bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of duct ligation on the fertilzing ability of spermatozoa from different regions of the rabbit epididymis
Authors: Bedford J. M. 
Published: June 2005

AbstractIn the normal rabbit, fertile spermatozoa first appear in the lower half of the corpus epididymidis. If sperm passage is impeded in the low corpus region, the capacity to fertilize and initiate normal ovum development can ultimately arise in sperm withheld in any part of the ductus epididymidis, distal to the caput flexure. Sperm released from the initial part of the epididymis proximal to the caput flexure did not fertilize, even though many showed apparently normal progressive motility twelve and one‐half to fifteen days after low corporeal ligation. Since these infertile, motile sperm did not show the normal head–head agglutination reaction of mature rabbit sperm in a medium containing serum, it appears that the dichotomy between motility and fertilizing ability may have been at least partly due to the persistence in an immature state of the sperm plasma membrane.Many caput sperm which displayed normal sustained motility had retained the cytoplasmic droplet in the neck region, whereas, in others showing comparable motility, the droplet had moved along the midpiece or had been lost. It, therefore, seems unlikely that movement and loss of the droplet can be of importance in development of the capacity for motility in maturing spermatozoa.
Studies of the melanogenic response of regenerating feathers in the weaver bird: Comparison of two species in response to two gonadotrophins
Authors: Ralph C. L. , Grinwich Daniel L. , Hall Peter F. 
Published: June 2005

AbstractThe gonadotrophic hormones, interstitial cell‐stimulating hormone (ICSH, also known as luteinizing hormone) and pregnant mare serum (PMS), stimulate melanogenesis in regenerating feathers of weaver birds. In experiments designed to explore the mechanism by which these hormones stimulate melanogenesis, a method was devised for examining feathers microscopically, soon after injection of the gonadotrophic hormone. The two hormones were compared and two species of weaver bird, namely Euplectes after and Steganura paradisaea, were used for this comparison. In response to both hormones, melanocytes began to appear in the feathers of Steganura 12–24 hours after injection, but it was not until about 30–54 hours that they could be seen in feathers of Euplectes. ICSH induced a transient proliferation of melanocytes, higher doses causing responses of longer duration but generally not lasting more than 24 hours. In contrast, the responses to PMS continued for at least 72 hours in Steganura and for at least 96 hours in Euplectes. The possible significance of these observations is discussed in relation to the mechanism by which the hormones stimulate melanogenesis in feathers.
Hormonal regulation of feather pigmentation in African weaver birds: The exclusion of certain possible mechanisms
Authors: Ralph C. L. , Grinwich Daniel L. , Hall Peter F. 
Published: June 2005

AbstractAn earlier paper (Hall et al., '65) presented evidence to show that in producing pigmented feathers in the weaver bird, interstitial cell‐stimulating hormone (ICSH or LH) does not act locally upon the feathers. The present paper describes our further search for the site of action of the hormone. It is concluded as the result of these experiments that ICSH is unlikely to act via the hypothalamus, the adrenal, the thyroid or the pineal. Evidence is also presented to suggest that synthetic α‐MSH does not produce black feathers and that extensive damage to the pituitary (short of total destruction) by means of electrocautery does not alter the response to ICSH. The site of action of ICSH in producing pigmented feathers remains unknown but the possibilities are now reduced.
In vitro fertilizaton and the sperm acrosome reaction in the hamster
Authors: Barros C. , Austin C. R. 
Published: June 2005

