bluuebunny/crossref_metadata_2025_split huggingface dataset:
The histogenesis of muscle in the regenerating fore limb of larval Amblystoma punctatum
Authors: Thornton Charles Stead 
Published: February 2005

AbstractThe regeneration of muscle in larval Amblystoma punctatum is preceded by an extensive dedifferentiation of the old muscles of the limb stump. The process of muscle dedifferentiation consists in a separation of muscle nuclei, surrounded by a small amount of cytoplasm, from the injured ends of the muscle fibers. The dedifferentiation of the cut muscles of the limb stump progresses proximad as far as the origin of the muscles on the humerus and results in a complete transformation of these muscles into undifferentiated cells which appear to contribute to the formation of the regeneration blastema. Shoulder muscles, which were attached to the humerus, also undergo a partial dedifferentiation when their points of insertion on the humerus are destroyed by the degeneration of the perichondrium. These muscles never dedifferentiate, however, for more than one‐fourth their original length. The process of dedifferentiation in the shoulder muscles is similar to that found in the cut muscles of the limb stump.The regeneration of the injured muscles occurs in two ways. The shoulder muscles reconstitute themselves by means of terminal and lateral sarcoplasmic buds formed near the distal regions of the muscle fibers. The muscles of the limb proper, distal to the shoulder, differentiate out of local aggregations of blastema cells. No myoblasts were observed.The regeneration blastema arose chiefly from dedifferentiated cells of muscle, nerve connective tissue sheath, perichondrium and cartilage.
Development of the gonads and gametes in the soft‐shell clam (Mya arenaria)
Authors: Coe Wesley R. , Turner Harry J. 
Published: February 2005

AbstractThe clam Mya differs from other pelecypods which have been investigated in this respect in having most of the reserve nutritive materials formed within the vacuolated follicle cells of the gonads instead of within the very limited amount of mesenchymatous connective tissue of the visceral mass. The profusely branching tubular gonads originate from two groups of primordial germ cells situated in the position of the future genital apertures. The germinal primordia soon become differentiated into two types of nuclei, one of which becomes associated with the large, vacuolated follicle cells, which form the principal volume of the gonadal tissue, while the other type proliferates to form the primary gonia which become widely scattered along the walls of each alveolus.There is much degeneration and cytolysis during gametogenesis in both sexes, with the accumulation of characteristic inclusions within the follicle cells. Atypical spermatogenesis followed by cytolysis occurs throughout the year but the normal method only in preparation for spawning. No evidence of protandry or change of sex was obtained; only three hermaphrodites were found in the examination of more than 1000 individuals.
Morphogenesis of the architecture of hip and thigh
Authors: Howell A. Brazier 
Published: February 2005

AbstractThe original innominate bone consisted of ischiopubis only. From this developed a dorsally‐directed ilium, upon which the dorsal limb muscles, originally arising from fascia, settled, and which thrust dorsalward between roots of the limb plexus, thus dividing the nerves into prozonal (dorsal and ventral) and metazonal (dorsal and ventral) groups. The primitive muscles of the tetrapod hip and thigh comprised a dorsal mass, soon divisible into sheets, innervated by both prozonal and metazonal dorsal nerves, and a similar ventral mass comparably innervated. The original two elements thus became four basic elements, and probably in early mammals or mammal‐like reptiles all dually innervated muscles split into singly innervated units. With this four‐group basis as the chief criterion, but considering other factors as well, it is possible to homologize the muscles of urodeles (ventral components only), lacertilians, mammals, and birds in entirely satisfactory manner, except for doubt in several instances in which specialization has secondarily obscured the precise relationships. In different mammals there is shown a tendency toward a final fusion of certain unrelated muscle units (biceps plus gluteus longus, human type of biceps, adductor magnus, and tensor fasciae femoris with gluteus maximus).
The histogenesis of the regenerating fore limb of larval Amblystoma after exarticulation of the humerus
Authors: Thornton Charles Stead 
Published: February 2005

