Structure, ultrastructure et essai d'interprétation fonctionnelle de l'appareil génital femelle d'Hemidiaptomus ingens provinciae et de Mixodiaptomus kupelwieseri (Copepoda, Calanoida). II. L'aire génitale

1989 ◽  
Vol 67 (10) ◽  
pp. 2579-2587 ◽  
Author(s):  
Corinne Cuoc ◽  
Jean Arnaud ◽  
Michel Brunet ◽  
Jacques Mazza
Keyword(s):  
Seminal Receptacle ◽  
Outer Part ◽  
Ventral Side ◽  
Egg Laying ◽  
The Other ◽  
Circular Section ◽  
Genital Segment ◽  
Genital Area ◽  
Double Function

The genital area in Hemidiaptomus ingens provinciae and Mixodiaptomus kupelwieseri is made up of several external and internal solidary cuticular components, which connect the genital ducts with the outside. Its outer part, which is located on the ventral side of the genital segment, is delimited by an ovoid cuticular fold and by two swelling processes, one dorsal and the other ventral. The center is occupied by two operculums, which are separated from a median wall by two crescent-shaped genital apertures. The inner part of the area essentially includes two U-shaped ducts by which the oviducts are connected to the genital apertures. During egg laying, to allow oocytes and oviductal secretions to be carried out through the genital apertures, the ducts take a more or less circular section, owing to the contraction of muscles attached to their wall. At this stage, the genital area is entirely masked by a temporary external seminal receptacle. The genital area assumes a double function in reproduction: first, in stocking spermatozoa in the seminal receptacle, and second, in allowing oocyte laying and fecondation as they are pushed into the ovisac.

Functional morphology and taxonomic relevance of the female genital structures in Acartiidae (Copepoda: Calanoida)

1999 ◽  
Vol 79 (5) ◽  
pp. 857-870 ◽  
Author(s):  
R.-M. Barthélémy
Keyword(s):  
Functional Morphology ◽  
Seminal Receptacle ◽  
Egg Laying ◽  
The Other ◽  
Storage Site ◽  
Complex Organization ◽  
The Family ◽  
Almost All ◽  
Scanning Electron ◽  
Female Genital

Observations of female genital structures using light and scanning electron microscopy in 25 species of Acartiidae (Copepoda: Calanoida) show the presence of paired gonopores and egg-laying ducts with a typical semicircular configuration in all specimens. In the genus Acartiella, there is no seminal receptacle and the external genital area serves as storage site of the spermatophoral products forming an external mass. Unlike in the other acartiids, the genital structures present a complex organization with paired adjacent gonopores and copulatory pores. In almost all the species, the seminal receptacles exhibit characteristic loop-shaped seminal ducts which connect them to the egg-laying ducts. The functional morphology and taxonomic relevance of genital structures are discussed. The present results do not justify the Steuer's subgenus division of the genus Acartia, the very predominant one of the family.

scholarly journals Phenology of two interdependent traits in migratory birds in response to climate change

2015 ◽  
Vol 282 (1807) ◽  
pp. 20150288 ◽  
Author(s):  
Nadiah Pardede Kristensen ◽  
Jacob Johansson ◽  
Jörgen Ripa ◽  
Niclas Jonzén
Keyword(s):  
Climate Change ◽  
Resource Availability ◽  
Migratory Birds ◽  
Egg Laying ◽  
The Other ◽  
Sufficient Evidence ◽  
Hatching Date ◽  
Arrival Date ◽  
Body Of Knowledge ◽  
Asynchronous Hatching

In migratory birds, arrival date and hatching date are two key phenological markers that have responded to global warming. A body of knowledge exists relating these traits to evolutionary pressures. In this study, we formalize this knowledge into general mathematical assumptions, and use them in an ecoevolutionary model. In contrast to previous models, this study novelty accounts for both traits—arrival date and hatching date—and the interdependence between them, revealing when one, the other or both will respond to climate. For all models sharing the assumptions, the following phenological responses will occur. First, if the nestling-prey peak is late enough, hatching is synchronous with, and arrival date evolves independently of, prey phenology. Second, when resource availability constrains the length of the pre-laying period, hatching is adaptively asynchronous with prey phenology. Predictions for both traits compare well with empirical observations. In response to advancing prey phenology, arrival date may advance, remain unchanged, or even become delayed; the latter occurring when egg-laying resources are only available relatively late in the season. The model shows that asynchronous hatching and unresponsive arrival date are not sufficient evidence that phenological adaptation is constrained. The work provides a framework for exploring microevolution of interdependent phenological traits.

