Search results for "sperma"
showing 10 items of 296 documents
A note on the jelly-coat-sperm interaction in sea-urchin.
1952
Es werden Experimente beschrieben, die gegen eine enzymatische Spaltung der Gallerthulle des Seeigeleis durch Spermatozoen sprechen.
Gigaspermum mouretii Corb. (Gigaspermaceae, Musci), a new species from Italy
1998
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Nucleoside uptake in male germ cells of the polychaeteNereis virens
1997
Summary Uptake of inosine and guanosine was measured in male germ ceils of the polychaete Nereis virens at different stages of development. In spermatogonia I (spg I) and spermatid stages, total inosine uptake at 12°C and ambient concentrations of 100 μmol/1 was relatively low (10–50 nmol·ml of packed cell volume pcv−l·h−1). A rapid increase (150–300 nmol·ml of pcv-1·h−1) was found during transition from spg I to spg II with a subsequent decline to low values (10–30 nmol·ml of pcv−1·h−1) in spermatocyte and spermatid stages. This transient increase may be related to the proliferative activity of spg I stages leading to spg II stages, which increases the demand of purine precursors for nucle…
Effect of host plant quality on male sexual performances and consequences on female reproductive output in a phytophagous moth
2016
The abundance of phytophagous insects is determined by numerous interacting biotic and abiotic factors. In capital-breeding phytophagous insects, larval host plant quality is a key determinant of the adult phenotype and the performance of both males and females. Curiously, if the effect of host plant quality on female reproductive success is well-established, little effort has been conducted to determine this effect on male reproductive success. Moreover, in Lepidoptera, males transfer to females a spermatophore containing sperm and accessory gland products rich in nutrients that could be reinvested into female reproduction. The aim of this thesis was to evaluate how male larval nutrition o…
Male reproductive senescence as a potential source of sexual conflict in a beetle
2011
The link between senescence and reproductive success is a contentious yet crucial issue to our understanding of mate choice, sexual conflict, and the evolution of ageing. By imposing direct (i.e., male fertility) or indirect (i.e., zygote viability) reproductive costs to females, male senescence may lead to sexual conflict at different levels. For example, ageing may affect male ability to deliver sperm, thus setting the scene for sexual conflict over mating, and/or may affect the quality of individual sperm cells, generating the potential for sexual conflict over fertilizing strategies. We addressed these issues by studying the mating behavior, reproductive fitness, and fertilization patte…
Alpha-adrenergic drugs in retrograde ejaculation.
1974
6 men with complete or partial loss of ejaculation as a result of retroperitoneal lymphadenectomy (performed because of testicular tumor) were treated with an intravenous injection of 60 mg synephrine. Synephrine stimulates adrenergic alpha-receptors. Only 1 man with sustained retrograde ejaculation improved following treatment showing antegrade ejaculation. This temporary restoration of fertility was thought to be due to an increase in bladder neck tone and prevention of backflow of semen into the bladder as a result of stimulation of adrenergic alpha-receptors.
Forecasting the onset of an allergic risk to poaceae in Nancy and Strasbourg (France) with different methods
2008
International audience; Pollen of Poaceae is among the most allergenic pollen in Europe with pollen of birch. It is therefore useful to elaborate models to help pollen allergy sufferers. The objective of this study was to construct forecast models that could predict the first day characterized by a certain level of allergic risk called here the Starting Date of the Allergic Risk . Models result from four forecast methods (three summing and one multiple regression analysis) used in the literature. They were applied on Nancy and Strasbourg from 1988 to 2005 and were tested on 2006. Mean Absolute Error and Actual forecast abili ty test are the parameters used to choose best models, assess and …