نتایج جستجو برای: sperm coating

تعداد نتایج: 73758  

2013
Nichola J. Coleman

A study has been carried out to determine the effect of coating two commercial glass-ionomer cements in either petroleum jelly or wax. After coating, specimens were stored in water for 24 or 168 hours, then the coating removed and the surface examined. Coating in wax was found to increase the surface hardness significantly compared with the uncoated control, whereas coating the specimens in pet...

2015

The purpose of this work was to develop a practical scale-up model for a solvent-based pan-coating process. scale up of adsorption column Practical scale-up rules to determine. ABSTRACT: Although significant progress had been made in developing general scale-up rules for an aqueous pan-coating process, there. Practical scale-up rules to determine the key parameters pan load, pan speed, spray ra...

Journal: :Current Biology 2012
Teri J. Orr Marlene Zuk

What is sperm storage? Sperm storage is most commonly defined as the maintenance of sperm inside a female’s reproductive tract for an extended period of time. Because the fate of sperm post-copulation is important for understanding sexual selection, sperm storage is a particularly interesting characteristic that may have drastic impacts on the operation of post-copulatory sexual selection. Sper...

2017
Li Wang Lin Zhang Xiao-Hui Song Hao-Bo Zhang Cheng-Yan Xu Zi-Jiang Chen

Semen from 5210 sperm bank donors was analyzed and trends in semen quality were evaluated at Shandong Human Sperm Bank between 2008 and 2014. After 2-7 days of abstinence, semen samples were collected. Measurements of semen volume, sperm concentration, sperm forward motility, and total sperm count were performed. There were significant declining trends in semen volume, sperm concentration, sper...

Journal: :The International journal of developmental biology 2008
Susan S Suarez

The oviduct plays a vital role in ensuring successful fertilization and normal early embryonic development. The male inseminates many thousands or even millions of sperm, but this alone does not ensure that fertilization will be successful. The female tract, particularly the oviduct, provides filters that select for normal vigorously motile sperm. In conjunction with molecules in the seminal pl...

Journal: :Evolution; international journal of organic evolution 2005
Paul D Williams Troy Day Erin Cameron

The prevailing viewpoint in the study of sperm competition is that male sperm-allocation strategies evolve in response to the degree of sperm competition an ejaculate can expect to experience within a given mating. If males cannot assess the degree of sperm competition their ejaculate will face and/or they are unable to facultatively adjust sperm investment in response to perceived levels of co...

Journal: :The Journal of Cell Biology 1980
D E Chandler J Heuser

Eggs of the sea urchin Strongylocentrotus purpuratus were quick-frozen, freeze fractured, and deep-etched to reveal the detailed structure of the vitelline layer (VL), an extracellular coat. The VL consisted of a network of fibers lying in sheet raised 20 nm off the plasma membrane and connected to it by a series of short processes. Sperm attached to the fibers of this sheet and upon fertilizat...

Journal: :Biology letters 2010
John L Fitzpatrick Francisco Garcia-Gonzalez Jonathan P Evans

Selection imposed through sperm competition is commonly thought to promote the evolution of longer sperm, since sperm length is assumed to be positively associated with sperm swimming velocity. Yet, the basis for this assumption remains controversial, and there is surprisingly little intraspecific evidence demonstrating such a link between sperm form and function. Here, we show that sperm lengt...

2017
Nicola Hemmings Tim Birkhead

When females mate promiscuously, female sperm storage provides scope to bias the fertilization success towards particular males via the non-random acceptance and utilization of sperm. The difficulties observing post-copulatory processes within the female reproductive tract mean that the mechanisms underlying cryptic female choice remain poorly understood. Here, we use zebra finches Taeniopygia ...

2014
Juan Ye Xueting Cai Peng Cao

Tongue diagnosis in traditional Chinese medicine (TCM) assesses the health by investigation of tongue coating. The science and technology of tongue coating analysis have become a significant issue for modernization of TCM. The relationship between microecology of tongue coating and TCM was relevant to the syndrome differentiation in TCM, such as the cold/hot syndrome may exhibit different speci...

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