AbstractThe feasibility of procuring fertilization of ovulated hamster eggs in vitro with epididymal spermatozoa has been confirmed, and additional evidence is brought forward to show that a period of just under four hours is needed for sperm capacitation in vitro.It has also been found that follicular eggs can be fertilized in vitro with epididymal spermatozoa, and at a higher incidence than ovulated eggs. Female tract secretion in the hamster therefore play no unique role in sperm capacitation or sperm penetration into eggs.A close correlation, both in time and the nature of effective media, existed between the acquisition of fertilizing capacity by spermatozoa and the occurrence of the sperm acrosome reaction. The highest incidence of spermatozoa showing the acrosome reaction was seen when the cells were incubated in the contents of mature follicles; the incidence was lower with the contents of part‐grown follicles and with the secretions of the Fallopian tube. Neither the egg nor its investments appear to be the source of significant amounts of the agent or agents responsible. Induction of the acrosome reaction by follicular contents showed partial species specificity. No reactions were seen with homologous aqueous humor and fluid hen egg‐white.From observations on the frequency of polyspermy and numbers of supplementary spermatozoa it is inferred that the efficiency of both the zona reaction and the block to polyspermy increases during preovulatory follicular enlargement to reach a peak during the first 2 or 3 hours after ovulation.
Regional influences on development of the single comb primordium
Authors: Lawrence Irvin E. 
Published: June 2005

AbstractIn an effort to resolve some of the developmental controls in single comb morphogenesis, comb primordia from New Hampshire Red and White Leghorn chick embryos were excised and grafted in atypical positions. The grafts were allowed to develop and recognizable structural details were later recorded and analyzed.Four different experimental series were made: (1) defect, i.e., the comb primordium was excised and the embryo developed with deficiency; (2) orthotopic, i.e., donor primordium grafted to frontonasal process of host; (3) heterotopic, i.e., donor primordium grafted to neck region of host; and (4) chorioallantoic, i.e., entire primordium grafted to chorioallantoic membrane of host chick. The promordia ranged in developmental age from stage 9 to stage 29.The results showed that the comb primordium can self‐differentiate. Single comb primordia of the White Leghorn breed are determined for comb by stage 15. The primary source of comb tissue appears to be local in origin. Regional influence of growing structures seems to affect comb form. When grafted in most regions and positions, the developing comb did not grow in length. Neck grafts which included some beak tissue developed elongate and typical comb. Rostral extension of the nasal and interorbital septum around seven days of development is thought to be important in normal elongation. Complex clusters of points developed in neck grafts that did not elongate. The normal distribution of comb components was not seen in such grafts. Form of blade and points appears to be predetermined.The conclusion is made that the capacity to differentiate comb form, e.g., ridge, axes, and regional divisions with or without serrations is fixed within the cell population that will form comb by stage 15; distribution of the structural components and typical elongation can be modified through tissue interactions in later stages.
Histological and ultrastructural study of the muscular and nervous systems in Hydra. II. Nervous system
Authors: Davis Lowell E. , Burnett Allison L. , Haynes Julian F. , Osborne Dallas G. , Spear Mary Lou 
Published: June 2005

AbstractNerve cells in hydra have been studied with the light and electron microscopes. Techniques for observing bi‐polar, tri‐polar, multi‐polar and sensory cells are described. Evidence is presented that these cells form a major part of the nervous system in hydra.The ultrastructural studies indicate the following: (1) There are three types of nerve cells: ganglionic, sensory and neurosecretory. (2) Nerve cells are concentrated at the base of tentacles, hypostome and basal regions. (3) Nerve cells are situated adjacent to the muscle fibers of the epithelio‐muscular cells. Criteria for identification of nerve cells at the ultrastructural level are presented. The nerve cells in hydra appear to be structurally different from similar cells in higher invertebrates and vertebrates. An important distinction is the lack of specialized synaptic vesicles in hydra.The appearance, dimensions, and location of secretory droplets in cells identified as neurosecretory cells are discussed. The droplets resemble closely neurosecretory droplets in nerve cells of higher invertebrates and vertebrates. The mechanism for the release of neurosecretory material in hydra appears to be similar to that suggested for higher organisms.It is suggested that one type of secretory droplet in hydra nerve cells may represent a growth stimulating principle that is believed to control growth and differentiation (Burnett, '66). The relationship of nerve cells to muscle processes is discussed.
The dynamics of stolon elongation in the hydroid, Campanularia flexuosa
Authors: Wyttenbach Charles R. 
Published: June 2005

