نتایج جستجو برای: headed sperm cells

تعداد نتایج: 1418975  

Journal: :Plant physiology 2005
Michele L Engel Rachel Holmes-Davis Sheila McCormick

Previously, in an effort to better understand the male contribution to fertilization, we completed a maize (Zea mays) sperm expressed sequence tag project. Here, we used this resource to identify promoters that would direct gene expression in sperm cells. We used reverse transcription-polymerase chain reaction to identify probable sperm-specific transcripts in maize and then identified their be...

2015
Maximiliano Tourmente Eduardo R. S. Roldan Joël R Drevet

Mass-specific metabolic rate, the rate at which organisms consume energy per gram of body weight, is negatively associated with body size in metazoans. As a consequence, small species have higher cellular metabolic rates and are able to process resources at a faster rate than large species. Since mass-specific metabolic rate has been shown to constrain evolution of sperm traits, and most of the...

Kashefi S Mohammadi Roshandeh A Mortazavi M Salehi I Sohrabi M,

Background: Obesity and increased body mass index (BMI) affect the reproductive parameters in men such as poor semen quality, decreased sperm concentration, decreased normal-motile sperm cells and increased DNA fragmentation index. Lipid peroxidation contributes to the damage of the sperm plasma membrane. The Curcuma Longa is a resource of antioxidants, hence in this study also was evaluated th...

Journal: :Epj Web of Conferences 2022

A new, simple digital holography-based polarization microscope for quantitative birefringence imaging of biological cells is presented. As a proof concept, two different class have been characterized by sensitive holographic (PSDHI). These cases study reported are: differentiation leukaemia and identification reacted sperm cells. Although further experimentation necessary, the suggested approac...

2014
William E. Burnett Jürgen Heinze

In many insects, sperm cells are produced in bundles with their heads being held together by a glycoprotein matrix secreted by a cyst cell. Mature sperm cells in the seminal vesicles are usually free, but in sawflies and several other insects, such structures (spermatodesmata) remain intact and sperm cells may be ejaculated as bundles. Here we report the occurrence of spermatodesmata in mature ...

Journal: :Human reproduction 2002
A G Andersen S Ziebe N Jørgensen J H Petersen N E Skakkebaek A Nyboe Andersen

BACKGROUND In order to provide a reference for infertile men, we defined normal values of semen quality in a population of fertile men, using computer-assisted semen analysis (CASA) before and after sperm separation. Additionally, we investigated the relationship between semen quality and time to pregnancy (TTP). METHODS AND RESULTS Semen samples were obtained from 315 proven fertile men. The...

Journal: :Journal of andrology 1988
R J Aitken J S Clarkson

The mechanisms responsible for mediating the influence of sperm preparation protocols on human sperm function have been investigated. Techniques that involved the separation of motile spermatozoa prior to centrifugation were found to yield sperm suspensions of highest quality. If the spermatozoa were centrifuged prior to isolation of the motile cells, sperm function was impaired. The detrimenta...

Kashefi S Mohammadi Roshndeh A Mortazavi M, Salehi I Sohrabi M

Background: Obesity is a leading preventable cause of death worldwide, with increasing prevalence in adults and children. Some studies have shown that increased body mass index is related to poor semen quality, decreased sperm concentration, decreased normal-motile sperm cells and increased DNA fragmentation index. Lipid peroxidation contributes to the damage of the sperm plasma membrane. Cinna...

Journal: :Human reproduction 1998
Z M Kilani M A Shaban S D Ghunaim S S Keilani A I Dakkak

Intracytoplasmic sperm injection (ICSI) of round-headed spermatozoa into mature oocyte resulted in normal fertilization, embryo development and pregnancy in a 28 year old female. The husband had a long history of primary infertility. Three ICSI attempts were carried out and fertilization and embryo development occurred in all trials. However, only the third trial led to a pregnancy, which prove...

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