False-colour transmission electron micrograph (TEM) of an egg (ovum) during fertilisation,showing a human spermatozoon penetrating the zona pellucida,the thick membrane that surrounds the oocyte,the female sex cell. The dart-shaped head (dark purple) contains the 23 chromosomes of the male sex cell. Following the successful penetration of the oocyte by a single sperm,rapid chemical changes in the membrane surrounding the oocyte cause it to thicken and prevent entry of competing sperm. Magnification: x1000 at 35mm size | |
Lizenzart: | Lizenzpflichtig |
Credit: | Science Photo Library / Edelmann |
Bildgröße: | 5144 px × 3443 px |
Modell-Rechte: | nicht erforderlich |
Eigentums-Rechte: | nicht erforderlich |
Restrictions: |
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