AbstractA new limb skeleton will form in regenerating limbs of the larval Amblystoma in which the humerus had been completely removed. The cartilage of the new limb skeleton develops out of a blastema in which there are no cells of cartilage origin. This regeneration blastema is a composite structure made up of cells derived from a dedifferentiation of the injured tissues of the limb. The tissues which have been observed as contributing to the regeneration blastema are: muscles, especially the muscles of the shoulder; connective tissue of the sheath of the brachial nerve plexus; muscle connective tissue; and, to a certain extent, subcutaneous connective tissue. The new cartilage of the limb skeleton develops out of this composite blastema by means of a differentiation of cells in the central axis of the blastema.The amount of cartilage regenerated appears to depend on the mass of the blastema. When the blastema does not extend fully into the glenoid cavity of the scapula, the head of the developing humerus is deficient in size and structure. However, a complete limb skeleton is regenerated when the blastema does extend fully into the glenoid cavity.Since the new cartilage of the regenerated limb has no genetic continuity with the old limb skeleton, it would appear that the limb field exerts some kind of histogenetic determining action.
Variation in bone length and limb proportions in the coot (Fulica americana)
Authors: Engels William L. 
Published: February 2005

AbstractAnalysis of measurements of the trunk region of the vertebral column and of the various segments of the wing and leg skeleton in sixty‐four specimens (thirty‐four males, thirty females) of Fulica americana shows that: The males average about 7% larger (longer) than females in all parts of the skeleton; the difference is uniform throughout the body. The coefficient of variability ranges from about 3.00 (humerus, et al.) to about 5.00 (hind toe). The correlation between lengths of parts is very high between different segments of the wing skeleton, or of the leg; it is somewhat less between homologous segments of the wing and leg; and it is still less between limbs and trunk. This decreasing order of correlation indicates an increasing order of independence of variability. The wing proportions in Fulica are those characteristic of the type of flight called flatterflug. The proportions of the leg are those of a bird moderately adapted for cursorial locomotion; the very long toes characterize a swimming bird.
Notes on the brain case of a therocephalian
Authors: Olson Everett Claire 
Published: February 2005

AbstractThis study is based on serial sections of the occipital and otic regions of a therocephalian from the Tapinocephalus zone. The occipital region as preserved consists of the basioccipitals and exoccipitals. The basioccipital is long and slender and is separated from the more anterior basisphenoid by an unossified zone. The exoccipitals are large and contain a part of the jugular foramen and two foramina for cranial nerve XII.The otic bones are fused together to form a periotic. The most striking feature of the inner ear is the medioventral position of the vestibule. Passing back into the periotic from the vestibule is a deep recessus scala tympani. This recess opens anteriorly into a ventral fenestra in the vestibule, the fenestra rotunda. These structures are similar to those of Dimetrodon and the gorgonopsian.The anterior part of the periotic is projected ventrally to form a basicranial process. This probably arose by intramembranous ossification. The unossified zone between the basioccipital and basisphenoid may represent a persistent basicranial fenestra.
Seasonal changes in the testis of the musk turtle, Sternotherus odoratus L.
Authors: Risley Paul L. 
Published: February 2005

AbstractThe spermatogenetic cycle of the testis of the musk turtle is limited to the summer months of the year, and closely parallels that of the anuran Amphibia. Spermatozoa are present in the testis from September to May, and breeding may occur in either fall or spring. A pronounced increase in the size of the epididymis and a corresponding decrease in the size of the testis occurs at the end of the cycle (September).During the months of March, April and May, all spermatozoa are eliminated from the seminal tubules, and the germinal epithelium is built up in preparation for spermatogenesis. Spermatogonial divisions occur in small numbers in May, and the division tempo increases during June. Primary spermatocytes and maturation divisions appear after the middle of June, and continue through July and August. Spermiogenesis begins in late July, is in full progress in August, and is practically completed by October. Laboratory specimens usually show an active spermatogenesis in winter, but it is not probable that a second spermatogenetic cycle occurs in specimens under normal hibernating conditions.No seasonal changes are observed in the interstitial cells of the testis, and no seasonally variable secondary sex characters are known for turtles. Special studies of the problem are being conducted.
Sexual phases in the gastropod Crucibulum spinosum
Authors: Coe W. R. 
Published: February 2005

