bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fertilization of hamster eggs in vitro at sperm:Egg ratios close to unity
Authors: Bavister B. D. 
Published: June 2005

AbstractHamster epididymal spermatozoa were washed and preincu‐bated at extremely low sperm concentrations (100/ml or less) in a culture medium containing naturally‐occurring sperm motility‐stimulating substances. These substances were partially purified “sperm motility factor” (SMF) derived from hamster adrenal glands and catecholamines (epinephrine or isoprotere‐nol). After preincubation for three hours, a small number (5 or less) of washed, cumulus‐free hamster eggs was added to each sperm suspension. Many of these eggs were undergoing fertilization when examined two to three hours later. Fertilization was accomplished in vitro at sperm:egg ratios approaching 1:1, a situation comparable to that believed to exist in vivo. It appears that this demonstration will considerably enhance the potential of in vitro fertilization studies for providing useful information on mammalian gamete interactions.
Nuclear requirement for post‐maturational cortical differentiation of amphibian oocytes: Effects of cycloheximide
Authors: Schuetz Allen W. , Samson Douglas 
Published: June 2005

AbstractCycloheximide induced a complex series of alterations in the cortical cytoplasm of amphibian (Rana pipiens) oocytes undergoing steroid induced nuclear and cytoplasmic maturation in vitro. The morphological changes were described and the role of nuclear‐cytoplasmic interactions in the induction of these changes was investigated in intact, enucleated and enucleated‐reinjected oocytes. Three stages of cortical changes were ascertained on the basis of: localized alterations at the animal pole, redistribution of pigment and localized contractility (furrow formation) primarily along the animal:vegetal pole axis. The extent and type of cortical alterations varied depending upon the time at which oocytes were examined following hormonal stimulation and cycloheximide treatment. Cycloheximide did not produce cortical alterations in non‐hormone treated oocytes nor in steroid treated oocytes until after germinal vesicle breakdown. Nuclear and cytoplasmic maturation and the appearance of cortical alterations were all inhibited when cycloheximide was added to oocytes at the time of steroid treatment. Cycloheximide induction of cortical alterations occurred only after the inhibitor was no longer effective in preventing germinal vesicle breakdown.Enucleated oocytes underwent cytoplasmic maturation in response to the steroid but exhibited no cortical alterations following the delayed addition of cycloheximide. Simultaneous administration of cycloheximide and steroid to enucleated oocytes inhibited cytoplasmic maturation and all observable cortical alterations. Reinjection of nuclear material into enucleated oocytes restored the ability of cycloheximide to induce cortical alterations following steroid induction of cytoplasmic maturation. Without steroid treatment, such reinjected oocytes did not exhibit cortical changes in response to cycloheximide. The data demonstrate that the nucleus is required for and contains a factor(s) which controls the cycloheximide response and post‐maturation differentiation of the oocyte. The maturational changes in the cortical cytoplasm appear to be dependent on the intermixing of the germinal vesicle nucleoplasm materials with mature cytoplasm following germinal vesicle breakdown. The results further suggest that the cortical effects of cycloheximide are dependent upon the initiation of protein synthesis during this period of oocyte development. The significance of these observations and experimental studies are discussed in relation to current understanding of the molecular mechanisms controlling meiosis induction and the composition of the germinal vesicle.
Initial stages of sperm penetration into the egg of Fundulus heteroclitus
Authors: Brummett Anna Ruth , Dumont James N. 
Published: June 2005

AbstractVery little information is available about the morphological details of sperm‐egg fusion in teleosts. The acrosomeless teleost sperm gains access to the egg cytoplasm through a small opening (the micropyle) in the egg envelope (the chorion). Identification of the micropyle, therefore, permits one to localize the sperm entry site and to use the electron microscope to study the details of sperm‐egg fusion under normal monospermic conditions. In this study freshly stripped eggs of Fundulus heteroclitus were inseminated with sperm of the same species and exposed to fixative at intervals varying from 1 second to 15 minutes after insemination. The scanning electron microscope was used to observe morphological aspects of the initial stages of fertilization.
Neural regulation of cholinesterase in newt skeletal muscle. II. The effects of denervation and of culture in vitro
Authors: Rathbone Michel P. , Vickers John D. , Ganagarajah Mailvaganam , Brown Judy A. , Logan David M. 
Published: June 2005