AbstractStolon elongation in Campanularia has been shown to occur in cycles, each consisting of the following phases: (a) extended and resting, (b) retraction, (c) retracted and resting, (d) re‐extension to the length in phase (a), (e) resting, and (f) extension. Three features of this cycle — cycle duration, magnitude of extension and magnitude of retraction — have been evaluated to determine their inherent constancy and their modification by environmental and other factors.In the strain studied, cycle duration was a highly reproducible 6.15 ± 0.05 minutes at 20° C, consistent both from cycle to cycle in a given stolon, and among different stolons. This time is most markedly affected by temperature but is also genetically regulated within moderate limits and is affected to a small degree by the organic content of the sea water.Extension per cycle averages 20 μ (about 5.0 mm daily) in most older stolons, though individual cycles vary randomly from this mean by ± 20%. This average varies considerably among different genetic stocks, is less in newly‐initiated than in older, establised, stolons and is markedly reduced at temperatures exceeding 22° C. It is remarkably resistent in established stolons to all but severe starvation.The magnitude of retraction is highly variable (1 to 28 μ) from cycle to cycle, though this variation occurs in a predictable fashion. Evidence is presented that the extent of retraction is determined by the degree of internal hydroplasmic pressure behind the tip.Isolated stolon tips 300–500 μ long (diameter about 200 μ) display all essential features of the normal growth cycle. Such rhythmic activity is therefore intrinsic to the cells at or within 0.3 mm of the tip. Effects exerted by more distant regions may modify but do not basically change this pattern.Synchronized with this elongation cycle is a cycle of thinning and thickening of the epidermal layer at the stolon tip. Thinning is interpreted as a passive response to the forward thrust of the gastrodermis.
Effect of low nutrition on size of striated muscle fibres in the mouse
Authors: Rowe R. W. D. 
Published: June 2005

AbstractInbred, male 129/Re mice were maintained on a low plane of nutrition for a period of 21 days. After this time they were sacrificed and the following five muscles were examined for total fibre number and fibre diameter distributions, anterior tibialis, biceps brachii, extensor digitorum longus, soleus and sternomastoideus. Changes in body weight and muscle weight were also recorded.The low plane of nutrition resulted in a significant body weight loss (30%) and variously decreased muscle weights. The ratios, muscle weight: body weight, however, were higher in the experimental mice. The total fibre numbers of the muscles were not affected by the plane of nutrition. The mean fibre diameters of all the muscles, except the soleus, were lower in the experimental mice. These lower values were brought about by a decrease in the proportions of fibres of large diameter and not by the reduction in diameter of all the fibres.It was concluded that a low plane of nutrition caused fat deposits to be depleted, thereby reducing the body weight and the work‐load of the phasic muscles, i.e., muscles bringing about body movements. This enabled the muscles to be effective at a smaller size. The level of muscle growth was adjusted at the individual fibre level.
The morphogenetic movements at the lower surface of the blastodisc in salmonid embryos
Authors: Ballard William W. , Dodes Lance Meredith 
Published: June 2005

AbstractPatterns of hitherto undescribed morphogenetic movements have been found in Salmo gairdneri and Salvelinus fontinalis by removing samples of blastodiscs from their yolk spheres at intervals of several hours and inspecting their lower surfaces. Before onset of epiboly, the former species usually produces no pregastrular subgerminal cavity, but the latter usually produces one or several, with wide variation. In both species the inner blastomeres consolidate from an earlier dispersed and migratory condition, forming a coherent flattened sheet 6 to 10 cells thick before active epiboly begins.As the first evidence of polarity in the salmomd embryo, one sector of the blastodisc becomes condensed and slightly thickened. Then a broad central area of the disc rapidly thins out as a result of two types of movement: (1) large numbers of cells disengage from the under surface of the condensed blastodisc, and they migrate away from the center as individuals and small groups; (2) the rest of the internal cells engage in a similar centrifugal movement toward the germ ring and the embryonic shield, but as a coherent sheet, sliding just within the cellular envelope.Some, perhaps all, of the disengaged cells of the first group are slowly gathered into the endoderm sheet. The coherent cells of the second group accumulate in germ ring and embryonic shield, where they become split temporarily into upper and lower sheets, the former adhering to the external layer, the cellular envelope, with which it forms the epiblast, and the latter associating with the disengaged cells as the hypoblast.The first internal sign of axis formation is a hitherto undescribed nubbin of cells attaching to the yolk syncytium at one sector on the inside of the blastodisc rim. The nubbin cells take no further part in the epibolic spread of the disc. It is suggested that they from an anchor for the later convergence movements from right and left, and that the whole pattern of movements from then on may be controlled by a gradient of increasing cell adhesiveness that spreads from them as a center. These nubbin cells have never been at the surface of the blastodisc. They neither invaginate nor migrate forward. They may represent the prechordal plate.
Sex hormone induction of sex reversal in the goldfish and evidence for male heterogamity
Authors: Yamamoto Toki‐O , Kajishima Takao 
Published: June 2005

