False-colour transmission electron micrograph (TEM) of an early stage of fertilisation,showing a human spermatozoon beginning to penetrate the corona radiata,the layers of follicular cells that surround the oocyte (the female sex cell - not visible). The cap over the head of each sperm,called the acrosome (light purple) contains enzymes which aid penetration of the egg. The dart-shaped head (dark purple) contains the 23 chromosomes of the male sex cell. Following the successful penetration of the egg by a single sperm,rapid chemical changes in the membrane surrounding the oocyte prevent entry of competing sperm. Magnification: x1000 at 35mm size | |
Lizenzart: | Lizenzpflichtig |
Credit: | Science Photo Library / Edelmann |
Bildgröße: | 5130 px × 3430 px |
Modell-Rechte: | nicht erforderlich |
Eigentums-Rechte: | nicht erforderlich |
Restrictions: |
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