AbstractThe effect of denervation in vivo on the acetylcholinesterase (AChE) of newt (Notophthalrnw uiridescens) triceps muscle was compared with the effect of culturing explanted muscles in organ culture. Two weeks after denervation, the AChE activity of triceps muscles falls to approximately 60% of that in innervated muscles. The initial rate of loss of AChE is more rapid during summer than during winter, but no seasonal differences were observed in the specific activity of AChE in innervated muscles or in muscles two weeks after denervation. Changes in AChE activity when the triceps muscles were maintained in organ culture were similar in rate and in extent to those that occurred after denervation in vivo.The effect of denervation in vivo and culturing upon the individual AChE species separated by velocity sedimentation was also determined. Denervation and organ culture both resulted in a marked and rapid loss of two forms of AChE with sedimentation coefficients of 16.5S and 12.8S on sucrose density gradients. The former is associated with the motor endplates and the latter with the musculotendinous junctions. The activity of another form of AChE, with a sedimentation coefficient of 9.8S, transiently increased after denervation, but after one week returned to the initial level. The activity of a major form of AChE, with a sedimentation coefficient of 5,5S, remained constant after denervation, but that of the slowest sedimenting form (3.7S) declined slightly after one week. Similar alterations in the activities of these forms were observed in cultured muscles. Co‐culture of the muscles with dorsal root (sensory) ganglia from newts prevented both the loss of total AChE activity and the alterations in molecular forms of AChE in the muscles. This innervation‐like effect of the ganglia is apparently mediated by a diffusible factor(s) since ganglia separated from the muscles by a Millipore filter (0.22 μm pore size) also prevented alterations in AChE activity and molecular forms in the cultured muscles.These results demonstrate that the response of AChE to the absence or presence of nervous tissue, apparently mediated by a neurotrophic factor, is identical to that observed in vivo, at least in the case of the characteristics examined.
Failure of human spermatozoa to penetrate zona free mouse and rat ova in vitro
Authors: Quinn P. 
Published: June 2005

AbstractWhen incubated for 8 to 26 hours with zona‐free mouse or rat ova, human spermatozoa failed to attach to or penetrate any of the ova. The ova were capable of being fertilized since both intra‐ and inter‐species penetration of spermatozoa and formation of pronuclei occurred between rat and mouse gametes. When mouse spermatozoa were incubated for three to eight hours with rat ova, a high proportion of the ova were penetrated, formation of pronuclei occurred and in 9 out of 36 ova incubated for 40 hours after insemination, regular cleavage and formation of morphologically normal 2‐cell embryos occurred. Human spermatozoa retained their morphological integrity and motility only when the culture medium contained purified bovine serum albumin (3 mg/ml) or human serum (5% v/v) and not when unpurified BSA from several different commercial sources was used as a protein source. In this latter medium, the ova of both rats and mice degenerated after 8‐hour incubation in the presence of human spermatozoa but not when human spermatozoa were absent or in the presence of either rat or mouse spermatozoa. Electron microscopy indicated that the human spermatozoa incubated for eight hours in medium containing purified BSA had undergone an acrosome reaction. These spermatozoa also attached to and penetrated human oocytes which had been matured in vitro.
Short period interspersion pattern in the genome of a teleostean fish
Authors: Serra Virginia , Mandarino Rosina 
Published: June 2005

AbstractSequence interspersion in the genome of Salmo trutta has been investigated by means of reassociation kinetics of DNA fragments of 0.5 and 2.5 Kb double‐stranded fragment lengths. Preliminary results indicate that only 34% of the trout genome presents a short period interspersion pattern, the remainder seems to be composed of unique and repeated sequences longer than 2.5 Kb.
Salt and water balance in the oligohaline clam, Rangia cuneata II. Accumulation of intracellular free amino acids during high salinity adaptation
Authors: Henry Raymond P. , Mangum Charlotte P. , Webb Kenneth L. 
Published: June 2005

