Conception
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When does human life begin?
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We know that a woman's pregnancy results from a combination of several biological processes. Among these are:
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- The union of a male and female sex cell which produces a new single cell called zygote. This process is called fertilization. - The growth of the zygote by cell division, resulting in a hollow ball of cells called blastocyst. This process is called segmentation. - The attachment of the blastocyst to the lining of the uterus. This process is called implantation.
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If anything goes wrong with even one of these processes, no pregnancy can occur. Still, for certain scientific reasons many developmental biologists prefer to speak of a conception as soon as the process of fertilization is completed. On the other hand, some reproductive physiologists believe for their own scientific reasons that a new life begins with the process of implantation. For them, no conception occurs unless the fertilization leads to pregnancy.
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