AbstractThis species represents a typical example of protandric consecutive sexuality, the male phase becoming functional at a very early age, when the body has reached a length of only 3 to 7 mm. Those males which become functional earliest usually seek the association of older individuals in the female phase; others, maturing later, are more likely to remain solitary. Mated males have accentuated masculine characteristics and retain the male phase longer than solitary individuals or those that are isolated experimentally. Unfavorable environmental conditions postpone or prevent functional sexuality and terminate the male phase promptly without inaugurating the female phase. The influence of the female in accentuating the sexuality of the male is thought to be due to stimuli received by the latter through sense organs in tentacles and penis and mediated by the nervous system through hormonal secretions. Termination of the male phase and transition to the functional female are comparable to metamorphosis from the immature to the mature condition in other animals and, like metamorphosis, the primary (male) sexual phase can be abbreviated or prolonged experimentally, but the sequence cannot be reversed.
Pigmentation changes in tadpoles of Rana pipiens following centrifugation during the early gastrula
Authors: Beams H. W. , King R. L. 
Published: February 2005

AbstractCentrifuging the eggs of Rana pipiens in the early gastrula stage prevents the formation of the hypophysis in some of the tadpoles. The absence of the melanophorotropic hormone normally secreted by the hypophysis seems to be responsible for the contraction of the pigment cells. In addition, there are actually fewer pigment cells present in both the dermal and epidermal layers of the light tadpoles than there are in the controls. The paleness, therefore, of the tadpoles seems to be due to both a contraction of the pigment cells present and to an actual reduction in their number. The failure of the hypophysis to develop was brought about by centrifuging at an earlier stage in development of the embryo than in previous extirpation studies. The effects produced by centrifuging that are responsible for the failure of the hypophysis to develop are unknown. However, it is suggested that interference in some way with the presumptive hypophysis‐forming tissue has resulted in an inactivation of its inductive potencies.
The prostomial glands of the Indian leech, Hirudinaria granulosa
Authors: Bhatia M. L. 
Published: February 2005

Abstract1. The prostomial glands, as described by Bourne, are deep‐lying and unicellular, are distinctly different from the salivary glands, and their contents do not stain with boraxcarmine. They are ectodermal in origin.2. The material for the cocoon is secreted by the clitellar glands, while the prostomial glands secrete the yellowish plugs at the two poles which close the two ends of the cocoon.3. A fortnight after the cocoons are formed, the plugs become detached, leaving two outlets one at each pole, for the young leeches to wriggle out of the cocoon.4. The detachable plugs are possible only if not made of the same material as the cocoon.
Notes on the retinae of two opossum genera
Authors: Walls G. L. 
Published: February 2005

AbstractIn Didelphis virginiana and Marmosa mexicana the retina is sauropsidan in type and the eye as a whole is markedly adapted for scotopic vision. The superior half of the fundus of Didelphis is occupied by a tapetum lucidum of the retinal type, formed by the enlarged pigment epithelial cells which are devoid of pigment and packed with reflective particles of unknown composition. Such a tapetum is unique among mammals—in all known sub‐mammalian retinal tapeta the reflective material is guanin and is occusible in bright light by migratory fuscin. The retinal capillaries in Didelphis extend to the external limiting membrane, apparently in adaptation to the low permeability of the dense tapetum. Only four other mammals are known to have such capillaries and no inclusive explanation seems to hold for all. Didelphis possesses an ‘area centralis of sensitivity’ associated with the tapetum. Both genera have abundant rods and scanty cones, of three types. The oil droplets of the droplet‐bearing single cones and the double cones are colorless and the double cone contains only one, not two as reported by O'Day for other marsupials; nor are the members of the double cone ever alike in size and form. Opossum double cones are thus perfectly orthodox; primitive placental mammals should be examined for double cones and oil droplets.
Graduates as strategic change agents in small firms: a case study of graduate placements and lifelong learning
Authors: Jones Anne , Woods Adrian , Coles Anne‐Marie , Rein Melanie 
Published: February 2005

Abstract

Small and medium‐sized enterprises (SMEs) are often resistant to the employment opportunities offered by skilled graduates.
The Centre for Lifelong Learning at Brunel University ran a two‐year project aimed at encouraging local SMEs to consider unemployed graduates as suitable new employees through short‐term placements.
The concept of workplace‐based learning was introduced into firms by the graduates acting as strategic change agents.
A valuable learning experience can be gained by both small firms and graduates searching for work experience through the brokerage role of a university.
There is a limit to the impact of external factors in generating organizational changes in small firms.

