One of the most significant, common signaling character of the event is that a prototype of professional chemotaxis receptors, formyl peptide receptor Thus, we agree with the earlier conclusions of Weber 32 that the elephant, like the dugong 33is a primary testicond mammal that shows no evidence of prior testicular descent. Sådana mutationer saknas dock hos äggcellerna. Kundrecensioner Har du läst boken? Fri frakt inom Sverige för privatpersoner. Nature London ; En spermie består av ett huvud, mellanstycke och svans.
Shaw for help with the figures, and David Paul and Bruce Abaloz for excellent photographic and histological assistance.
A Comparative Overview of Mammalian Fertilization
The youngest and oldest African elephant embryo and fetus used for this study. Evaluation and control of the fertilizing power of sperm. They surely are, being very diverse, very complex, containing organelles which do not exist in any other cell -such as acrosome or crystallized mitochondria- and being endowed with a very unique behaviour, that is to meet and recognize the ovum, pierce its protective envelopes and inject into its cytoplasm a most precious deposit, the haploid genome of the species. The whip-like tail flagellum of the sperm is studded with ion channels formed by proteins called CatSper. In this regard, I describe dynamic modifications and maturation events occurring in sperm-head components and compare the outcomes of these events with the outcomes of their failure.