bluuebunny/crossref_metadata_2025 huggingface dataset:
The development of the swim bladder of the Atlantic salmon
Authors: Hoar William S.
Published: February 2005

The anlage of the swim bladder of the Atlantic salmon arises as a small mass of undifferentiated cells resting dorso‐laterally on the posterior wall of the fore‐gut. This mound of cells is proliferated from the narrow band of mesoderm which lies between the epithelium and the serosa of the alimentary canal. The concentration thus formed elongates slowly for 11 weeks. At the end of this time an evagination from the lumen of the right side of the oesophagus grows into it. This tube commences to elongate rapidly just previous to the time of hatching, and reaches the posterior end of the body cavity at approximately the time when the young salmon emerge from the gravel. Throughout the fresh water life of the fish this organ is a relatively large thin walled sac, lying dorsal to the body cavity. Microscopic examination reveals layers typical of those of the digestive tract.
The structure of the nasal cavity in chamaeleo chameleon (Linnaeus)
Authors: Haas Georg
Published: February 2005

The nasal capsule of the chameleon differs greatly from that of other lizards in several respects. Cartilage is extremely persistent, particularly in the roof. The anterior chamber is produced backward to form an accessory posterior chamber. This posterior extension lies lateral to the olfactory chamber, from which it is incompletely divided by a longitudinal fold which may represent the normal concha.

The organ of Jacobson is extremely reduced and occupies an abnormal position with relation to other structures. The olfactory nerves and their branches are much reduced, and the olfactory epithelium is poorly developed. The chameleon is at best a microsmatic animal.
The liver‐blood fluid exchange and the morphology of hepatic cell mitochondria
Authors: Kater J. McA
Published: February 2005

This work was undertaken in an effort to determine the reason why the hepatic cell mitochondria of some animals show a structural response to adrenalin while others show no such reaction.

It was found that those animals whose mitochondria are altered by adrenalin undergo a relatively great increase in the percentage of water in the liver. This acquisition of fluid by the liver is accompanied by a disturbance of the cell‐plasma ratio of the blood. Those species whose mitochondria show no reaction to adrenalin have no change of volatile liver water, haematocrit reading, and probably have no change of total blood volume.
Certain reproductive organs in the Neritidae
Authors: Andrews E. A.
Published: February 2005

Descriptions and figures of the subordinate sex‐organs are given for thirty species taken at random throughout the entire family.

It is found: that the higher genera have organs not present in the lower; that they have a storage sac for mineral particles to be added to the secreted capsules within which the eggs will develop; that the anus is more or less fused to the mouth of the oviduct to allow of easy passage of the above materials from anus to oviduct; that spermatophores grade from simple elongated tubes of the lower to stout double tubes with various forms, with spicules, or with spirals, in the higher forms; that the sacs for holding the spermatophores may be simple, when the spermatophores are cast out after discharge, but are more evolved when spermatophores are to be permanently retained and digested; that while lower forms have no sex organs upon the head, peculiar organs occur in the higher genera, in one or both sexes.

These organs have value as aids in classification of genera within the family Neritidae. The very marked coordination among these organs may be better understood when further observation reveals how they are used in sperm transfer.
The effect of temperature on mitochondria in liver cells of fish
Authors: MaCcardle Ross C.
Published: February 2005

Fundulus and goldfish were subjected to varying degrees of temperature from 0° to 60°C. Heat rigor and lethal temperatures (37° to 40°C.) cause mitochondria to vesiculate, fragment, globulate and dissolve. The Golgi apparatus becomes swollen, breaks into small dictyosomes which migrate to the peripheral cytoplasm, and dissolves. Osmicated fat increases in amount. The vacuoles (vacuome) increase in number. Evidence is presented to show that dissolution of mitochondria takes place by three distinct methods; namely, (1) vesiculation, (2) fragmentation, (3) globulation. The mixochondriome hypothesis is proposed. This is based on the idea that the mitochondria differ in their chemical constitution, an idea which is supported by the fact that each kind of mitochondrion shows a characteristic manner of dissolution. It is believed that the semi‐lunar vesicles of goldfish liver cells are not of mitochondrial origin, and that they and the Golgi apparatus are concerned in fat formation.
The histogenesis of muscle in the regenerating fore limb of larval Amblystoma punctatum
Authors: Thornton Charles Stead
Published: February 2005