Copyright © 2001 John Wiley & Sons, Ltd.
In pursuit of change: managerial constructions of strategic intent
Authors: Pitt Martyn 
Published: February 2005

Abstract

This article examines how managers conceptualize change‐directed strategic intent using a metaphoric approach.
Managers draw on experience and intuition as well as rational evaluation to construct intent, which can be captured holistically via expressive action metaphors. Several of these are drawn from the strategy literature.
Two managers are presented as case examples. A few significant metaphors appear to characterize their respective intents for strategic change. Both similarities and contrasts emerge, suggesting the merit of analysing strategic intent in this way.
Managers should try to be aware of their guiding metaphors and the impact of these on colleagues. Potent metaphors, especially ones that encode the personal priorities of senior managers, can become taken for granted, difficult to change and ultimately inappropriate.
A dominant metaphor can be highly motivating but possibly dysfunctional too. Conversely, multiple metaphors may result in ambiguity and confused priorities for action. Ways of coping with these dilemmas are suggested.
Metaphors of intent need exposing and exploring in open debate to achieve widespread commitment. Therefore, change agents should encourage colleagues to explore new metaphors collectively and to interpret their nuances in order to create imaginative, counter‐ intuitive and particularized prescriptions for effective and advantageous strategic change.

Copyright © 2001 John Wiley & Sons, Ltd.
The effects of diets containing different levels of common vetch (Vicia sativa) seed on fattening performance, carcass and meat quality characteristics of Awassi male lambs
Authors: Gül Mehmet , Akif Yörük M , Macit Muhlis , Esenbuga Nurinisa , Karaoglu Mevlut , Aksakal Vecihi , Irfan Aksu M 
Published: February 2005

AbstractThe experiment was carried out to evaluate the effect of common vetch seed (CVS), used at various levels (0, 15 and 25%), as a protein source in diets replacing different proportion of barley, wheat bran and soybean meal on fattening performance, carcass and meat quality characteristics of Awassi male lambs at approximately 8 months of age. The lambs were divided into three treatment groups, T1 (control, fed a diet without CVS; n = 12), T2 (15% CVS; n = 12) and T3 (25% CVS; n = 12), at the beginning of the fattening period. The T2 and T3 lambs were fed with a concentrate including 15 and 25% of ground CVS. The main protein source was soybean meal in T1 diet treatment, partially replaced by vetch in T2 and T3 diet treatments. All groups were fed a diet consisting of concentrate mixture offered ad libitum, and 300 g of grass hay per lamb per day during the 60 day fattening period. Daily feed intake, daily weight gain and feed conversion efficiency (concentrate and hay consumption for 1 kg of live weight gain) were 1.716 kg, 0.26 kg and 6.60 for T1, 1.756 kg, 0.28 kg and 6.27 for T2 and 1.806 kg, 0.29 kg and 6.23 for T3, respectively. Growth, carcass and meat quality traits were almost the same across the groups. In conclusion, CVS supplementation to diets of Awassi lambs at a 0, 15 and 25% rates showed no statistical differences in fattening performance, wholesale cuts of carcasses, meat color parameters (L* = lightness, a* = redness, b* = yellowness, H = huge angle and C = chroma) and pH values, but there were numerical differences (improvement) in feed conversion efficiency. Copyright © 2005 Society of Chemical Industry
Flavour compounds of Greek cotton honey
Authors: Alissandrakis Eleftherios , Kibaris Athanasios C , Tarantilis Petros A , Harizanis Paschalis C , Polissiou Moshos 
Published: February 2005