AbstractDuring adaptation to an increase in ambient salinity (2–20 ppt) the estuarine clam Rangia cuneata enlarges the pool of free amino acids in adductor muscle fibers by more than five‐fold (>300 μM/gm dry wt). The process can occur under anaerobic conditions, but oxygen is critical to survival during high salinity adjustment. It is suggested that the pool may be enlarged by de novo synthesis, via a modified form of glycolysis perhaps involving the direct amination of pyruvate to form alanineutilizing free ammonia.
Ovarian development in an opportunistic breeder, the Zebra Finch Poephila guttata castanotis
Authors: Sossinka Roland 
Published: June 2005

AbstractIn opportunistic breeding species living in unpredictable environments, gonadal development and activation should be quite different from that in periodically breeding species, which live in an environment with highly predictable changes. In Australian Zebra Finch females, bred in laboratories, the development during ontogeny was investigated. Body growth, ovarian weight, and the diameter of the largest follicle were recorded in birds 10 days to some years of age. A linear follicle growth pattern from 10 to 100 days is followed by a resting phase, during which the follicles remain in a medium‐developed resting state. As soon as favorable conditions occur, a rapid logarithmic growth and yolk deposition starts, leading to ovulation within one to two, weeks. Egg laying sometimes occurs as early as day 90. The ovary as a whole reaches a medium‐developed resting state much later, but remains in this state even during long nonbreeding intervals.Compared with photoperiodically breeding species, for example Zonotrichia leucophrys gambelii, the Zebra Finch has the disadvantage of permanently keeping its gonads activated. Because of the lack of proximate factors, the Zebra Finch has to respond to the appearance of the ultimate factors as quickly as possible. Activation of fully regressed ovaries would take too much time, but starting from a medium‐developed resting state allows ovulation in less than two weeks. In addition, no detectable refractory period reduces the capacity to respond. In the young this causes precocity.These peculiarities have been selected for by the sporadic and erratic rainfalls, which cause the unpredictability of breeding periods in several parts of Australia.
Effect of hydrostatic pressure on morphogenesis in nerve‐free hydra
Authors: Wanek Nancy , Marcum Beverly A. , Lee Hsueh‐Tze , Chow Margaret , Campbell Richard D. 
Published: June 2005

AbstractTissue stretching was controlled in hydra which lack nerves by preventing the accumulation of osmotic fluid within the gastrocoelic cavity. Hydra lacking nerves (epithelial hydra) became highly distended and swollen during the course of regular daily culturing conditions. Animals that were kept deflated for several days lost some of the abnormal morphology characteristic of epithelial hydra. The hypostome became conical and the upper portion of the body column became constricted. These new, more normal characters persisted for two days after deflation was discontinued. After long term deflation, the mesolamella was thick and regions of peristaltic annulations were altered. Furthermore, animals failed to bud at normal rates or elongate when pressure, in the gastric cavity was continually low. Thus, hydrostatic pressure, arising from gastrocoelic fluid, affects the long term histological and morphogenetic organization of hydra tissue.
Development of Drosophila imaginal discs in vitro: Effects of ecdysone concentration and insulin
Authors: Martin Presley , Shearn Allen 
Published: June 2005

AbstractA detailed scoring system was used to determine the effects of a variety of factors on the evagination and differentiation of Drosophila imaginal discs cultured in vitro. In modified Schneider's Drosophila medium, β‐ecdysone induced development at concentrations approximately 100x lower than α‐ecdysone. The metamorphosis of imaginal discs consists of two processes, evagination and differentiation, which were found to be differentially sensitive to hormone concentration. Optimal differentiation occurred at relatively low β‐ecdysone concentrations (30 ng/ml), while complete evagination required higher levels (500 ng/ml). Even at the optimal hormone concentration for differentiation, not all discs differentiated completely, and each region of the eye, antenna, wing, and leg exhibited a characteristic frequency of differentiation. In addition, a strong negative correlation between the extent of evagination and the quality of differentiation was observed. Bovine insulin stimulated β‐ecdysone induced evagination, but at the same time it inhibited differentiation.
Partial blastema formation after amputation in adult mice
Authors: Neufeld Daniel A. 
Published: June 2005

