Zona pellucida
Zona pellucida
Extracellular space
Oocyte plasma membrane
Sperm
Sperm
Granulosa cells
of corona radiata
Extracellular
space
Sperm, delivered to the vagina and
capacitated in the female reproductive
tract, stream toward a secondary
oocyte.
Figure 28.2
Sperm use acrosomal enzymes and receptors to
approach, bind, and enter the oocyte. The cortical reaction
prevents further sperm entry, ensuring that only two copies
of each chromosome are present in the fertilized ovum.
1
Approach.
Aided by enzymes
on its surface, a sperm cell
weaves its way past granulosa
cells of the corona radiata.
Polar body
Oocyte nucleus
arrested in meiotic
metaphase II
FOCUS
Sperm Penetration and the Cortical Reaction
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