AbstractFinding marker compounds is a powerful tool in the determination of the botanical origin of honey. For this purpose the flavour fraction of Greek cotton honey was investigated. A striking characteristic of this type of honey is the presence of more than 35 phenolic compounds in the extract, accounting for almost 60% of the total amount of compounds positively identified by gas chromatography/mass spectrometry. In comparison with honeys of nine different origins, a total of 15 compounds could serve as potent markers for cotton honey, namely cinnamaldehyde (0.44%), cinnamyl alcohol (1.79%), cinnamic acid (1.13%), neryl and geranyl nitrile (0.16 and 0.41% respectively), benzenepropanol (0.5%), homovanillyl alcohol (0.6%), (E)‐ and (Z)‐p‐methoxy‐cinnamic acid (0.48 and 0.14% respectively), 2‐methyl‐p‐phthalaldehyde (0.22%), coniferaldehyde (0.47%), p‐coumaric acid (1.77%), ferulic acid (0.51%), scopoletin and scoparone (0.47%). Copyright © 2005 Society of Chemical Industry
An immunocytochemical localization of the cortical granule lectin in fertilized and unfertilized eggs of xenopus laevis
Authors: Greve L. Carl , Hedrick Jerry L. 
Published: February 2005

AbstractAt fertilization, the vitelline envelope surrounding the egg of Xenopus laevis is modified by the addition of an electron‐dense component termed the “F layer.” The F layer functions as a block to polyspermy and as a block to the escape of macromolecules from the perivitelline space, thereby causing an osmotically driven envelope elevation. F‐layer formation has been hypothesized to result from interaction between a cortical‐granule lectin, released in the cortical reaction, and a jelly‐coat ligand. Evidence for this hypothesis was sought by determining the location of the cortical‐granule lectin both before and after fertilization, using a specific antibody conjugated to horseradish peroxidase. The cortical‐granule lectin was localized only in the cortical granules of the unfertilized egg and was located predominantly in the perivitelline space and the F layer of a fertilized egg. These observations support the hypothesis that the F layer is formed by a cortical‐granule‐Iectin–jelly layer‐ligand interaction.
Surface topography of mouse eggs before and after insemination
Authors: Nicosia Santo V. , Wolf Don P. , Mastroianni Luigi 
Published: February 2005

AbstractThe surface configuration of zona‐free mouse ovarian eggs before and after germinal vesicle breakdown (GVBD) and of tubal eggs before and after insemination was studied by scanning electron microscopy. The surface of germinal vesicle‐intact eggs was characterized by uniformly distributed, dense (2–3μm2 and slender (0.1 × 0.8μm) microvilli. Following GVBD, the mouse oolemma underwent dramatic changes which persisted essentially unmodified in uninseminated tubal eggs. These changes consisted of an apparent conversion of the oolemma from a microvillar to a smooth or ruffled configuration with approximately two ruffle‐like micro‐projections (0.6 × 0.4 μm) perμm2 of surface. In most eggs, both ruffled and smooth configurations ere present, creating dramatic polarities in surface topography similar to those documented previously by TEM [Nicosia et al, 1977]. Following insemination and presumed sperm–egg fusion, microvilli reappeared either from smooth areas or from the upper edge of ruffled microprojections. Zona removal appeared to induce limited reduction in the size of microvilli in some eggs. The present results emphasize the labile and dynamic nature of the egg surface and suggest a close relationship among nuclear, cytoplasmic, and surface events during the final stages of egg maturation and during fertilization.
Neck region of gerbil spermatozoa
Authors: Chakraborty Jyotsna 
Published: February 2005

AbstractIn the course of the reorganization and degeneration of the proximal centriole in the mature acentriolate spermatozoon of the Mongolian gerbil, both the proximal and distal centrioles appear in the early cap phase of spermatid development. During the acrosome phase, both distal and proximal centrioles become highly active in the formation of a segmented column. The proximal centriole becomes actively involved in the formation of the capitulum, while the distal centriole forms the axonemal complex and dense fibers. During the maturation phase of spermatid development, the “pinwheel” arrangement of the proximal centriole becomes an “S”‐shaped structure, turned 90° on its vertical axis. The few “doublet” microtubules that can be detected later in that stage completely disappear during spermiation. The distal centriolar area develops a single central pair of microtubules and membranous elements. Another prominent feature in the neck region of the gerbil spermatozoa is the presence of two dense rudimentary columns in association with the mitochondria. Although their density is similar to that of the other columns, these two columns have no connection with the dense fibers; in fact, they are closely associated with the mitochondria.