AbstractThe amputation surface of toes of adult mice was treated by repeated skin removal and exposure to a saturated solution of NaCl. Histological examination of treated appendages revealed the presence of wound epithelium, numerous irregularly oriented subepithelial cells, many of which were mitotically active as indicated by [3H] thymidine uptake, and a remodeled viable bone adjacent to subepithelial cells. Thus, tissues at the amputation site of mammals can resemble comparable tissues of newt limb stumps at an early stage of regeneration. Complete blastema formation was not achieved, however.
Chicken fetal antigen expression on the definitive erythroid maturation series in the bone marrow of the adult chicken
Authors: Nelson Carrie H. , Patel Nipam H. , Sanders Bob G. 
Published: June 2005

AbstractChicken fetal antigen (CFA) describes a membrane developmental antigen system present on embryonic and fetal erythroid cells that is present during development, but is absent on erythrocytes of mature chickens. In this study, CFA was detected by indirect immunofluorescence and correlated with six stages of morphological maturation of erythroid cells. All cells in the erythroid series through the late polychromatic erythrocyte (reticulocyte) stage were found to posses CFA. Fluorescent intensity and staining patterns of the definitive erythroid series demonstrated CFA concentration increase and distribution pattern change throughout erythroid maturation.
Molecular correlates of morphological differentiation: Avian scutes and scales
Authors: Brush Alan H. , Wyld Jean A. 
Published: June 2005

AbstractThe scute reticulate scales of birds differ morphologically. We present evidence that the differences extend to the level of molecular content and organization. From the molecular evidence it appears that the scute was derived from the crocodilian scale and that the reticulate scale, like the feather, may be a structure unique to birds.
The relation of mitotic index, cell density, and growth to pattern regulation in regenerating Ambystoma maculatum forelimbs
Authors: Stocum David L. 
Published: June 2005

AbstractMitotic index and cell density were determined for all stages of larval Ambystoma maculatum upper arm and wrist regeneration up to the notch. Intrinsic growth rates and proportions of skeletal segments of upper arm and wrist regenerates were determined for stages of regeneration from notch to 25 days post‐amputation. Mitotic index was always higher in the blastema of the regenerate than in the dedifferentiating tissue proximal to it. Mitotic activity along the proximal‐distal axis of the blastema proper was relatively uniform until the onset of redifferentiation, when it declined in a distal to proximal direction in the proximal half of the blastema. Cell density tended to parallel mitotic index in both wrist and upper arm regenerates. There was no evidence that apical growth of the blastema is controlled by an inverse relationship between cell density (contact inhibition) and mitotic index. The relationship between the intrinsic growth rates of the regenerating skeletal segments were such that the proportions of the segments remained unchanged throughout their redifferentiation in upper arm regenerates, but were shifted slightly in wrist regenerates. These findings are discussed in relation to the progress zone model of limb development (Summerbell et al., '73).
The follicular envelope of ascidian eggs: A site of messenger RNA and protein synthesis during early embryogenesis
Authors: Jeffery William R. 
Published: June 2005

AbstractSpawned ascidian eggs are surrounded by an extra‐embryonic envelope that consists of test cells and follicle cells and remains closely associated with the developing embryo until the time of larval hatching. The purpose of the present study was to determine whether this envelope is involved in macromolecular synthesis during early embryogenesis. Autoradiographic detection of radioactive uridine and leucine incorporation into the egg envelope of Ciona intestinalis and Styela plicata showed that this structure was active in RNA and protein synthesis between fertilization and the sixteen‐cell stage. In both ascidian species the components of the envelope active in macromolecular synthesis were the follicle cells. As shown by in situ hybridization with an [3H]‐poly (U) probe, the follicle cells but not the test cells contained substantial accumulations of poly(A)‐containing RNA during embryogenesis. Approximately 90% of the RNA synthesized in the follicle cells was poly(A)‐containing RNA. Both follicle cells and test cells, however, participated in macromolecular synthesis during oogenesis. The follicle cells of unfertilized Ciona eggs primarily synthesized a 42,000 molecular weight polypeptide which may be coded for by a major 16S putative mRNA species. It is concluded that the follicle cells are active in RNA and protein synthesis during early ascidian development. The production of a major polypeptide species suggests an active physiological role for these cells during embryogenesis.
Effect of thyrotropin‐releasing hormone on 22Na uptake by the pond snail Helisoma carabaceum
Authors: Grimm‐Jørgensen Y. 
Published: June 2005

