نتایج جستجو برای: bull sperm

تعداد نتایج: 43630  

2014
Vasily Kantsler Jörn Dunkel Martyn Blayney Raymond E Goldstein

A major puzzle in biology is how mammalian sperm maintain the correct swimming direction during various phases of the sexual reproduction process. Whilst chemotaxis may dominate near the ovum, it is unclear which cues guide spermatozoa on their long journey towards the egg. Hypothesized mechanisms range from peristaltic pumping to temperature sensing and response to fluid flow variations (rheot...

2008
D. W. Erikson A. L. Way R. P. Bertolla D. A. Chapman G. J. Killian

Sperm must undergo a process termed capacitation in the female reproductive tract before they are capable of fertilization. Previous studies strongly suggest that capacitation of sperm occurs in the oviduct. The secreted extracellular matrix phosphoprotein osteopontin (OPN) has been positively correlated to fertility in Holstein bull seminal plasma and identified in the bovine oviduct, where we...

2013
José O. Carvalho Luciano P. Silva Roberto Sartori Margot A. N. Dode

Sperm dimensions and the question of whether X and Y chromosome-bearing sperm differ in size or shape has been of great interest, especially for the development of alternative methods to sort or classify sperm cells. The aim of the present study was to evaluate possible differences in the shape and size of the sperm head between X and Y chromosome-bearing sperm by atomic force microscopy (AFM)....

Journal: :Biotechnology in Animal Husbandry 2005

Background sperm selection is generally used to describe methods for separation of spermatozoa for in-vitro-assisted reproduction. Few studies reported relation in vivo fertility and semen parameters after selection of fertile spermatozoa; hence, our research attempt to assess different semen parameters after post-thaw (PT) or after selecting sperm sample (SSp), using density gradient separatio...

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