The 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

The 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

The 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

A 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

Analysis 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

This 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

The 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

This 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

Centrifuging 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

1. 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

In 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

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

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

The 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

Finding 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

At 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

The 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

In 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.
The motility of rabbit spermatozoa recovered from the female reproductive tract
Authors: Cooper G. W. , Overstreet J. W. , Katz D. F.
Published: February 2005

The motility of rabbit spermatozoa recovered from the vagina, endocervix, uterus, and four regions of the oviduct was assessed visually by phase‐contrast microscopy at intervals from one minute to 16 hours after a single mating. The percentage of motile cells in each sample was dependent on the temperature of recovery, ie, 23° vs 37°C, but was not influenced by the temperature of observation. Spermatozoa in the lower isthmus of the oviduct were the most temperature sensitive population to recovery at 23°C. When all manipulations and observations were performed at 37°C, the percentage of spermatozoa with progressive motility varied according to the region sampled and interval after mating. Populations from the vagina, uterus and upper regions of the oviduct usually had a high proportion of progressively motile cells with vigorous flagellar activity. Fewer spermatozoa showed progressive movement on recovery from the endocervix and lower 2 cm of the tubal isthmus and their flagellar activity was generally depressed. The decrease in flagellar beat frequency noted in the latter regions may be a major factor limiting sperm ascent in the female tract. A unique pattern of “activated” motility was seen exclusively in populations taken from the oviducts at 6 to 16 hours after mating. This motility pattern, consisting of alternating episodes of linear progressive and vigorous nonprogressive movement, may be analogous to the activated motility described for capacitated rodent spermatozoa.
Growth rate of oocytes in laboratory‐maintained Xenopus laevis
Authors: Keem Kirsten , Smith L. Dennis , Wallace Robin A. , Wolf Dennis
Published: February 2005

When female Xenopus laevis are injected with [3H]‐vitellogenin or [14C] N‐acetyl glucosamine, most of the labeled material becomes associated three days later with oocytes having a diameter of 0.9–1.1 mm; smaller and larger oocytes are less labeled. With time, the pattern of labeling shifts to larger oocytes, indicating that those oocytes initially labeled continue to grow. We have measured such shifts as a function of time to provide estimates for oocyte growth rates from the end of stage III (diameter = 0.6 mm) to stage VI (diameter = 1.2 mm). The total time required for oocytes to progress through this size increase is 16–24 weeks in unstimulated females and 9–12 weeks in human chorionic gonadotropin (hCG)‐stimulated females. The fastest rate of growth occurs from mid‐stage IV (approximately 0.8 mm diameter) until midstage V (1.2 mm diameter), which corresponds to the period of most pronounced vitellogenin uptake. The relative proportion of oocytes within this size range is also reduced, as predicted under steady‐stage conditions. Evidence is also presented which indicates that the steady‐state level of full‐grown oocytes is maintained by a combination of replenishment and atresia. These results provide the first description of the kinetics of oocyte growth in X laevis females maintained under normal laboratory conditions and should be useful for any considerations of macromolecular events occurring during oogenesis.
High prolactin level and double spermatozoa
Authors: Baccetti B. , Fraioli F. , Paolucci D. , Selmi G. , Spera G. , Renieri T.
Published: February 2005

In a man with a pituitary prolactin‐secreting adenoma almost only double spermatozoa were produced. These cells were almost completely enveloped in a unique membrane, a common bilocular acrosome capped two paired nuclei, and all the other organelles were double. After 120 days of treatment with 2‐brom‐α‐ergocryptine the prolactin level was corrected, and only normal, single spermatozoa were produced. The authors suggest that a high prolactin level inhibits cell division.
The structural organization of sperm chromatin
Authors: Young R. J. , Sweeney K.
Published: February 2005