AbstractThe effect of thyrotropin‐releasing hormone, added to the external environment, on in vivo Na+ uptake by Helisoma carabaceum was assessed. It was found that 10−5M TRH significantly decreased unidirectional sodium flux. The Na+ concentration in the tissues and hemolymph was not affected by the hormone. Histidyl‐proline‐diketopiperazine, a TRH‐metabolite, had no effects on Na+ uptake in vivo.
Surface properties of the zona pellucida
Authors: Phillips David M. , Shalgi Ruth M. 
Published: June 2005

AbstractStructural and sperm binding properties of the hamster zona pellucida (ZP) were investigated using the scanning electron microscope (SEM). The internal and external surfaces of the ZP were found to be morphologically dissimilar. The external surface displayed a fenestrated lattice‐like appearance, whereas the internal surface showed a regular rough appearance. In order to investigate the physiological characteristics of the ZP, zonae were incubated with in vitro capacitated spermatozoa for five minutes and subsequently prepared for SEM examination. Numerous non‐acrosome‐reacted spermatozoa and dissociated acrosomes were observed associated with the external surface of the ZP. Spermatozoa or acrosomes were, however, not observed associated with the internal surface of the zona. Acrosome‐reacted spermatozoa did not adhere to the ZP. It was concluded that the external and internal surfaces of the zona are morphologically and physiologically dissimilar.
A study of morphology of Caenorhabditis elegans: A mutant of Caenorhabditis elegans with dumpy and temperature‐sensitive roller phenotype
Authors: Hosono Ryuji 
Published: June 2005

AbstractThe wild‐type nematode Caenorhabditis elegans has an elongated and spindle‐shaped body, whereas the dumpy mutant has a shorter body with approximately the same diameter. Although the wild‐type nematode moves forward by producing sinusoidal waves along the body, the roller mutant moves by rotating the body left or right around its long‐body axis. A temperature‐sensitive morphological mutant which develops into an adult with dumpy phenotype, at 15°, but with roller phenotype at 25°, in addition to dumpy phenotype, was isolated. The dumpy phenotype appeared at the first larval stage and was complete at the fourth larval stage; the roller behavior was also expressed at the fourth larval stage. The heterozygous offspring (F1), produced by crossing the mutant hermaphrodite with wild‐type males, were rollers in both hermaphrodites and males. Therefore, the dumpy character is autosomal recessive, and the roller character is dominant in heterozygote but cold‐sensitive in homozygote. The dumpy mutation was mapped as allele of dpy‐10 gene of linkage group II (LG II). The F2 progeny, produced by self‐fertilization of the F1 roller hermaphrodite, segregated to wild, dumpy, and roller animals in a ratio of 1:1:2. An attempt to isolate from the F2 generation the roller mutant which produced no dumpy progeny was entirely unsuccessful. Therefore, the dumpy and the roller phenotypes are produced by closely linked mutations or perhaps by a single mutation.
Histochemistry of lobster claw‐closer muscles during development
Authors: Ogonowski M. M. , Lang F. , Govind C. K. 
Published: June 2005

AbstractBased on histochemical detection of the specific activities of myofibrillar ATPase in fast and slow mucle, the fiber composition of the paired claw‐closer muscles in the lobster Homarus americanus was examined during development. The cutter muscle of juvenile lobsters, 1 year (13th stage) and older, has a majority of darkly staining, fast fibers and a minority of lightly staining, slow fibers which are restricted to the ventral area. The crusher muscle, on the other hand, stained lightly over its entire area, showing that it is composed only of slow fibers. In the 3rd larval stage the paired muscles are similar, each having a central band of intense‐staining, fast fibers sandwiched by light‐staining, slow fibers. From the 4th stage onwards, the differentiation to the dimorphic condition occurs with gradual expansion, in the cutter claw of the dark‐staining, fast fibers, and in the crusher claw of light‐staining, slow fibers. The cutter closer muscle is differentiated completely and consistently by the 9th–10th stage, whereas the crusher differentiated more slowly between the 13th–22nd stages. During this process the transformation of slow muscle to fast in the cutter claw may be via an intermediate type.