The fine structure of the PD proprioceptor of Cancer pagurus II. The position sensitive cells

1973 ◽  
Vol 184 (1075) ◽  
pp. 199-205 ◽  
Keyword(s):  
Fine Structure ◽  
Ventral Side ◽  
The Other ◽  
Maximum Sensitivity ◽  
Narrow Neck ◽  
Cancer Pagurus ◽  
Canal Cell ◽  
Position Sensitive ◽  
Physiological Differences ◽  
Different Levels

The cell bodies of the position sensitive units form a row distal to the movement sensitive cells and their dendrites run in pairs in a narrow neck of tissue on the ventral side of the receptor strand. The scolopidia share the features of elongation and relaxation sensitive movement units. Thus the canal cell is absent, but there is some scolopale material in the enveloping cells. Also the scolopale is apposed by a mixture of strand cells and collagen. The more distal scolopidia are found in a region of large haemocoelic lacunae. The physiological differences between movement and position sensitive units could be explained in terms of how well the dendrites are anchored into the tube; with the position cells possibly being held at different levels with respect to their maximum sensitivity. On the other hand, the dendrites of both types of unit may behave identically and, if so, then the necessary physiological differences could occur in the transduction and/or impulse initiation sites. These alternative explanations are discussed.

An Account of Larval Budding in the Compound Ascidian, Hypsistozoa fasmeriana

1959 ◽  
Vol s3-100 (52) ◽  
pp. 575-589
Author(s):  
BERYL I. BREWIN
Keyword(s):  
Neural Tube ◽  
Ventral Side ◽  
The Other ◽  
Free Swimming ◽  
Close Link ◽  
Bud Formation ◽  
Maximal Size ◽  
The Right ◽  
Sexually Mature ◽  
Posterior Position

Larval budding in Hypsistozoa fasmeriana is in many ways unique in the sub-family Holozoinae. The stolon, which projects from the left side of the oozooid, is large (235 µ in diameter, 1.8 mm in length) and reaches maximal size before severance of buds occurs. The buds arise one at a time and 9 to 14 are formed. Test forms rapidly between a newly severed bud and the remainder of the stolon. Thus the buds are moved along an arc of a spiral which runs from the left side of the oozooid somewhat anteriorly across the ventral side and posteriorly up the right side. By the end of bud formation the first-formed bud occupies the most posterior position, lying high up on the right side of the oozooid. Each larval bud develops directly into a blastozooid and by the time the tadpole becomes free-swimming there is a considerable degree of organogenesis. The blastozooids together with the oozooid form a ring of zooids tilted slightly away from the vertical. After metamorphosis of the tadpole this ring becomes horizontal, but the tilt is still maintained with the oozooid occupying the most elevated position. Thus in the young colonies the plane of the head is slightly off the horizontal--an arrangement which persists throughout the life of the colony. The development of larval buds in this ascidian is not delayed until after dedifferentiation of the oozooid, as is the case in the other Holozoinae. The blastozooids function simultaneously with the oozooid. They do not, however, become sexually mature, being presumably of sub-maximal size for the species. The newly severed bud differs from that of other Holozoinae in having an extensive epicardial tube and a thick mesenchymal layer of densely granulated cells. The epicardium of the blastozooid is formed from the posterior end of the original epicardial tube. It remains single. The neural tube arises from the left peribranchial sac. H. fasmeriana forms a close link between the sub-family Holozoinae and the sub-family Polyclininae. It resembles the Holozoinae in form of gut, position and mode of origin of the brood pouch, and position of the cardio-pericardium. It shares with the Polyclininae the post-abdominal position of the gonads as well as the structure and organogenesis of the buds.

Labouring lives: the making of home eldercare assistants in Italy

Modern Italy ◽  
2011 ◽  
Vol 16 (3) ◽  
pp. 345-361 ◽  
Author(s):  
Francesca Degiuli
Keyword(s):  
Welfare State ◽  
Family Caregivers ◽  
Work Experience ◽  
The Other ◽  
Migrant Women ◽  
Extended Care ◽  
The Family ◽  
Double Function ◽  
The World ◽  
Different Levels

This paper explores how im/migrant women coming to Italy from all corners of the world and from very different backgrounds in terms of class, education and work experience are transformed into home eldercare assistants. The paper explores how these workers are created through discourses and every day practices enforced at different levels: from the state to the employers, from the mediators to the workers themselves. The creation of these workers has a double function: one is to fill the needs of a welfare state that otherwise would have to radically transform itself in order to provide effective services to the elders and, the other, is to alleviate the pressures of those of the family caregivers, mostly women, who otherwise would collapse under the burden of extended care.

Geographical bias constrains global knowledge of phenological change

2019 ◽  
Vol 25 (4) ◽  
pp. 345
Author(s):  
Nathalie Butt
Keyword(s):  
Climate Change ◽  
Life History ◽  
Egg Laying ◽  
The Other ◽  
Species Assemblages ◽  
Ecological Knowledge ◽  
Global Knowledge ◽  
Geographical Bias ◽  
And Migration ◽  
Northern And Southern Hemispheres

Climate change is already driving shifts in phenology, the timing of life-history events such as flowering, fruiting, egg-laying, birth, and migration, and this is set to increase. Although climate change is happening, and will continue to happen, globally, most of our ecological knowledge around its potential impacts on phenology is derived from temperate areas and ecosystems in the Northern Hemisphere, and information from the Southern Hemisphere is greatly lacking. This would not be a problem if biomes, ecosystems, species assemblages and species were the same in the Northern and Southern Hemispheres, but as they, in fact, differ across many factors and scales, understanding gained from one hemisphere is not necessarily applicable to the other.