The structure of rabbit, fowl, and Xenopus laevis sperm chromatin was explored by study of the reaction of their decondensed nuclei with DNase 1 and micrococcal nuclease. Those of rabbit and fowl were readily digested by DNase 1, and the polyacrylamide gel electrophoresis profiles of DNAs extracted from the digests were similar, each being polydisperse with a single discrete band of DNA smaller than 72 base pairs. There were differences, however, between the sperm chromatins in the course of their digestion by micrococcal nuclease. A limit digest at about 45% acid solubility was obtained with Xenopus sperm chromatin, while 90% of fowl sperm DNA was rendered acidsoluble by the enzyme. The gel profiles of the limit digests were polydisperse, but only those of rabbit and fowl sperm chromatins possessed a discrete band of DNA smaller than 72 base pairs. Bleomycin did not react with DNA of rabbit, fowl, or Xenopus spermatozoa. Since bleomycin reacts with somatic cell chromatin, and the course of DNase 1 or micrococcal nuclease digestion of sperm chromatin was different from that found for somatic cell chromatin, it would appear that sperm chromatin does not have the repeating nucleosometype structure of somatic cell chromatin. The nuclease digestion studies further suggest that the organization of rabbit and fowl sperm chromatins is similar, and is different from that of Xenopus sperm chromatin. The dependence of the structure of sperm chromatin on the composition of its basic proteins, and a possible structure for a protamine‐type sperm chromatin, are discussed.
Fertilizability of cryopreserved zona‐free hamster ova
Authors: Fleming Alan D. , Yanagimachi Ryuzo , Yanagimachi Hiroko
Published: February 2005

Mature unfertilized ova from superovulated hamsters were freed from all investments and frozen at −50°C. They were cooled at about 1°C/min to 0°C then at 0.8° to 0.6°C/min to −50°C. At 0°C, dimethyl sulfoxide was added to a final concentration of 1.25 M. The ova were stored at −50°C for up to four months. Thawing was performed at 2–4°C/min and followed by several washes with insemination medium. Approximately 90% of the ova were normal in appearance after thawing. The frozen and thawed ova with normal appearance could be penetrated by hamster or human spermatozoa at a rate comparable to unfrozen controls. The ability of hamster ova to tolerate storage at a relatively convenient temperature (−50°C) for long periods (tested for up to four months) makes possible their shipment at low cost to institutions lacking this resource. There they can be used for basic biological studies of sperm–egg interaction or in the clinical assessment of human sperm quality.
Fragmentation of condensed chromatin in nuclei of a plant sperm, pteridium aquilinum (L.) Kuhn
Authors: Wakeford R. J. , Bell P. R.
Published: February 2005

Nuclei of pteridium sperm have been dispersed by turbulence in natural or slightly alkaline buffer after stripping off the cytoplasm with nonionic detergent. The nuclei tended to break up into fragments arranged in a linear order. These fragments fluoresced brightly with acridine orange as did intact nuclei. Grounds are given for identifying the smaller fragments with chromosomes. It is proposed that the sperm nucleus of British Pteridium, possibly an autotetrapolid, consists of a sequence of paired homologues.
Genetic influences on mouse sperm capacitation in vivo and in vitro
Authors: Hoppe P. C.
Published: February 2005

Intial in vivo studies were performed to observe the proportion of eggs fertillized at specific intervals after natural mating and ovulation in our research mouse colony. Proestrous females of the C57BL/10Wt, SJL/Wt inbred strains and the F1 hybrid cross (B10 × SJL or reciprocals) were paired in the after‐noon with males of their respective strain and examined for vaginal plugs at the midpoint of the dark period (2400 hours). Oviducts were periodically collected from mated females, and ovulation was first observed at 4, 5.2, and 3 hours after 2400 hours in the B10, SJL, and F1 hyrid, respectively. The clutch of eggs from each ovulating female, was placed in culture, and cleavage oviduct lavage verifying female mating was placed in culture, and cleavage was used as the criterion for fertilizaition. Fifty percent of the eggs were fertilized 2.2, 5.0, and 2.5 hours after ovulation in B10, SJL, and F1 hybrid females, respectively. Because twice the legth of time was required to fertilize a similar proportion of eggs from the SJL strain as the F1 hybrid, these two strains were used for determining their rate of fertilization under more fully controlled conditions in vitro. Forty‐nine percent of F1 hybrid eggs were fertilized after 4 hours incubation with SJL epididymal sperm, whereas 53% fo SJL and 56% of F1 hybrid eggs were fertilized after only 2 hours incubation with F1 hybrid epididymal sperm. Thus, using sperm from these two mouse strains, the amount of time required to fertilize approximately 50% of the eggs within a clutch both in vivo and vitro was very similar. These observations demonstrte teh validity of using this in vitro system for fertilization studies and confirm that the temporal events in sperm capacitation and egg penetration are dependent on the genotype of the sperm. Similarities in fertilization rates at specific times after ovulation or insemination in vitro imply that the initiationof sperm capacitation in vivo occurs near the time of ovulation and several hours after mating. We tentatively suggest that follicular fluid may be required for completion of mouse sperm capacitaiton in vivo.
Decondensation of sperm nuclei of australian marsupials: Effects of air drying and of calcium and magnesium
Authors: Cummins J. M.
Published: February 2005