AbstractMethyltestosterone and estrone were administered orally to fry of the goldfish, Carassius auratus, daily for two months; thereafter, they were raised on a normal diet. All but one of the methyltestosterone‐treated fish developed into males, while all estrone‐treated fish developed into females. Of seven methyltestosterone‐treated males mated with normal females, six produced progeny in a 1 ♀:1 ♂ ratio and the remaining one produced only females. Of eleven estrone‐treated females mated with normal males, seven produced progeny in a 1 ♀:1 ♂ ratio and four yielded offspring in a ratio of 1 ♀ : 3 ♂. Induction of sex reversal in both directions by heterologous sex hormones was successfully accomplished. The sex ratios of the progeny of hormone‐treated goldfish provide evidence that the male is heterogametic (XY).
Water balance of whole animal, muscle tissue, and muscle cells in the prosobranch gastropod, Acmaea scutum
Authors: Webber H. H. , Dehnel Paul A. 
Published: June 2005

AbstractThe prosobranch limpet Acmaea scutum is found in both marine and estuarine environments. A number of parameters affect the water balance of this limpet. A. scutum has little control of total water content. Total water changes with season, size of animal, and salinity. Limpets from a marine environment, when immersed in experimental salinities for up to one week, are unable to regulate total body water. Estuarine limpets however, are able to regulate total body water in experimental salinities between 24 and 48 hours immersion. The ability to regulate water content between 24 and 48 hours is probably not important in the estuarine environment. Studies on the effect of field salinity on the water content of estuarine animals show that changes in field salinity of about 15% sea water resulted in significant changes in total body water.Water content of muscle tissue and muscle cells of marine A. scutum, like body water values, conform when external salinity is changed. Estimates of intracellular water per unit of muscle tissue (using inulin space as extracellular space) changed with external salinity from 79.3% at 50% sea water to 57.7% at 125% sea water.
Effect of temperature on early embryological development of the zebra fish, Brachydanio rerio
Authors: Schirone Robert C. , Gross Leo 
Published: June 2005

AbstractThe early development of the zebra fish embryo, Brachydanio rerio (Hamilton) was studied under thermostatically controlled temperatures ranging from 13° to 35°C. Regular and successive cleavages and a distinct continuity of morphological features proceed regularly between 23° and 34°C. Embryos kept at temperatures above or below these limits did not complete embryogenesis. Embryogenesis up to late high blastula proceeded at the same rate of development over the temperature range of 24°C to 32°C.Time‐lapse cinephotomicrography was utilized in a study of development from the one‐celled blastodisc to the closure of the blastopore, incubated in a modified Rose culture chamber. The number of abnormal embryos was constant over the range of temperatures from 23° to 34°C.
The effect of zinc on sea urchin morphogenesis
Authors: Timourian H. 
Published: June 2005