Egg-laying and Hatching Postures and Habits of the American Lobster (Homarus americanus)

1937 ◽  
Vol 3 (4) ◽  
pp. 339-342 ◽  
Author(s):  
W. Templeman
Keyword(s):  
Homarus Americanus ◽  
Ventral Side ◽  
Egg Laying ◽  
American Lobster ◽  
Single Opening

During egg-laying Homarus americanus rests ventral side upwards on the tips of its chelae and on the first two abdominal segments. The abdomen is curved, forming a pocket with a single opening between the telson and the bases of the fifth pereiopods. While hatching its eggs the animal supports itself on the tips of the walking legs and extends the abdomen upward at an angle of 20° to 45°. The swimmerets are waved violently.

Zero and negative entrainment in turbulent shear flow

1971 ◽  
Vol 46 (2) ◽  
pp. 385-394 ◽  
Author(s):  
M. R. Head ◽  
P. Bradshaw
Keyword(s):  
Boundary Layer ◽  
Shear Flow ◽  
Outer Part ◽  
Radical Change ◽  
The Other ◽  
Turbulent Shear ◽  
Turbulence Structure ◽  
Turbulent Shear Flow ◽  
Flow Boundary ◽  
Other Hand

In certain accelerated flows the entrainment in the boundary layer, as normally defined, may be either zero or negative; on the other hand, there is no reason to suppose, on physical grounds, that the spread of mean or fluctuating vorticity should cease or become negative in such flows. This paradox is resolved in the present paper. It is also shown that in the equilibrium turbulent sink-flow boundary layer, where the entrainment as normally defined is zero, the reduced advection along streamlines in the outer part of the layer comes about mainly through increased dissipation: there is no reason to assume any radical change in the turbulence structure.

UPTAKE OF [3H]PROGESTERONE BY THE ANTERIOR LOBE OF PITUITARY AND SOME OTHER TISSUES OF THE HEN DURING AN OVULATORY CYCLE

1976 ◽  
Vol 82 (1) ◽  
pp. 47-51 ◽  
Author(s):  
Katuhide Tanaka ◽  
Michiharu Kamiyoshi ◽  
Mitsuo Kawashima
Keyword(s):  
Median Eminence ◽  
Pectoral Muscle ◽  
Anterior Lobe ◽  
Egg Laying ◽  
The Other ◽  
White Leghorn ◽  
Ovulatory Cycle ◽  
Laying Sequence

ABSTRACT [1,2-3H]progesterone was injected intravenously into White Leghorn hens at various times during the period between ovulations of the initial ovum and the second ovum (C2) of an egg-laying sequence, and the uptake of radioactivity was determined in tissues of the anterior lobe of pituitary, median eminence, telencephalon, liver, adrenal, magnum and pectoral muscle. The uptake by the anterior lobe of the pituitary changed during the ovulatory cycle showing a peak 8 h before C2 ovulation. Similar changes were also observed in the median eminence and in the magnum, but not in the other tissues examined.

The parasitic crustaceans of fishes from the Brazilian Amazon. 11. Vaigamidae fam. nov. (Copepoda: Poecilostomatoida) with males and females of Vaigamus retrobarbatus gen. et sp. nov. and V. spinicephalus sp. nov. from plankton

1984 ◽  
Vol 62 (4) ◽  
pp. 716-729 ◽  
Author(s):  
Vernon E. Thatcher ◽  
Barbara A. Robertson
Keyword(s):  
New Genus ◽  
Narrow Band ◽  
Antennal Segment ◽  
Brazilian Amazon ◽  
Thoracic Segment ◽  
The Other ◽  
The Third ◽  
Genital Segment ◽  
Pigment Distribution ◽  
Males And Females

Vaigamus retrobarbatus gen. et sp. nov. and V. spinicephalus sp. nov. (Copepoda: Poecilostomatoida) are described. The specimens were obtained by examining plankton samples from floodplain lakes of the Amazon River Basin in Brazil. The new genus is distinguished from all other genera and families in the suborder by the presence of retrostylets projecting laterally from the first thoracic segment and a long tapering rostral spine between the bases of the antennae. Vaigamidae fam. nov. is proposed for these forms. The two new species of the new genus are distinguished on the basis of the following characters. Size: retrobarbatus is larger than spinicephalus. Cephalothorax: that of spinicephalus is more ovoid. Pigment distribution: retrobarbatus had a broad transverse band of color on the cephalothorax while spinicephalus has a narrow band on the fourth thoracic segment. Rostral spine: spinicephalus has a spine with a subbasal swelling while that of the other species is smoothly tapering. Genital segment: that of retrobarbatus is more hexagonal. Antennal claw: in retrobarbatus the claw is longer than the third antennal segment while in the other species it is shorter. Leg 4: retrobarbatus has one fewer segment in each ramus than has the other species. Leg 6: that of retrobarbatus is longer.

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