Spermatozoa of six species of Australian marsupials have been studied. The nucleus is highly unstable when compared with those of eutherian mammals. When thin films of spermatozoa in buffered saline are air‐dried on glass slides, the nucleus disintegrates and flattens, leaving the acrosome, midpiece, and tail intact. This spreading of the nucleus can be inhibited by seminal plasma proteins and by bovine serum albumin, but is potentiated by detergents. The nucleus also decondenses spontaneously in the presence of high concentrations (>0.25M) of calcium and magnesium salts, leaving the head membranes, acrosome, midpiece, and tail intact. This is inhibited by EDTA. In some species, certain areas of the nucleus appear more resistant t o Ca++/Mg++ treatment, and the initial stages of decondensation are uneven. Ultrastructurally the Ca++/Mg++ dispersed chromatin shows a moderately fine, branching, fibrillar structure, interspersed with dense granules. Treatment with disulphide bond cleaving agents together with detergents results in rapid and complete dispersal of the chromatin and acrosome, and slow digestion of midpiece and tail structures. Treatment with HCl, NaCl, KCl, EDTA, detergents, and sucrose has no effect on nuclear integrity, but treatment with NaOH (0.9–1.0M) results in complete digestion of the whole sperm. These findings are discussed in the light of evolutionary differences between marsupial and eutherian mammals in terms of sperm structure and composition.
An automated procedure to measure DNA synthesis in preimplantation mouse embryos
Authors: Cozad Karen M. , Verbanac Kathryn M. , Goldbard Simon B. , Warner Carol M.
Published: February 2005

This paper describes a sensitive, reproducible, and automated procedure to measure DNA synthesis in preimplantation mouse embryos. Conditions for the DNA synthesis assay have been optimized as follows: (1) 4 μCi/ml3H‐thymidine (sp. act. 20 Ci/immole); (2) a labeling period from 2 to 7 hours; (3) a 3‐hour preincubation period for blastocysts and from 0 to 7 hours preincubation for 8‐cell embryos; and (4) from 1 to 64 embryos per assay. The amount of DNA synthesis per embryo was found to be directly proportional to the number of cells (nuclei) per embryo. The described assay should be useful for future studies on the effect of synthetic and natural compounds on the development of preimplantation mouse embryos, as measured by perturbations in embryonic DNA synthetic activity.
Temperature dependence of capacitation in bat sperm monitored by zona‐free hamster ova
Authors: Lambert Hovey
Published: February 2005

The temperature dependence of capacitation in bat sperm (Myotis lucifugus lucifugus) was studied by monitoring fertilizations rates of zona‐free hamster ova at different temperatures. Spermatozoa were cultured in BWW medium at temperatures 4°C, 24°C, 32°C, 42°C, and 55°C from 0–24 hr. Activation of sperm could be determined visually due to the change in movement seen through light microscopy. Activation was later confirmed by higher rates of fertilization. Preincubation of the bat sperm was found to have a direct effect on the success of penetration of the zona‐free hamster ova. Holding bat spermatozoa at low temperature for long intervals allowed them to remain motile but unable to fertilize. Sperm are not irreversibly damaged, however, and activation, when the temperature is increased to 32°C, is faster than when sperm are intitially put at 32°C, resulting in good fertilization rates.
Inhibition of starfish oocyte maturation by some inhibitors of proteolytic enzymes
Authors: Kishimoto Takeo , Clark Theodore G. , Kondo Hisayo K. , Shirai Hiroko , Kanatani Haruo
Published: February 2005

Starfish oocyte maturation is triggered by a natural hormone, 1‐methyladenine (1‐MeAde), produced in the follicle cells, or artificially by dithiothreitol (DTT). These substances act on the oocyte surface to produce a cytoplasmic maturation‐promoting factor (MPF), which induces germinal vesicle breakdown (GVBD) and subsequent processes of meiotic maturation. Further, MPF is amplified in immature oocytes that have received the injection of MPF. In this paper the effect of leupeptin and antipain, protease inhibitors of microbial origin, on starfish oocyte maturation was investigated. The protease inhibitors were found to inhibit 1‐MeAde‐induced maturation when they were applied externally or injected into oocytes. DTT‐induced maturation was also inhibited by injection of leupeptin. However, leupeptin did not inhibit the maturation‐inducing action of MPF or MPF amplification. These results show that the protease inhibitors suppress the production of MPF by 1‐MeAde or DTT, suggesting that some endogenous protease(s) acts in the production of MPF.
Fertilization of cumulus‐free, zona‐intact mouse ova in vitro at high and low sperm concentrations
Authors: Stanger J. D. , Quinn P.
Published: February 2005