AbstractEmbryos of the sea urchin Lytechinus pictus were incubated for different periods of time in various concentrations of ZnCl2 in artificial sea water at pH 7.0 and 7.8. In general, zinc treatment restricts the development of endoderm and mesenchyme derivatives and zinc may be classified as an animalizing substance. The specificity of the zinc effects is analyzed considering the time during development that 65Zn is taken up by the embryo and the possible effects of zinc on protein synthesis, cell division and cell migration. The possibility that zinc exerts its effect non‐specifically as a toxic substance is explored. The animalizing properties of zinc may be the result of a non‐specific arrest in development at the time when the structures derived from the vegetal half are differentiating.
The development of the serosa in male embryos of the mealy bug, Pseudococcus obscurus Essig
Authors: Bregman Allyn A. 
Published: June 2005

AbstractThe development of the serosa or embryonic covering is described for males of the coccid, Pseudococcus obscurus Essig. The cells of part of this tissue are typical of males, having the paternal chromosome set heterochromatic and genetically inert. The cells of the remainder of the tissue have the chromosome contributions of both parents in the euchromatic state. Observations on cells undergoing reversal from the heterochromatic to euchromatic state are described. Euchromatic serosa cells (ESC) were selectively damaged or destroyed by (1) paternal x‐irradiation (PI) causing genetic damage to one set, (2) direct ultraviolet irradiation of ESC, and (3) interspecific mating to introduce foreign genetic information. The effects of these treatments on serosa composition were studied. Following PI, the fewer ESC were usually not accompanied by more heterochromatic serosa cells (HSC). After UV irradiation, the fewer ESC were consistently accompanied by extra HSC. Following interspecific mating, the hybrid ESC resembled those of the maternal species, Ps. obscurus, in number and size, but the HSC increased in number. Within almost all groups, regardless of treatment, a negative correlation between the numbers of ESC and HSC was found. The negative correlations and the UV results support an area compensation model for the completion of the serosa. The model is that a change in the total area of the ESC is accompanied by a compensatory change in the total area of the HSC. The results of PI may be consistent with the model since the size of individual ESC increased.
Effects of estrogen, progesterone, and testosterone on the pituitary and ovary of catfish, Heteropneustes fossilis (Bloch)
Authors: Sundararaj Bangalore I. , Goswami Shashi V. 
Published: June 2005

AbstractEstradiol benzoate (EB), testosterone propionate (TP) and progesterone have been administered orally over 45 days during the late preparatory period to intact female catfish showing ovarian recrudescence. EB or TP treatment brings about a reduction in the size and number of basophils in the pituitary, and inhibition of vitellogenesis in the ovaries. Progesterone administration causes partial ovarian regression without significantly altering pituitary cytology. The sexually dimorphic urogenital papilla which is inconspicuous and nonmuscular in the female is unaffected by hypophysectomy and/or EB treatment. TP induces complete masculinization of the female papilla, whereas progesterone is only marginally effective.EB injections over 15 days to intact catfish having ovaries containing yolk laden oocytes induce significant reduction in the number of pituitary basophils and extensive follicular atresia in the ovaries. Administration of EB to hypophysectomized catfish inhibits hypertrophy of the granulosa cells surrounding the yolky oocytes and thus delays the impending follicular atresia. The significance of these findings is discussed.
Isolation and characterization of ribosomal ribonucleic acid from the crustacean, Gecarcinus lateralis
Authors: Skinner Dorothy M. 
Published: June 2005

AbstractMethods for the isolation of ribosomal RNA (rRNA) from three crustacean tissue have been devised. These include precipitation of rRNA from total RNA preparations with 1M sodium chloride, to remove both melanin and ATP, or solubilization in buffer containing EDTA, to chelate Mg++ and Ca++ which, when present, form alcohol‐insoluble complexes with ATP. By cosedimentation or gel electrophoresis with rRNA of known S20, w, the sedimentation constants of crab rRNA have been determined to be 28 S and 18 S. The base compositions of the 28 S and 18 S rRNA's have been determined. Muscle, midgut gland and epidermis have been found to have higher concentrations of rRNA in the premolt period than in the intermolt period, with the maxima corresponding to the periods of maximum protein synthesis. Premolt epidermis has the highest rRNA content of the three tissues.