed into testes and some of them had teratomas. When male genital ridges were grafted into sites which descend into the scrotum, (the testis, the epididymis, or the epididymal fat pad of intact or castrate males), they developed into testes most of which contained teratomas. When genital ridges were grafted into sites which do not descend into the scrotum (the kidney, spleen, liver, cryptorchid testis, and ovarian fat pad) they developed into testes and most of them did not have teratomas. When genital ridges were grafted into intact females or into castrate females injected daily with peanut oil or with a physiological dose of testosterone proprionate, the incidence of teratomas was very low. These results are in accord with the hypothesis that the lower temperature in the scrotum promotes teratocarcinogenesis in grafted genital ridges. None of our results suggest that testicular or ovarian hormones of host origin are involved.
Hemocytes of saturniid silkworms: Their behavior in vivo and in vitro in response to diapause, development, and injury
Authors: Walters David R. 
Published: June 2005

AbstractThe blood of the wild silkworms Antheraea polyphemus, Samia cynthia, and Hyalophora cecropia (Lepidoptera; Saturniidae) contains two predominant classes of hemocytes, plasmatocytes and granulocytes, which are markedly different in their behavior. In diapausing pupae or developing adults, both types occur in nearly equal numbers. Following surgical injury there is a dramatic increase in the population of plasmatocytes. The behavior of the cells in vitro is not related to their origin but depends on the conditions of culture. In hanging drops the plasmatocytes clump together. On glass or plastic surfaces they become flattened and, like vertebrate fibroblasts, migrate apart to cover the surface with a sheet of cells. Identical cellular membranes from in vivo at wound sites. When dissociated fat‐body cells or tiny beads of resin are cultured in blood, the plasmatocytes adhere to them and draw them into large, heterogeneous aggregates. The granulocytes are completely passive in vitro under all conditions.
Division delays and abnormal oral development produced by colchicine in Tetrahymena
Authors: Nelsen E. Marlo 
Published: June 2005

AbstractThe effects of continuous colchicine treatment on cell division and oral morphogenesis were studied in synchronized Tetrahymena pyriformis GL‐C. The colchicine concentration used for most of this study, 4.0 mg/ml, was shown to have no effect on protein synthesis, as assayed by incorporation of C14‐leucine into hot TCA insoluble material. It was demonstrated that colchicine treatment produced agedependent division delays in Tetrahymena until a “transition point” was reached at about EST + 50−55 minutes, after which treatment produced a very little delay of division. Colchicine treatment prior to the transition point produced arrest or reversal of oral differentiation, followed by redifferentiation of abnormal structures in association with the delayed division. Treatment with colchicine after the transition point blocked oral development even though the cells continued to divide, which resulted in daughter cell with non‐functional oral strures. Under the assumption that colchicine specifically binds microtubule protein, it is suggested that assembly of microtubules prior to the transition point is required for both division and oral differentiation. After the transition point, microtubule formations is required for oral morphogenesis but not for cell cleavage.