The effect of varying the sperm concentration between 2 × 105 sperm/ml and 8 × 106 sperm/ml on fertilization of cumulus‐free, zona‐intact F1 (CBA × C57BL) mouse ova by QS and F1 (CBA × C57BL) mouse spermatozoa was studied. The spermatozoa from both strains of mice exhibited optimal fertilization rates at 2 × 106 sperm/ml. However, at sperm concentrations greater than 4 × 106 sperm/ml and less than 1 × 106 sperm/ml, fertilization rates were significantly reduced. F1 spermatozoa were more susceptible to dilution than QS spermatozoa. A significant interaction between strain and sperm concentration indicated that the two strains produced different fertilization rates at different sperm densities.

Extracts of epididymal fluid, medium from capacitated spermatozoa, or ampulla fluid did not improve the fertilization rate at 2 × 105 sperm/ml, but retaining the cumulus oophorus did. The decrease in fertilization rate at 8 × 106 sperm/ml can in part be attributed to a nondialysable inhibitor from the neat sperm preparation that appeared to be of epididymal origin.
Evidence for acrosin‐like enzyme in sperm extract and its involvement in fertilization of the ascidian, halocynthia roretzi
Authors: Sawada Hitoshi , Yokosawa Hideyoshi , Ishii Shin‐Ichi , Hoshi Motonori
Published: February 2005

The presence of a protease has been demonstrated in sperm of the solitary ascidian, Halocynthia roretzi, by using t‐butyloxycarbonyl‐L‐Val‐L‐Pro‐L‐Arg‐4‐methylcoumaryl‐7‐amide (Boc‐Val‐Pro‐Arg‐MCA) and other arginyl or lysyl MCA derivatives as substrates. Several properties of the enzyme were investigated in a crude extract. The activity had a pH optimum near 8.0 and was enhanced by the addition of CaCl2. The Km value of 87μM was determined for Boc‐Val‐Pro‐Arg‐MCA under the optimal conditions. An apparent molecular weight was estimated to be 35,000 by gel filtration. The enzyme was inhibited with diisopropyl fluorophosphate, leupeptin, antipain, p‐aminobenzamidine, Val‐Pro‐Arg‐CH2Cl, and soybean trypsin inhibitor, but scarcely inhibited with chymostatin, elastatinal, p‐chloromercuribenzoic acid, tosyl‐Lys‐CH2Cl, and tosyl‐Phe‐CH2Cl. Boc‐Val‐Pro‐Arg‐MCA, the most susceptible of the substrates examined, showed the most effective inhibition against fertilization of ascidian eggs.

Thus, this enzyme in ascidian sperm extract has features closely similar to mammalian acrosin [EC 3.4.21.10], and we conclude that the enzyme is involved in fertilization as one of the lysins.
Ultrastructure of the biflagellate spermatozoon of tomopteris helgolandica greef, 1879 (annelida, polychaeta)
Authors: Franzén Åke
Published: February 2005

The spermatozoon of the polychaete Tomopteris helgolandica is of an aberrant type with two flagella, each measuring about 40μm. The nucleus is roughly conical and weakly bent. At the anterior end it is rounded and covered only by the nuclear and plasma membranes. Membraneous, electron‐dense structures are applied laterally to the nucleus. These structures may have a helical arrangement. The middle piece contains about ten mitochondria, two centrioles, and two centriolar satellite complexes. The centriolar regions are connected with the posterior part of the nucleus. The axonemes of the two tail flagella lack the usual central complex with central tubules, radial spokes, or related structures. No arms seem to be present on the A tubules of the doublets. In the middle piece the tail flagella are surrounded by invaginations of the plasma membrane forming flagellar canals. The sperm has a bilateral symmetry whereas the primitive sperm has a radial symmetry. The occurrence of two tail flagella in this spermatozoon has no phylogenetical connection with biflagellate spermatozoa in other animal groups. A series of mutations has resulted in the development of two flagella emerging from the two centrioles, the lack of a central complex in the axoneme, and the lack of a typical acrosome. In the Polychaeta, sperm structure is generally more related to function that to phylogenetics. During swimming the spermatozoon of Tomopteris rotates around its longitudinal axis.